Inhibitory activity of garlic (Allium sativum) extract on multidrug-resistant Streptococcus mutans.

J Indian Soc Pedod Prev Dent. 2007 Oct-Dec;25(4):164-8

Authors: Fani MM, Kohanteb J, Dayaghi M

Garlic ( Allium sativum ) extract has been known to have inhibitory activity on various pathogenic bacteria, viruses and fungi. The objective of present investigation was to study in vitro inhibitory activity of garlic extract on multidrug-resistant (MDR) strains of Streptococcus mutans isolated from human carious teeth. Filter sterilized aqueous extract of garlic was prepared and used in the present study. For isolation of S. mutans , extracted human carious teeth were cultured in Todd-Hewit broth and Mitis-Salivarius-Bacitracin agar. S. mutans was characterized by colony morphology, biochemical tests and other conventional bacteriological procedures. Disk sensitivity tests and broth dilution methods were used to determine antibiotic sensitivity profile and inhibitory activity of garlic extract on S. mutans isolated from carious teeth. Of 105 carious teeth tested, 92 (87.6%) isolates of S. mutans were recovered, among which 28 (30.4%) were MDR since they were resistant to four or more antibiotics. The highest rate of resistance was observed for tetracycline (30.4%) and least resistance (0%) to teichoplanin and vancomycin while 22.8% and 23.9% of the isolates were resistant to penicillin and amoxicillin, respectively. Chlorhexidine minimum inhibitory concentration (MIC) for MDR and non-MDR S. mutans varied from 2 to 16 microg ml-1 and from 0.25 to 1 microg ml-1 , respectively ( P S. mutans were sensitive to garlic extract with the MIC ranging from 4 to 32 mg ml-1 . Considering in vitro data obtained in the present study, mouthwashes or toothpaste containing optimum concentration of garlic extract could be used for prevention of dental caries.

PMID: 18007101 [PubMed - in process]

Antimicrobial analysis of different root canal filling pastes used in pediatric dentistry by two experimental methods.

Braz Dent J. 2006;17(4):317-22

Authors: Amorim Lde F, Toledo OA, Estrela CR, Decurcio Dde A, Estrela C

The objective of this study was to compare, by two experimental methods, the antimicrobial efficacy of different root canal filling pastes used in pediatric dentistry. The tested materials were: Guedes-Pinto paste (GPP), zinc oxide-eugenol paste (OZEP), calcium hydroxide paste (CHP), chloramphenicol + tetracycline + zinc oxide and eugenol paste (CTZP) and Vitapex. Fiven microbial strains (S. aureus, E. faecalis, P. aeruginosa, B. subtilis and C. albicans) obtained from the American Type Culture Collection were inoculated in Brain Heart Infusion (BHI) and incubated at 37 degrees C for 24 h. For the direct exposure test (DET), 72 paper points were contaminated with the standard microbial suspensions and exposed to the root canal filling pastes for 1, 24, 48 and 72 h. The points were immersed in Letheen Broth (LB), followed by incubation at 37 degrees C for 48 h. An inoculum of 0.1 mL obtained from LB was then transferred to 7 mL of BHI, under identical incubations conditions and the microbial growth was evaluated. The pastes showed activity between 1 and 24 h, depending on the material. For the agar diffusion test (ADT), 30 Petri plates with 20 mL of BHI agar were inoculated with 0.1 mL of the microbial suspension, using sterile swabs that were spread on the medium. Three cavities were made in each agar plate (total = 90) and completely filled with one of the filling root canal pastes. The plates were pre-incubated for 1 h at room temperature and then incubated at 37 degrees C for 24 to 48 h. The inhibition zone around each well was recorded in mm. The complete antimicrobial effect in the direct exposure test was observed after 24 h on all microbial indicators. All root canal filling materials induced the formation of inhibition zones, except for Vitapex (range, 6.0-39.0 mm).

PMID: 17262146 [PubMed - indexed for MEDLINE]

The attachment of V79 and human periodontal ligament fibroblasts on periodontally involved root surfaces following treatment with EDTA, citric acid, or tetracycline HCL: an SEM in vitro study.

J Contemp Dent Pract. 2006 Feb 15;7(1):44-59

Authors: Chandra RV, Jagetia GC, Bhat KM

OBJECTIVE: The present in vitro study has been designed to establish and compare the effects of citric acid, EDTA, and tetracycline HCl on human periodontally diseased roots on the structure, attachment, and orientation of V79 (primary Chinese hamster lung fibroblasts) cells and human periodontal ligament fibroblasts (HPDL). MATERIALS AND METHODS: Commercially available V79 cells and HPDL derived from healthy human third molars were used in this study. These fibroblasts were left in solution for seven days in order to attain confluence. Forty single-rooted teeth were obtained from patients diagnosed with periodontitis. The crown part was removed under constant irrigation and the root was split vertically into two equal halves, thus, yielding 80 specimens. Following scaling and root planing, the specimens were washed with phosphate buffered saline (PBS) and kept in 50 microg/ml gentamycin sulphate solution for 24 hours. The root pieces were then treated as follows: citric acid at pH 1, 24% EDTA, or with a 10% solution of tetracycline HCl and were then placed in V79 fibroblast cultures and HPDL cultures. The specimens were harvested after four weeks and were fixed in 2.5% glutaraldehyde in PBS before preparation for scanning electron microscopy (SEM). RESULTS: The behavior of V79 cells was similar to that of human periodontal ligament cells on root conditioned surfaces. V79 and HPDL showed a healthy morphology on root surfaces treated with citric acid and EDTA and a relatively unhealthy appearance on root surfaces treated with tetracycline HCl and distilled water (control group). CONCLUSION: The results suggest the use of citric acid and EDTA as root conditioning agents favorably affects the migration, attachment, and morphology of fibroblasts on human root surfaces, which may play a significant role in periodontal healing and regeneration.

PMID: 16491147 [PubMed - indexed for MEDLINE]

Antibiotic susceptibility of the bacteria causing odontogenic infections.

Med Oral Patol Oral Cir Bucal. 2006 Jan;11(1):E70-5

Authors: Brescó-Salinas M, Costa-Riu N, Berini-Aytés L, Gay-Escoda C

AIMS: An evaluation is made of bacterial species and susceptibility to various antibiotics used in application to odontogenic infections of periapical location and in pericoronitis of the lower third molar, with the aim of optimizing the antibiotherapy of such infections and thus preventing unnecessary side effects and over-treatment. MATERIAL AND METHODS: Sixty-four patients with odontogenic infection were selected on the basis of a series of inclusion and exclusion criteria. Samples were collected from lesions under maximally aseptic conditions, avoiding oral saprophytic contamination. The samples were cultured and incubated under aerobic and anaerobic conditions, followed by bacteriological identification and antibiotic susceptibility testing. RESULTS: A total of 184 bacterial strains were isolated and identified, comprising grampositive facultative anaerobes (68%), gramnegative strict anaerobes (30%) and grampositive facultative anaerobes (2%). Regardless of the origin of the odontogenic infection, the causal bacteria yielded the best results in terms of increased sensitivity and lesser resistance with amoxicillin / clavulanate and amoxicillin, respectively (p<0.05). DISCUSSION: There are increasingly numerous reports in the literature of growing bacterial resistance to antibiotics in infectious processes affecting non-buccodental territories. This same tendency has not been observed in relation to oral infections, though important resistance has been documented for certain concrete antibiotics. According to our results, the common-use antibiotics with the greatest sensitivity and lowest resistance were shown to be amoxicillin/clavulanate followed by amoxicillin alone.

PMID: 16388299 [PubMed - indexed for MEDLINE]

Prevalence of oral diseases/conditions in Uganda.

