Drug Resistance Of Predominant Periodontal Abscesses Anaerobes

Objective:The study aims to provide scientific basis of antibiotic treatment for periodontal abscesses at the molecular level by isolating and culturing predominant anaerobes from the periodontal abscesses, performing antibiotic susceptibility test and detecting drug resistant genes of the strains.Methods:1.58periodontal abscesses patients, including23male and35female, were enrolled in the study. The periodontal abscesses samples were collected and cultured with anaerobic bags. After verified two to three times sensitive to oxygen, the single colonies of the periodontal anaerobes were isolated and preserved. The strains were then identified by both API20A Biochemical method and16S PCR method.2.The antibiotic susceptibility test to8antibiotic, including metronidazole, cefoxitin, cefmetazole, clindamycin, chloramphenicol, roxithromycin, doxycycline and Imipenem, were performed by agar dilution method, According to the National Committee for Clinical Laboratory Standards (NCCLS, Mll-A5).3. The resistant genes of the drug-resistant strains obtained were screened by PCR.Results:1. GEN bag Method had good performance on isolating and detecting anaerobes. The anaerobes were detected in48.3%of the samples and Prevotella melaninogenica was identified the upmostly. API20A biochemical method had82%agreement with the16S PCR method in identification.2. The results demonstrated that the resistant rate of the isolates to metronidazole, clindamycin and cefmetazole were8%,36%and4%respectively. Whereas, no strain was detected resistant to imipenem, chloramphenicol or cefoxitin.3. The ermF gene were detected in three of eight clindamycin resistant strains. None of them was found coded on bacterial plasmids. However, no metronidazole resistant gene was detected on drug resistant strains.Conclusion:1. P.melaninogenica was the predominant species dectected in the periodontal abscess of the patients.2. There was discrepancy between periodontal anaerobies resistant to the antimicrobial drugs. Although metronidazole is commonly used as treatment of infections due to anaerobes, resistant to metronidazole had become increasingly. The use of antibiotic agents should base on the genotypes and antimicrobial susceptibility testing.3. No known resistacne genes was detected in the metronidale resistant strains. Since anaerobes may have complex drug resistant mechanisms resulting from interaction of the resistance genes, other mechanism may exist and remains to be explored.