Afr Health Sci. 2005 Sep;5(3):227-33

Authors: Muwazi LM, Rwenyonyi CM, Tirwomwe FJ, Ssali C, Kasangaki A, Nkamba ME, Ekwaru P

Objectives: The aim was to report the prevalence of oral diseases/conditions among a Ugandan population. Methods: Subjects aged 12 (n=696) and 35-44 years (n=396) were chosen from randomly selected urban and peri-urban areas of Arua, Mbale, Kampala and Mbarara districts. They were clinically examined by 4 trained and calibrated dentists for oral diseases/conditions using criteria described by World Health Organisation. Results: Dental caries (DMFT >/=1) was recorded in 40% and 62.5% of the children and adults, respectively. The overall mean DMFT score was 0.9 for children and 3.4 for adults. Caries was significantly more severe in females as compared to males in children (p<0.05), whereas in adults, there was no significant gender difference. Kampala had a significantly higher mean DMFT score compared to other districts in all age groups (p>0.05). Culculus deposits were generally, more prevalent in adults as compare to children except in Mbarara district. Gum bleeding was also significantly more prevalent among children as compared to adults (p<0.05). Significantly higher prevalence of gum bleeding in both children and adults was recorded in Arua district as compared to other areas (p<0.05). Each of the age groups had a prevalence of malocclusion of 61%. However, the severity of malocclusion varied between age groups and districts. The prevalence of dental fluorosis was 3% and 4% for children and adults, respectively. All subjects in Arua district were fluorosis-free. Tetracycline enamel staining was less than 1% in both age groups. Enamel attrition was more prevalent in adults as compared to children: 19% versus 1%. Conclusion: The prevalence of oral diseases/conditions was generally low among the study population. Caries experience was significantly higher in the Kampala (urban) district as compared to rural districts in all age groups; the D - component being the major contributor.

PMID: 16245993 [PubMed - in process]

Drug-induced disorders of teeth.

J Dent Res. 2005 Jul;84(7):596-602

Authors: Tredwin CJ, Scully C, Bagan-Sebastian JV

It is essential that every health care professional who is involved with the prescription or recommendation of drugs be fully aware of any resultant disorders that may arise as a side-effect. A range of drugs can affect the teeth. In this review article, drugs that have the potential to induce changes in teeth have been classified as those leading to tooth discoloration (intrinsic and extrinsic), physical damage to tooth structure (enamel, dentin, and cementum), and alteration in tooth sensitivity.

PMID: 15972585 [PubMed - indexed for MEDLINE]

Antimicrobial susceptibility testing of Actinomyces species with 12 antimicrobial agents.

J Antimicrob Chemother. 2005 Aug;56(2):407-9

Authors: Smith AJ, Hall V, Thakker B, Gemmell CG

OBJECTIVE: This study was conducted to assess the susceptibility of human clinical isolates of Actinomyces species to 12 antimicrobial agents. METHODS: Human clinical isolates of Actinomyces spp. were collected from stored collections held at the Microbiology Department, Edinburgh University, Anaerobe Reference Laboratory, Cardiff, Glasgow Dental Hospital and Glasgow Royal Infirmary. Each isolate was identified by restriction analysis of amplified 16S ribosomal DNA. MICs of 12 antibiotics comprising benzyl penicillin, amoxicillin, ceftriaxone, linezolid, tetracycline, deoxycycline, clindamycin, erythromycin, clarithromycin, ciprofloxacin, meropenem and piperacillin/tazobactam for 87 strains of Actinomyces species were obtained by Etest methodology. RESULTS: The Actinomyces species identified for this study comprised: Actinomyces israelii, Actinomyces gerencseriae, Actinomyces turicensis, Actinomyces funkei, Actinomyces graevenitzii and Actinomyces europaeus. All isolates were susceptible to penicillin and amoxicillin. All but one strain of A. turicensis was susceptible to linezolid. A number of A. europaeus and A. graevenitzii isolates were resistant to ceftriaxone and piperacillin/tazobactam. A number of isolates of A. turicensis and A. europaeus also demonstrated resistance to erythromycin. All Actinomyces species tested appeared resistant to ciprofloxacin. CONCLUSIONS: Actinomyces species appear to be susceptible to a wide range of beta-lactam agents and these, when combined with beta-lactamase inhibitors, should be regarded as agents of first choice. Ciprofloxacin performed poorly. Tetracyclines also demonstrated poor performance. This is the first study of antimicrobial susceptibilities for a number of accurately identified clinical isolates of Actinomyces spp. There are a number of species differences in susceptibility profiles to the antimicrobials tested, suggesting that accurate identification and speciation may have an impact on clinical outcome.

PMID: 15972310 [PubMed - indexed for MEDLINE]

Staphylococcus aureus ampicillin-resistant from the odontological clinic environment.

Rev Inst Med Trop Sao Paulo. 2005 Jan-Feb;47(1):19-24

Authors: Bernardo WL, Boriollo MF, Gon&#xE7;alves RB, Höfling JF

The aim of this research was to evaluate the prevalence of Staphylococcus spp. and S. aureus in the odontological clinic environment (air), their production of beta-lactamase and antibacterial susceptibility to the major antibiotics utilized in medical particle. During 12 months of samples collect were isolated 9775 CFU by MSA medium suggesting a high amount of Staphylococcus spp. in the clinic environment which can appear through aerosols. A total of 3149 colonies (32.2%) were suggestive of pathogenic staphylococci. Gram coloration, catalase test, colony-mallow growing on chromogenic medium, and coagulase test confirmed the identity of 44 (0.45%) S. aureus isolates. Of these, 35 isolates (79.5%) showed production of beta-lactamase by Cefinase discs and resistance to ampicillin, erythromycin (7 isolates) and tetracycline (1 isolate) suggesting the existence of multiresistant isolates. The evaluation of the oxacillin MIC by Etest assays showed susceptibility patterns suggesting the inexistence of the mecA gene in chromosomal DNA. These results point out to the need of a larger knowledge on the contamination means and propagation of this microorganism into the odontological clinic.

PMID: 15729470 [PubMed - indexed for MEDLINE]

Daptomycin tested against 915 bloodstream isolates of viridans group streptococci (eight species) and Streptococcus bovis.

J Antimicrob Chemother. 2005 Apr;55(4):574-8

Authors: Streit JM, Steenbergen JN, Thorne GM, Alder J, Jones RN

OBJECTIVES: To evaluate the activity of daptomycin tested against numerous species of viridans group streptococci and Streptococcus bovis, which are associated with wound infections, sepsis, cellulitis, endocarditis, abscesses and dental caries. The incidence of penicillin-resistant (non-susceptible) and MLS(B)-resistant strains among viridans group streptococci often varies by species. METHODS: The activity of daptomycin was compared with seven other antimicrobial classes using reference broth microdilution and disc diffusion methods tested against 915 bacteraemic isolates of streptococci (815 viridans group strains; 100 S. bovis). RESULTS: Among all species of viridans group streptococci and S. bovis, 99.9% of isolates were susceptible to daptomycin (MIC values, < or = 0.016-2 mg/L). In contrast, penicillin, erythromycin and tetracycline susceptibility varied widely between species. Erythromycin susceptibility was in the range 48.6-88.7%, penicillin susceptibility in the range 65.5-98.1% and tetracycline in the range 35.0-93.9%. The inter-method agreement between daptomycin and linezolid resistance (comparison agent) disc diffusion and broth microdilution test results was high, each showing near complete susceptibility (99.9%). CONCLUSIONS: Daptomycin is an active antimicrobial agent that has a usable potency against eight species of viridans group streptococci, as well as S. bovis, with all MIC values at < or =2 mg/L.

PMID: 15722390 [PubMed - indexed for MEDLINE]

Periimplantitis.

Med Oral Patol Oral Cir Bucal. 2004;9 Suppl:69-74; 63-9

Authors: S&#xE1;nchez-Gárces MA, Gay-Escoda C

Orodental rehabilitation through the use of implants offers very high success rates. In this paper, we describe some of the complications involved with this technique, such as periimplant disease and, within this category, periimplantitis, an inflammatory reaction in which there is a loss of the bony support of the implant accompanied by inflammation. The aetiology of the disease is conditioned by the status of the tissue surrounding the implant, implant design, degree of roughness, the poor alignment of implant components, external morphology and excessive mechanical load. The microorganisms most commonly associated with implant failure are spirochetes and mobile forms of Gram-negative anaerobes, unless the origin is the result of simple mechanical overload. Diagnosis is based on changes of colour in the gum, bleeding and probing depth of periimplant pockets, suppuration, x-ray and gradual loss of bone height around the tooth. Treatment will differ depending upon whether it is a case of mucositis or periimplantitis. Therapeutic objectives focus on correcting technical defects by means of surgery and decontamination techniques (abrasion with carbon particles, citric acid solution, topical tetracycline application and laser surgery). This study also presents a microbiological study of periimplantitis conducted by the Barcelona School of Dentistry that determined that the antibiotic therapy proven to be most efficacious in the antibiogram was the association of amoxycillin and clavulanic acid.

PMID: 15580138 [PubMed - indexed for MEDLINE]

Antimicrobial susceptibility of bifidobacteria.

J Antimicrob Chemother. 2005 Jan;55(1):38-44

Authors: Moubareck C, Gavini F, Vaugien L, Butel MJ, Doucet-Populaire F

OBJECTIVES: The aim of our study was to analyse the antibiotic susceptibility of various strains of Bifidobacterium spp. to a wide range of antimicrobial agents. METHODS: Fifty strains belonging to eight species of bifidobacteria, isolated from humans, animals or probiotic products, were tested for susceptibility to 30 antibiotics by disc diffusion on Brucella agar supplemented with 5% laked sheep blood and vitamin K1 (1 mg/L). MICs of nine anti-anaerobe agents, including three new molecules (telithromycin, linezolid and gatifloxacin), were determined using the reference agar-dilution method. RESULTS: All strains of bifidobacteria, whatever the species, were sensitive to penicillins: penicillin G, amoxicillin (MIC(50) 0.06 mg/L), piperacillin, ticarcillin, imipenem and usually anti-Gram-positive antibiotics (macrolides, clindamycin, pristinamycin, vancomycin and teicoplanin). Susceptibility to cefalothin and cefotetan was variable. Most isolates (70%) were resistant to fusidic acid. As expected, high resistance rates were observed for aminoglycosides. Metronidazole, an agent known for its anti-anaerobe activity, was ineffective against 38% of the strains. The newly commercialized molecules, telithromycin, linezolid and gatifloxacin, were active with MIC(50)S of 1 mg/L. The only variation in susceptibility observed among the different species concerned Bifidobacterium breve, which appeared to be generally more resistant. Potentially acquired resistance was only observed against tetracycline and minocycline, in 14% of the strains. CONCLUSIONS: With regard to a general concern about the safety of probiotics, such as potential transferability of resistance determinants, bifidobacteria, with their low natural and acquired resistance to 30 antibiotics, appear risk-free.

PMID: 15574479 [PubMed - indexed for MEDLINE]

Effect of amoxicillin use on oral microbiota in young children.

Antimicrob Agents Chemother. 2004 Aug;48(8):2883-7

Authors: Ready D, Lancaster H, Qureshi F, Bedi R, Mullany P, Wilson M

Dental plaque samples from 40 children were screened for the presence of bacteria resistant to amoxicillin. Fifteen children had used amoxicillin and 25 had not used any antibiotic in the 3 months prior to sample collection. All (100%) of the children harbored amoxicillin-resistant oral bacteria. The median percentage of the total cultivable oral microbiota resistant to amoxicillin was 2.4% (range, 0.1 to 14.3%) in children without amoxicillin use and 10.9% (range, 0.8 to 97.3%) in children with amoxicillin use, with the latter value being significantly higher (P < 0.01). A total of 224 amoxicillin-resistant bacteria were isolated and comprised three main genera: Haemophilus spp., Streptococcus spp., and Veillonella spp. The biodiversity of the amoxicillin-resistant microbiota was similar among the isolates from children with and without previous antibiotic use. The amoxicillin MIC at which 90% of the isolates were inhibited for isolates from children who had used amoxicillin in the previous 3 months was higher (64 mg liter(-1)) than that obtained for the isolates from subjects who had not used antibiotics (16 mg liter(-1)). The majority of the amoxicillin-resistant isolates (65%) were also resistant to at least one of the three antibiotics tested (penicillin, erythromycin, and tetracycline), with resistance to penicillin (51% of isolates) being the most frequently encountered. However, significantly more (P < 0.05) of the amoxicillin-resistant isolates from subjects with previous amoxicillin use were also resistant to erythromycin. This study has demonstrated that a diverse collection of amoxicillin-resistant bacteria is present in the oral cavity and that the number, proportions, MICs, and resistance to erythromycin can significantly increase with amoxicillin use.

PMID: 15273096 [PubMed - indexed for MEDLINE]

Effectiveness of antimicrobial adjuncts to scaling and root-planing therapy for periodontitis.

Evid Rep Technol Assess (Summ). 2004 Jan;(88):1-4

Authors: Bonito AJ, Lohr KN, Lux L, Sutton S, Jackman A, Whitener L, Evensen C

PMID: 15164672 [PubMed - indexed for MEDLINE]

[Use of antimicrobial drugs in an urban population]

Rev Saude Publica. 2004 Apr;38(2):239-46

Authors: Berqu&#xF3; LS, Barros AJ, Lima RC, Bertoldi AD

OBJECTIVE: The emergence of multiresistant microorganisms has been a concerning matter worldwide in the last decades. Indiscriminate use of antibiotics has been associated to this phenomenon. The present study was designed to determine the pattern of antimicrobial drug use in an urban community. METHODS: A population-based cross-sectional study was carried out and 6,145 subjects of all ages living in the urban area of Pelotas, Brazil, were interviewed on the use of antimicrobial drugs in the 30 days previous to the interview. RESULTS: The overall prevalence of antimicrobial drug use was 8%. It was higher for children under 4 years of age (14%; p<0.001), women (9%; p=0.004) and divorced subjects (10%; p=0.02). The clinical conditions most frequently associated with antimicrobial drug use were respiratory tract infections (50%), urinary tract infections (16%), and dental infections (9%). Penicillins (41%), sulphas (17%), and tetracycline (8%) were the most commonly used drugs. CONCLUSIONS: Abuse of last generation antimicrobial drugs, a concern of many experts, was not confirmed in this study. Antimicrobial drug use could be further reduced as respiratory illnesses, most frequently associated with their use, are often viral and many patients will not benefit from antimicrobial therapy.

PMID: 15122380 [PubMed - indexed for MEDLINE]

Selection for high-level resistance by chronic triclosan exposure is not universal.

J Antimicrob Chemother. 2004 May;53(5):772-7

Authors: McBain AJ, Ledder RG, Sreenivasan P, Gilbert P

OBJECTIVES: To investigate the effect of triclosan exposure on the antimicrobial susceptibilities of numerically important dental bacteria. METHODS: A gradient plate technique was used to expose Fusobacterium nucleatum, Lactobacillus rhamnosus, Neisseria subflava, Porphyromonas gingivalis, Actinomyces naeslundii, Prevotella nigrescens, Streptococcus oralis, Streptococcus sanguis, Streptococcus mutans and Veillonella dispar repeatedly to escalating, sublethal concentrations of triclosan. Escherichia coli ATCC 8739 was included as an organism showing the triclosan resistance development trait. MIC values towards chlorhexidine, metronidazole and tetracycline were determined before and after biocide exposure. RESULTS: N. subflava, Pr. nigrescens Po. gingivalis and E. coli were highly susceptible to triclosan (MIC range 0.1-3.9 mg/L), whereas the lactobacillus and S. mutans were less susceptible (MIC range 15.6-20.8 mg/L). Triclosan exposure resulted in a highly significant ( approximately 400-fold) reduction in triclosan susceptibility (P < 0.01) for the positive control E. coli, although its MICs towards chlorhexidine, metronidazole and tetracycline were not significantly altered. Minor ( approximately two-fold) decreases in triclosan susceptibility (MIC) occurred for Pr. nigrescens and in S. sanguis and S. oralis (MBC). Mean changes in susceptibilities (MIC and MBC) of the oral species to chlorhexidine, metronidazole and tetracycline did not exceed two-fold, although chlorhexidine MBCs for S. sanguis were markedly, but transiently, increased. CONCLUSIONS: These data fail to demonstrate biologically significant drug resistance in triclosan-exposed bacteria and suggest that markedly decreased triclosan susceptibility, although confirmed for E. coli, is not a universal phenomenon. Other bacteria possibly possess more susceptible targets than FabI that are highly conserved, which may govern triclosan activity.

PMID: 15117935 [PubMed - indexed for MEDLINE]

Novel tetracycline resistance determinant from the oral metagenome.

Antimicrob Agents Chemother. 2003 Apr;47(4):1430-2

Authors: Diaz-Torres ML, McNab R, Spratt DA, Villedieu A, Hunt N, Wilson M, Mullany P

A major drawback of most studies on how bacteria become resistant to antibiotics is that they concentrate mainly on bacteria that can be cultivated in the laboratory. In the present study, we cloned part of the oral metagenome and isolated a novel tetracycline resistance gene, tet(37), which inactivates tetracycline.

PMID: 12654685 [PubMed - indexed for MEDLINE]

Prevalence of tetracycline resistance genes in oral bacteria.

Antimicrob Agents Chemother. 2003 Mar;47(3):878-82

Authors: Villedieu A, Diaz-Torres ML, Hunt N, McNab R, Spratt DA, Wilson M, Mullany P

Tetracycline is a broad-spectrum antibiotic used in humans, animals, and aquaculture; therefore, many bacteria from different ecosystems are exposed to this antibiotic. In order to determine the genetic basis for resistance to tetracycline in bacteria from the oral cavity, saliva and dental plaque samples were obtained from 20 healthy adults who had not taken antibiotics during the previous 3 months. The samples were screened for the presence of bacteria resistant to tetracycline, and the tetracycline resistance genes in these isolates were identified by multiplex PCR and DNA sequencing. Tetracycline-resistant bacteria constituted an average of 11% of the total cultivable oral microflora. A representative 105 tetracycline-resistant isolates from the 20 samples were investigated; most of the isolates carried tetracycline resistance genes encoding a ribosomal protection protein. The most common tet gene identified was tet(M), which was found in 79% of all the isolates. The second most common gene identified was tet(W), which was found in 21% of all the isolates, followed by tet(O) and tet(Q) (10.5 and 9.5% of the isolates, respectively) and then tet(S) (2.8% of the isolates). Tetracycline resistance genes encoding an efflux protein were detected in 4.8% of all the tetracycline-resistant isolates; 2.8% of the isolates had tet(L) and 1% carried tet(A) and tet(K) each. The results have shown that a variety of tetracycline resistance genes are present in the oral microflora of healthy adults. This is the first report of tet(W) in oral bacteria and the first report to show that tet(O), tet(Q), tet(A), and tet(S) can be found in some oral species.

PMID: 12604515 [PubMed - indexed for MEDLINE]

The effect of a 10% carbamide peroxide home bleaching system on the gingival health.

J Contemp Dent Pract. 2003 Feb 15;4(1):32-41

Authors: Almas K, Al-Harbi M, Al-Gunaim M

Esthetics plays an important role in dentistry today. Because of an increased emphasis on beauty and health, cosmetic dentistry has been the thrust to the forefront of many practices. Many health products are used for bleaching teeth, but all side effects are not known. Tooth sensitivity and gingival irritation are the most common side effects, but they are typically mild and transient in nature. The aim of this investigation was to evaluate objectively the effect of 10% carbamide peroxide gel (Opalescence Utradent Inc, USA) on gingival health by measuring changes in Bleeding Index, Plaque Index, and Gingival Index. Eighteen subjects, 11 female and 7 male, age range 15-30 years (mean 24 years), were selected for the study as a convenient sample. Their teeth had either fluorosis, dental stains, smoking, or tetracycline staining. The Opalescence system was used as office monitored, at-home bleaching for three weeks. There was a statistically significant reduction in bleeding on probing (1% - 37%, p < or = 0.003), Plaque Index (4% - 50%, p < or = 0.000), and Gingival Index (2.5% - 34%, p < or = 0.002). Only two subjects reported tooth hypersensitivity, and none of the subjects complained about gingival irritation. There was a positive change in tooth color as far as staining was concerned. Further research including randomized controlled, double blind clinical trials is needed to confirm these findings and to examine other factors related to bleaching of teeth.

PMID: 12595931 [PubMed - indexed for MEDLINE]

Roles of sortase in surface expression of the major protein adhesin P1, saliva-induced aggregation and adherence, and cariogenicity of Streptococcus mutans.

Infect Immun. 2003 Feb;71(2):676-81

Authors: Lee SF, Boran TL

Sortase is a newly discovered transpeptidase that covalently links LPXTGX-containing surface proteins to the gram-positive bacterial cell wall. In this study, the sortase gene (srtA) was isolated from Streptococcus mutans NG8 by PCR. The gene encoded a 246-amino-acid protein, including a 40-amino-acid signal peptide. The srtA gene was insertionally inactivated by a tetracycline resistance cassette. P1, a major surface protein adhesin previously shown to anchor to the peptidoglycan by the LPXTGX motif, was secreted into the culture medium by the srtA mutant. In contrast, the wild-type P1 remained cell wall associated. Complementation of the mutant with srtA restored the P1 surface expression phenotype. P1 produced by the mutant, but not that produced by the wild type and the srtA-complemented mutant, was recognized by an antibody raised against the hydrophobic domain and charged tail C terminal to the LPXTGX motif. These results suggest that the failure to anchor P1 to the cell wall is due to the lack of cleavage of P1 at the LPXTGX motif. The srtA mutant was markedly less hydrophobic than the wild type and the complemented mutant. The srtA mutant failed to aggregate in the presence of saliva or salivary agglutinin and adhered poorly to saliva- or salivary agglutinin-coated hydroxylapatite. In rats, the srtA mutant colonized the teeth poorly when sucrose was absent. When sucrose was present, the srtA mutant colonized the teeth but less effectively and induced significantly less caries (P < 0.05) than the wild-type strain. In conclusion, the sortase enzyme in S. mutans is responsible for anchoring P1 to the cell surface and plays a role in modulating the surface properties and cariogenicity of S. mutans.

PMID: 12540545 [PubMed - indexed for MEDLINE]

Prevalence and antibiotic resistance profile of mercury-resistant oral bacteria from children with and without mercury amalgam fillings.

J Antimicrob Chemother. 2002 May;49(5):777-83

Authors: Pike R, Lucas V, Stapleton P, Gilthorpe MS, Roberts G, Rowbury R, Richards H, Mullany P, Wilson M

Genes encoding resistance to mercury and to antibiotics are often carried on the same mobile genetic element and so it is possible that mercury-containing dental materials may select for bacteria resistant to mercury and to antibiotics. The main aim of this study was to determine whether the prevalence of Hg-resistant oral bacteria was greater in children with mercury amalgam fillings than in those without. A secondary aim was to determine whether the Hg-resistant isolates were also antibiotic resistant. Bacteria in dental plaque and saliva from 41 children with amalgam fillings and 42 children without such fillings were screened for mercury resistance by cultivation on a HgCl(2)-containing medium. Surviving organisms were identified and their susceptibility to mercury and to several antibiotics was determined. Seventy-eight per cent and 74% of children in the amalgam group and amalgam-free group, respectively, harboured Hg-resistant bacteria; this difference was not statistically significant. Nor was there any significant difference between the groups in terms of the proportions of Hg-resistant bacteria in the oral microflora of the children. Of Hg-resistant bacteria, 88% and 92% from the amalgam group and the amalgam-free group, respectively, were streptococci; 41% and 33% were resistant to at least one antibiotic, most frequently tetracycline. The results of this study show that there was no significant difference between children with amalgam fillings and those without such fillings with regard to the prevalence, or the proportion, of Hg-resistant bacteria in their oral microflora. The study also found that Hg-resistant bacteria were common in children regardless of whether or not they had amalgam fillings and that many of these organisms were also resistant to antibiotics.

PMID: 12003971 [PubMed - indexed for MEDLINE]

Composition and antibiotic resistance profile of microcosm dental plaques before and after exposure to tetracycline.

J Antimicrob Chemother. 2002 May;49(5):769-75

Authors: Ready D, Roberts AP, Pratten J, Spratt DA, Wilson M, Mullany P

The aim of this study was to investigate the effects of tetracycline administration on the viability and antibiotic resistance profiles of microcosm dental plaques. A constant depth film fermenter was used to generate multi-species biofilms, which were grown for 216 h before tetracycline was added. The composition of the microcosm plaques was determined by viable counting on selective and non-selective media. The prevalence of antibiotic-resistant organisms was determined on antibiotic-containing media. Before administration of tetracycline, the biofilms had a total viable anaerobic count of 7 x 10(7) cfu per biofilm. They contained 7% lactobacilli, 19% streptococci and 2% Actinomyces spp. Immediately after pulsing with tetracycline, the composition of the biofilms changed and they consisted of 30% lactobacilli, 1.5% streptococci and 3% Actinomyces spp., with a total anaerobic count of 1 x 10(7) cfu per biofilm. The pre-valence and composition of the antibiotic-resistant microflora changed dramatically after the addition of tetracycline, with the proportion of the microflora displaying resistance to tetracycline increasing from 6% to 45%. Corresponding changes in the proportions of the microflora displaying resistance to other antibiotics were as follows: 5-28% for erythromycin, 1-5% for vancomycin and 0.4-3% for ampicillin. The results of this study have shown that the addition of tetracycline to microcosm dental plaques alters their composition and enriches for bacteria resistant to tetracycline and other unrelated agents.

PMID: 12003970 [PubMed - indexed for MEDLINE]

Transfer of TN916-like elements in microcosm dental plaques.

Antimicrob Agents Chemother. 2001 Oct;45(10):2943-6

Authors: Roberts AP, Cheah G, Ready D, Pratten J, Wilson M, Mullany P

Microcosm dental plaques were grown from an inoculum of human saliva in a constant-depth film fermentor. The inoculum contained four tetracycline-resistant streptococcal species, each of which contained a Tn916-like element. This element was shown to transfer to other streptococci both in filter-mating experiments and within the biofilms in the fermentor.

PMID: 11557498 [PubMed - indexed for MEDLINE]

Oral health status and oral health behaviors in Chinese Children.

J Dent Res. 2001 May;80(5):1459-65

Authors: Wong MC, Lo EC, Schwarz E, Zhang HG

The objectives of the study were to describe the oral health status and treatment needs of the 5- to 6-year-old and 12-year-old children in Southern China; to describe the patterns of oral health behaviors, knowledge, and attitudes among the 12-year-olds; and to assess the effects of socio-behavioral factors on the 12-year-old children's dental caries experiences. The study sample was comprised of 1,587 5- to 6-year-old and 1,576 12-year-old urban and rural schoolchildren living in Guangdong Province. Three calibrated dentists clinically examined the children, and trained interviewers interviewed the 12-year-olds. Caries prevalence of the 5- to 6-year-old children was high (urban 78% vs. rural 86%); the mean dmft of the urban and rural children was 4.8 and 7.0, respectively. The caries prevalence and mean DMFT score of the 12-year-olds were 41% and 0.9 (urban) and 42% and 0.9 (rural). Only 2% of the 12-year-olds exhibited no calculus or gingival bleeding, while more than 70% had calculus. In conclusion, there is an urgent need for establishing caries-preventive activities for preschool children. The prevalence of caries among the 12-year-olds was not high, but their periodontal condition was unsatisfactory. Knowledge about gum bleeding and the use of fluoride was low. More oral health education activities should be organized, especially for the rural children.

PMID: 11437220 [PubMed - indexed for MEDLINE]

Efficacy of subantimicrobial dosing with doxycycline. Point/counterpoint.

J Am Dent Assoc. 2001 Apr;132(4):457-66

Authors: Greenstein G, Lamster I

BACKGROUND: This article addresses the role of subantimicrobial dosing with doxycycline, or SDD, in the treatment of chronic periodontitis. The authors discuss and debate 10 issues with regard to SDD's utility as an adjunct to scaling and root planing. TYPES OF STUDIES REVIEWED: The authors reviewed reports of controlled clinical trials that assessed the efficacy of SDD. The main focus of this article is data from the U.S. Food and Drug Administration's phase 3 clinical trial that evaluated the efficacy of SDD in terms of alterations of probing depth, clinical attachment levels and disease progression. RESULTS: The authors compared data from test groups, which underwent root planing plus SDD, with data from control groups, which underwent root planing alone. The mean data suggest that SDD provides a defined but limited improvement of periodontal status when used in conjunction with scaling and root planing. Furthermore, several in vivo studies indicated that a nine-month course of SDD did not cause development of drug-resistant bacterial strains or alteration of the subgingival microbiota. CLINICAL IMPLICATIONS: Some patients may benefit from SDD. However, there are several issues that should be clarified before widespread use of SDD is recommended for patients with chronic periodontitis. The evidence indicates that suppression of the bacterial challenge, which reduces the host response, is the most efficient way to control periodontal diseases.

PMID: 11315376 [PubMed - indexed for MEDLINE]

Discolouration of permanent teeth and enamel hypoplasia due to tetracycline.

Postgrad Med J. 1999 Dec;75(890):772

Authors: Kashyap AS, Sharma HS

PMID: 10755912 [PubMed - indexed for MEDLINE]

Resistance to mercury and antimicrobial agents in Streptococcus mutans isolates from human subjects in relation to exposure to dental amalgam fillings.

Antimicrob Agents Chemother. 2000 Feb;44(2):456-7

Authors: Leistevuo J, J&#xE4;rvinen H, Osterblad M, Leistevuo T, Huovinen P, Tenovuo J

Resistance to cefuroxime, penicillin, tetracycline, and mercury is reported for 839 Streptococcus mutans isolates from 209 human study subjects. The MICs of these drugs did not differ for isolates from one dental amalgam group and two nonamalgam subsets: a group with no known exposure to amalgam and a group whose members had their amalgam fillings removed.

PMID: 10639385 [PubMed - indexed for MEDLINE]

Root-surface caries in rats and humans: inhibition by a non-antimicrobial property of tetracyclines.

Adv Dent Res. 1998 Nov;12(2):43-50

Authors: Ramamurthy NS, Schroeder KL, McNamara TF, Gwinnett AJ, Evans RT, Bosko C, Golub LM

The incidence of root caries has been found to increase as the population ages and as edentulism becomes less prevalent due to improved dental awareness and care, and as exposure of roots due to gingival recession has also increased in the elderly. The mechanism of root caries is thought to be mediated by both bacterial and mammalian proteases produced by plaque and the periodontal tissues, respectively. In the current study, a rat model of periodontal disease was used in which gnotobiotic rats were infected intra-orally with a periodontal pathogen (P. gingivalis). Infecting the rats with P. gingivalis increased the collagenase activity in the gingival tissue in association with severe alveolar bone loss. Treating P. gingivalis-infected rats with doxycycline or CMT-1 prevented the destruction of the periodontium by MMPs, thus preventing exposure of roots to subgingival bacterial plaque and host tissue collagenases and the subsequent development of root caries. In addition, a low-dose doxycycline (LDD, 20 mg bid, non-antimicrobial dose) for 3 months was used in humans predisposed to increased root caries as the result of heavy use of smokeless (chewing) tobacco, causing gingival recession, subgingival plaque accumulation with Gram-negative bacteria, increased gingival crevicular fluid flow (GCF), and elevated GCF collagenase. Daily administration of LDD in smokeless tobacco patients reduced the GCF collagenase and prevented the further development of root caries.

PMID: 9972121 [PubMed - indexed for MEDLINE]

Long-term sub-antimicrobial doxycycline (Periostat) as adjunctive management in adult periodontitis: effects on subgingival bacterial population dynamics.

Adv Dent Res. 1998 Nov;12(2):32-9

Authors: Thomas JG, Metheny RJ, Karakiozis JM, Wetzel JM, Crout RJ

Previous trials had indicated that various schedules of sub-antimicrobial doxycycline significantly reduced gingival crevicular fluid (GCF) collagenase activity in adult patients with periodontitis with no evidence of emergent tetracycline-resistant (Tcr) marker oral flora. The purpose of this nine-month study was to expand these observations, emphasizing newer microbial diagnostic methods. Subgingival paper point samples were obtained at baseline (BL), 3, 6, and 9 months. Four subject treatment groups in a double-blind design were evaluated by mechanical scaling and root planing (SRP) and/or 20 mg doxycycline BID (Periostat). Thirty-eight patients entered the study at baseline (BL). Dark-field microscopy on 260 samples showed that morphotype distribution was independent of treatment schedule. Culture analysis of the 3 most prevalent isolates recovered showed that Streptococcus and Prevotella species accounted for approximately 85% of the 724 cultures. There did not appear to be any overgrowth or replacement by opportunistic oral flora. Of 658 susceptibility patterns evaluated by Etest, the MIC50/90 and mode MIC showed stable patterns, independent of treatment group. Our findings were different from those of previously published reports, but may be partly explained by the lack of universally standardized methods in oral microbiology and interpretive criteria for susceptibility testing.

PMID: 9972119 [PubMed - indexed for MEDLINE]

Greater concentration of dietary sucrose decreases dentin formation and increases the area of dentinal caries in growing rats.

J Nutr. 1997 Nov;127(11):2226-30

Authors: Huumonen S, Tj&#xE4;derhane L, Larmas M

The effect of increasing dietary sucrose concentration on dentin formation and dentinal caries progression was studied. Weanling Wistar rats received 15, 30 or 43 g/100 g sucrose in a diet; for reference, another group was fed a nonpurified diet. At the onset, tetracycline was injected to mark the dentin formed during the experiment. After 6 wk, lower molars were sectioned sagittally; the areas and thicknesses of the dentin formation during the experiment and dentinal caries lesions were quantified separately in the first and second molars. Feeding the 43% sucrose diet resulted in a significantly lower dentin formation than in other diet groups (P < 0.05). The differences obtained from the area measurements were supported by thickness measurements. In the first molar, the 43% sucrose diet resulted in a significantly greater area of dentinal caries than in the other sucrose groups. The number and severity of caries lesions clearly increased as the concentration of sucrose in the diet increased (r = 0.5, P < 0.05 and r = 0.6, P < 0.05, respectively). This study suggests that the increase in the concentration of sucrose in the diet reduces dentin formation and increases the area of dentinal caries as well as the number and severity of caries lesions; the critical sucrose concentration appears to be between 30 and 43 g/100 g.

PMID: 9349851 [PubMed - indexed for MEDLINE]

Combining reconstructive and regenerative therapies.

J Am Dent Assoc. 1997 May;128(5):625-9

Authors: White C, Certosimo AJ

The authors used combined reconstructive and regenerative therapy to treat a patient who had a surgically created osseous defect that also was associated with a perforated root canal. The defect involved a maxillary canine that exhibited 10 millimeters of attachment loss on its mesial surface. Tetracycline root surface conditioning, glass ionomer cement, a decalcified freeze-dried bone allograft and an expanded-polytetrafluorethylene membrane were used to achieve a 7- to 8-mm gain in clinical attachment level two years after the initial surgery. This case illustrates the use of glass ionomer cement, in conjunction with regenerative therapy, to effectively treat a root perforation adjacent to a periodontal osseous defect.

PMID: 9150646 [PubMed - indexed for MEDLINE]

[1354 freshmen's dental investigation]

Shanghai Kou Qiang Yi Xue. 1996 Dec;5(4):198-9

Authors: Zeng L, Gu ZZ, Yan LX, Liu XZ, Hong G

1354 freshmen have been investigated to discover the relationship between dental diseases and environments,living habits and personal sanitary conditions,because urban young men like sweet foods and snacks,the incidence of caries is greater in the cities than in the country,more people with tetracycline discolored tooth live in urban areas than in the rustic ones,which is due to dense living conditions, vulnerable to respiratory organs disease,medical conditions and convenience of taking tetracycline when ill;on the other hand,gingivitis is more common within the country students than within the city students,for those students from the country are used to brush their tooth after adolescence and usually have more dental calculus which is harmful to the gingiva.More than half of the investigated freshmen are ignorant of correct method of brushing and oral health and that is important factors of high rate of dental disease,according to the above reasons,the effective measures should educated to prevent dental disease.

PMID: 15159983 [PubMed - as supplied by publisher]

Tissue response to space closure in monkeys: a comparison of orthodontic magnets and superelastic coil springs.

Eur J Orthod. 1996 Dec;18(6):581-8

Authors: Linder-Aronson A, Forsberg CM, Rygh P, Lindskog S

Interest in using magnets for generating orthodontic forces started with the widespread availability of rare earth magnetic alloys. In vivo studies have indicated that a static magnetic field and/or corrosion products from the magnetic materials may induce biological effects when in close contact with cells or tissues. In the clinical situation, orthodontic magnets are often situated some distance away from the gingiva and bone. Consequently, the previously observed biological effects may not be found in an experimental situation mimicking the clinical setting. Thus, the present experimental study was undertaken to test this hypothesis using commercially available cobalt-samarium magnets for orthodontic treatment in comparison to treatment with Sentalloy closed coil springs with respect to possible side effects on alveolar bone growth, gingival epithelial thickness as well as rate of space closure. Corrosion of the uncovered areas of the magnets was already evident after 6 weeks. No statistical differences were found between the magnet and coil spring specimens with respect to rate of space closure, bone formation or epithelial thickness. The only two variables that differed significantly between magnet and coil spring specimens was that there were more resorption and more tetracycline labelled osteocyte lacunae under the magnets. In conclusion, although some marginal statistical differences were found between the magnet and coil spring specimens with respect to cell and tissue reactions, the near lack of cell and tissue effects of the magnets in the present clinical experimental situation compared to previous studies in which the magnets were positioned in close contact with the tissue under study, indicate limited adverse clinical effects.

PMID: 9009422 [PubMed - indexed for MEDLINE]

Periodontitis vs. peri-implantitis: the same disease? The same treatment?

Crit Rev Oral Biol Med. 1996;7(3):278-91

Authors: Meffert RM

The microbial flora in the natural dentition sulcus/pocket and the implant crevice/pocket is very similar in both health and disease. In health, coccal forms predominate, and in disease, large numbers of Gram-negative pathogens are associated with both tooth and implant. It has also been demonstrated that the bacteria in the partially edentulous implant case may be more pathogenic (especially Gram-negative rods and spirochetes) than in the fully edentulous case, indicating a possible seeding mechanism from tooth pocket to implant crevice. Detoxification procedures involving the use of tetracycline and citric acid prior to regenerative procedures with the use of barrier membranes and grafting materials are necessary, and the same problems attendant to premature exposure of the barrier membrane(s) in the natural dentition situation apply to the implant case. It is apparent that periodontitis = peri-implantitis in etiology and therapy.

PMID: 8909882 [PubMed - indexed for MEDLINE]

Antimicrobial and mercury resistance in aerobic gram-negative bacilli in fecal flora among persons with and without dental amalgam fillings.

Antimicrob Agents Chemother. 1995 Nov;39(11):2499-502

Authors: Osterblad M, Leistevuo J, Leistevuo T, J&#xE4;rvinen H, Pyy L, Tenovuo J, Huovinen P

Antimicrobial resistance is more widespread than can be accounted for as being a consequence of the selection pressure caused by the use of antibiotics alone. In this study, we tested the hypothesis that a high mercury content in feces might select for mercury-resistant bacteria and thus for antimicrobial resistance linked to mercury resistance. Three subject groups with different exposures to dental amalgam fillings were compared. None of the subjects had taken antimicrobial agents during the three preceding months or longer. The group exposed to dental amalgam (n = 92) had 13 times more mercury in feces than the group that had never been exposed to amalgam (n = 43) and the group whose amalgam fillings had been removed (n = 56). No significant differences in either mercury resistance or antibiotic resistance in the fecal aerobic gram-negative flora of these subject groups were seen. The following antimicrobial resistance frequencies were detected with a replica plating method: > or = 1% resistance was seen in 40% of the subjects for ampicillin, 14% of the subjects for cefuroxime, 6% of the subjects for nalidixic acid, 14% of the subjects for trimethoprim, 19% of the subjects for sulfamethoxazole, and 25% of the subjects for tetracycline. The amount of mercury in feces derived from amalgam was not selective for any resistance factors in aerobic gram-negative bacteria, but antimicrobial resistance was widespread even among healthy subjects with no recent exposure to antibiotics.

PMID: 8585733 [PubMed - indexed for MEDLINE]

Evidence that L-(+)-lactate dehydrogenase deficiency is lethal in Streptococcus mutans.

Infect Immun. 1994 Jan;62(1):60-4

Authors: Hillman JD, Chen A, Duncan M, Lee SW

In order to construct an effector strain for the replacement therapy of dental caries, we wished to combine the properties of low-level acid production and high-level colonization potential in a strain of Streptococcus mutans. To this end, we made a deletion in the lactate dehydrogenase (LDH) gene cloned from the bacteriocin-producing S. mutans strain JH1000. However, we were unable to substitute the mutant for the wild-type allele by transformation with linear DNA fragments. The mutated gene, carried on a suicide vector, was shown by Southern analysis to integrate into the JH1000 chromosome to yield transformants carrying both the wild-type gene and mutated LDH gene. Three spontaneous self-recombinants of one heterodiploid strain were isolated by screening 1,500 colonies for a loss of the tetracycline resistance encoded by the gene used to mark the LDH deletion. In all three cases, Southern analysis showed that a loss of tetracycline resistance was accompanied by a loss of the mutated LDH gene, resulting in restoration of the wild-type genotype. However, screening the same number of colonies for self-recombinants that did not make lactic acid during anaerobic growth in Todd-Hewitt broth failed to identify clones in which the wild-type allele was lost. A second, simpler screening of more than 80,000 colonies grown aerobically on glucose tetrazolium medium to identify low-level-acid-producing colonies was also unsuccessful. These results are interpreted as indicating that LDH deficiency is lethal in S. mutans under the cultivation conditions used in these experiments. The physiological bases for this hypothesis are described.

PMID: 8262650 [PubMed - indexed for MEDLINE]

Dentin caries recording with Schiff's reagent, fluorescence, and back-scattered electron image.

J Dent Res. 1993 Dec;72(12):1588-92

Authors: Hietala EL, Tj&#xE4;derhane L, Larmas M

After being weaned, the Wistar rats (12) were fed on a sucrose diet for five weeks to induce dental caries. Tetracycline was injected intraperitoneally into 7 of them to label the mineralizing dentin front. Five rats without tetracycline injection were used to verify spontaneous fluorescence. The evidently carious area under one prominent fissure from each mandibular molar hemisected sagittally in the midline was photographed under ultraviolet light so that autofluorescence would be revealed. The jaws were then stained with Schiff's reagent and photographed under normal light and again under ultraviolet light. The areas of all the lesions were quantified planimetrically as they appeared on the photographs. The mineral contents of the areas were verified with the back-scattered electron images. The caries lesions revealed with Schiff's reagent also exhibited a change in the color of the dentin fluorescence regardless of the tetracycline labeling. The areas of these lesions followed the shapes of the lesions stained by Schiff's reagent but they were greater. Staining with Schiff's reagent was repeatable after the specimen was washed with ethanol for a few weeks. The loss of minerals was seen in the areas stained with Schiff's reaction but was also related to the change in dentin fluorescence, which seems to be a more sensitive indicator of the caries progression than Schiff's reagent, especially in the early phase of the carious process.

PMID: 8254127 [PubMed - indexed for MEDLINE]

Mercury released from dental "silver" fillings provokes an increase in mercury- and antibiotic-resistant bacteria in oral and intestinal floras of primates.

Antimicrob Agents Chemother. 1993 Apr;37(4):825-34

Authors: Summers AO, Wireman J, Vimy MJ, Lorscheider FL, Marshall B, Levy SB, Bennett S, Billard L

In a survey of 640 human subjects, a subgroup of 356 persons without recent exposure to antibiotics demonstrated that those with a high prevalence of Hg resistance in their intestinal floras were significantly more likely to also have resistance to two or more antibiotics. This observation led us to consider the possibility that mercury released from amalgam ("silver") dental restorations might be a selective agent for both mercury- and antibiotic-resistant bacteria in the oral and intestinal floras of primates. Resistances to mercury and to several antibiotics were examined in the oral and intestinal floras of six adult monkeys prior to the installation of amalgam fillings, during the time they were in place, and after replacement of the amalgam fillings with glass ionomer fillings (in four of the monkeys). The monkeys were fed an antibiotic-free diet, and fecal mercury concentrations were monitored. There was a statistically significant increase in the incidence of mercury-resistant bacteria during the 5 weeks following installation of the amalgam fillings and during the 5 weeks immediately following their replacement with glass ionomer fillings. These peaks in incidence of mercury-resistant bacteria correlated with peaks of Hg elimination (as high as 1 mM in the feces) immediately following amalgam placement and immediately after replacement of the amalgam fillings. Representative mercury-resistant isolates of three selected bacterial families (oral streptococci, members of the family Enterobacteriaceae, and enterococci) were also resistant to one or more antibiotics, including ampicillin, tetracycline, streptomycin, kanamycin, and chloramphenicol. While such mercury- and antibiotic-resistant isolates among the staphylococci, the enterococci, and members of the family Enterobacteriaceae have been described, this is the first report of mercury resistance in the oral streptococci. Many of the enterobacterial strains were able to transfer mercury and antibiotic resistances together to laboratory bacterial recipients, suggesting that the loci for these resistances are genetically linked. Our findings indicate that mercury released from amalgam fillings can cause an enrichment of mercury resistance plasmids in the normal bacterial floras of primates. Many of these plasmids also carry antibiotic resistance, implicating the exposure to mercury from dental amalgams in an increased incidence of multiple antibiotic resistance plasmids in the normal floras of nonmedicated subjects.

PMID: 8280208 [PubMed - indexed for MEDLINE]

Detection of conjugal transfer systems in oral, black-pigmented Bacteroides spp.

J Bacteriol. 1990 Jan;172(1):495-7

Authors: Guiney DG, Bouic K

Oral, black-pigmented Bacteroides spp. are important pathogens in oral anaerobic infections and dental disease. We detected conjugation systems in isolates of Bacteroides denticola and Bacteroides intermedius that transferred tetracycline resistance (Tetr) and penicillin resistance to Bacteroides buccae and to Bacteroides fragilis, an intestinal Bacteroides species. A cloned Tetr gene from B. fragilis hybridized to the transferable Tetr locus in the oral strains, indicating that genetic exchange occurs between these two groups of anaerobes.

PMID: 2294095 [PubMed - indexed for MEDLINE]

Nucleotide sequence analysis of tetracycline resistance gene tetO from Streptococcus mutans DL5.

J Bacteriol. 1988 Aug;170(8):3618-26

Authors: LeBlanc DJ, Lee LN, Titmas BM, Smith CJ, Tenover FC

Streptococcus mutans DL5, isolated from the dental plaque of a pig, was resistant to high levels of streptomycin (Sm, 20 mg/ml), erythromycin (Em, 1 mg/ml), and tetracycline (Tc, greater than 100 micrograms/ml), but contained no detectable plasmid DNA. The Smr and Emr determinants were cloned from cellular DNA on the self-replicating 5-kilobase-pair (kbp) EcoRI fragment of pAM beta 1 and the 4.2-kbp cryptic plasmid pVA380-1, respectively, by transformation of Streptococcus sanguis Challis. Helper plasmid cloning, with a Challis host containing pVA380-1, was required to clone the Tcr determinant of strain DL5 on this vector. A single-colony isolate of the original Tcr clone contained a hybrid plasmid, pDL421, composed of 2.6 kbp of vector DNA and 11.4 kbp of S. mutans DNA. Plasmid pDL421 did not hybridize to plasmids containing the streptococcal Tcr determinants tetL, tetM, and tetN. A shortened derivative of this hybrid plasmid, pDL422, missing a 4.9-kbp HincII fragment from the S. mutans DNA but still encoding Tcr, was obtained by subcloning in S. sanguis Challis. The Tcr gene was located in a 1,917-base-pair open reading frame (ORF) corresponding to a 72-kilodalton protein. The ORF exhibited 99.4% sequence identity with the 1,917-base-pair tetO gene from a strain of Campylobacter coli (W. Sougakoff, B. Papadopoulou, P. Nordmann, and P. Courvalin, FEMS Microbiol. Lett. 44:153-160, 1987). A 1.67-kbp NdeI fragment, internal to the ORF from strain DL5, as well as pDL421 hybridized under stringent conditions to DNA from 10 of 10 Tcr strains of C. coli and Campylobacter jejuni from human and animal sources, but not to DNA from Tcs isolates of these two species.

PMID: 2841293 [PubMed - indexed for MEDLINE]

Cost-effectiveness analysis of periodontal disease control.

J Dent Res. 1987 Nov;66(11):1630-5

Authors: Antczak-Bouckoms AA, Weinstein MC

Cost-effectiveness analysis was used to evaluate alternative methods of periodontal disease control. The alternatives considered included non-surgical and surgical procedures as well as the use of antimicrobial agents. Data on costs were obtained from American Dental Association publications of average charges for periodontal services. The concept of quality-adjusted tooth-years (QATYs) was developed to provide an outcome measure which could be compared across treatments. The conclusions of this analysis are as follows: (1) Conservative non-surgical treatments for periodontal disease control not only have costs lower than surgical alternatives, as would be expected, but also maximize expected quality-adjusted tooth-years over a wide range of estimates; (2) antimicrobial therapy used as an adjunct to non-surgical treatment is likely to be both effective and cost-effective; and (3) quality of tooth-years is a critical consideration in the determination of outcome of periodontal treatment. For example, when tooth-years are not adjusted for quality, differences between treatments are diminished, and surgical treatment becomes as good as or better than more conservative treatments for some levels of disease severity.

PMID: 10872396 [PubMed - indexed for MEDLINE]

Dental fluorosis developed in post-secretory enamel.

J Dent Res. 1986 Dec;65(12):1406-9

Authors: Richards A, Kragstrup J, Josephsen K, Fejerskov O

The aim of this study was to test whether dental fluorosis can be produced by administration of chronic doses of fluoride during only the post-secretory stage of enamel mineralization. Eight control and eight experimental pigs matched by weight and litter were fed a low-fluoride diet (less than 0.05 mg F-/kg b.w. daily) from weaning to slaughter at 14 months. The test group received an oral dose of 2 mg F-/kg b.w. per day from 8 months of age. Lower fourth pre-molars were at the post-secretory stage at the start of fluoride administration (confirmed by tetracycline marker) and were just erupting at slaughter. All of the fourth pre-molar teeth from the test group developed diffuse enamel hypomineralization indistinguishable from human fluorosis. No such lesions were seen in any of the teeth from the control animals. It was concluded that enamel fluorosis may be caused by fluoride exposure in the maturation phase only. The pathogenic mechanism may be an effect either on the selective loss of protein or on the influx of mineral, both of which occur during the post-secretory or maturation stage of enamel formation.

PMID: 3465769 [PubMed - indexed for MEDLINE]

Colonization of the human oral cavity by a strain of Streptococcus mutans.

J Dent Res. 1985 Nov;64(11):1272-4

Authors: Hillman JD, Yaphe BI, Johnson KP

Streptococcus mutans strain JH1001 produces a bacteriocin that can kill virtually all other strains of this micro-organism. The ability of JH1001 to colonize the human oral cavity was tested in a study involving five subjects and three different infection regimens, all of which involved multiple exposures to large numbers of organisms. Two and one-half years after infection, JH1001 was found to have persistently colonized three of the subjects. The indigenous S. mutans in one subject were reduced below the level of detection. Levels of (total) S. mutans and S. sanguis were not affected in persistently colonized subjects. Mutants of indigenous S. mutans resistant to the bacteriocin were not observed. The results indicate the importance of host variability and infection regimen for superinfection by this strain of S. mutans. The efficient replacement of indigenous S. mutans by JH1001 in one subject lends support to the eventual application of replacement therapy to the prevention of dental caries.

PMID: 3912416 [PubMed - indexed for MEDLINE]

Dental caries and tetracycline-stained dentition in an American Indian population.

J Dent Res. 1985 Mar;64(3):462-4

Authors: Rebich T, Kumar J, Brustman B

Complaints of enamel defects in American Indian children residing on the St. Regis reservation in New York State prompted an epidemiological study. The results of that study, reported earlier (Rebich et al., 1983), indicated that over one-fifth of the American Indian children had discoloration of the dentition due to ingestion of tetracycline during the years of tooth formation. These data also provided an ideal opportunity to examine the link between tetracycline staining and caries which has been postulated by previous authors. American Indian children, ages 7-18, were found to have a higher caries experience than other children and a lower rate of dental service utilization, as evidenced by the filled component of the DMFS index (FS/DMFS). Within the American Indian population, however, no indication was found of any association between tetracycline staining and dental caries.

PMID: 3855899 [PubMed - indexed for MEDLINE]

Systematic assessment of color removal following vital bleaching of intrinsically stained teeth.

J Dent Res. 1985 Mar;64(3):457-61

Authors: Seale NS, Thrash WJ

Various treatment variables associated with a standard bleaching technique were systematically recorded in 53 individuals exhibiting intrinsic discoloration of permanent teeth. These variables (predictors) included: (1) etiology (fluoride or tetracycline); (2) age of the patient; (3) the presented color of the stain; (4) the intensity of that color; (5) a long versus short bleaching time technique; and (6) the number of bleaching sessions. These were assessed as to their relationship with the results of treatment (dependent variable). The findings of a multiple regression analysis revealed that the contributions of the individual predictors were significantly different between those stains caused by tetracycline ingestion (N = 27) and those stains due to fluoride ingestion (N = 20). The analysis also revealed that those variables contributing to a significant proportion of the variance in results of treatment when tetracycline was the cause were: (1) the color of the stain and (2) the number of bleaching sessions. When fluoride was apparently the causal agent: (1) the bleaching time technique; (2) age of the patient; (3) color of the stain; and (4) the number of bleaching sessions contributed to a significant proportion of the variance in the results of treatment.

PMID: 3855898 [PubMed - indexed for MEDLINE]

A conjugative transposon (Tn919) in Streptococcus sanguis.

Infect Immun. 1985 Feb;47(2):415-20

Authors: Fitzgerald GF, Clewell DB

Streptococcus sanguis FC1, originally isolated from dental plaque, was found to be naturally resistant to tetracycline. Although no plasmid DNA could be detected, tetracycline resistance was transferable in filter matings to Streptococcus faecalis FA2-2. Again, no plasmid DNA was detectable in transconjugants, and the latter could donate tetracycline resistance to S. faecalis, S. sanguis, and Streptococcus lactis. The tetracycline resistance element was able to transpose to several sites on the S. faecalis hemolysin plasmid pAD1 and in each case resulted in a 15-kilobase insert. DNA filter blot hybridization studies showed that the element bears significant homology with the conjugative transposon Tn916. Designated Tn919, it was cloned into an Escherichia coli plasmid vector (pGL101) and, as has been shown for Tn916, excised readily in the absence of selective pressure.

PMID: 2981772 [PubMed - indexed for MEDLINE]

Antibacterial susceptibility of plaque bacteria.

J Dent Res. 1979 Jul;58(7):1722-32

Authors: Newman MG, Hulem C, Colgate J, Anselmo C

Selected anaerobic, capnophilic and facultative bacteria isolated from patients with various forms of periodontal health and disease were tested for their susceptibility to antibiotics and antimicrobial agents. Specific bactericidal and minimum inhibitory concentrations were compared to disc zone diameters, thereby generating new standards for the potential selection of antimicrobial agents.

PMID: 286720 [PubMed - indexed for MEDLINE]

Antibiotic susceptibility of Streptococcus mutans: comparison of serotype profiles.

Antimicrob Agents Chemother. 1979 Mar;15(3):440-3

Authors: Little WA, Thomson LA, Bowen WH

A total of 82 strains of Streptococcus mutans representing serotypes a through g were tested for susceptibility to erythromycin, penicillin, methicillin, lincomycin, tetracycline, vancomycin, gentamicin, streptomycin, neomycin, kanamycin, bacitracin, and polymyxin B. Strains included stock cultures and isolates from human and animal dental plaque. Minimal inhibitory concentrations were determined by a broth-microdilution procedure. The major differences in antibiotic susceptibility observed among the serotypes resulted with antibiotics which act on the cell surface. Bacitracin was most active against serotype a strains and polymyxin B against serotype b strains. Serotypes a, d, and g were less susceptible than the other serotypes to methicillin.

PMID: 464571 [PubMed - indexed for MEDLINE]

Endocarditis due to strain of Cardiobacterium hominis resistant to erythromycin and vancomycin.

Chest. 1979 Jan;75(1):85-6

Authors: Prior RB, Spagna VA, Perkins RL

Endocarditis caused by Cardiobacterium hominis was observed in a penicillin-allergic patient with a prosthetic cardiac valve who had received prophylactic therapy with erythromycin for dental extractions. The organism was resistant to erythromycin and vancomycin, with minimal inhibitory concentrations of 12.5 microgram/ml and 25 microgram/ml, respectively, but was sensitive to penicillin G, tetracycline, cephalexin, and cefaclor. This case suggests that currently recommended antibiotic prophylactic therapy for endocarditis, especially in penicillin-allergic patients, may be inadequate for unusual pathogens such as C hominis.

PMID: 253635 [PubMed - indexed for MEDLINE]

In vitro studies of the phenomenon of tetracycline incorporation into enamel.

J Dent Res. 1977 Dec;56(12):1527-32

Authors: Lambrou DB, Tahos BS, Lambrou KD

Incorporation of tetracyline into dental enamels was studied by exposing presoftened enamel slabs to tetracycline-containing mineralizing solutions. Tetracycline was incorporated only when remineralization (assessed by hardness) occurred and the experimental conditions favored the formation of a soluble tetracycline Ca complex. The fluorescence induced by tetracycline incorporation into the enamel slabs was comparable to that reported under in vivo conditions.

PMID: 277475 [PubMed - indexed for MEDLINE]

Analysis of plasmid deoxyribonucleic acid in a cariogenic strain of Streptococcus faecalis: an approach to identifying genetic determinants on cryptic plasmids.

J Bacteriol. 1977 May;130(2):759-65

Authors: Oliver DR, Brown BL, Clewell DB

Streptococcus faecalis strains ND539 and OG1 have been previously shown to be cariogenic in gnotobiotic animals. Deoxyribonucleic acid analyses have revealed the presence of a single 26-megadalton plasmid designated pAM539 in the former strain, whereas the latter strain was found to be plasmid-free. By gene transfer experiments, it was possible to construct isogenic pairs of strains that differed only with regard to the presence or absence of pAM539. Comparative studies of isogenic pairs showed that the presence of pAM539 conferred bacterial sensitivity to a bacteriocin produced by S. faecalis strain 5952.

PMID: 122512 [PubMed - indexed for MEDLINE]