Identification And Antibiotic Resistance Of Prevotella Species Isolated From Periodontal Abscess

Objective:The study aims to provide scientific basis of antibiotic treatment for periodontal abscesses by isolating and culturing predominant anaerobes from the periodontal abscesses, performing antibiotic susceptibility test and detecting drug resistant genes of the strains.Methods:1.41periodontal abscesses patients, including21male and20female, were enrolled in the study.41periodontal abscesses samples were collected and cultured on selective and non-selective culture media. After verifying bacteria tolerance of oxygen for2-3times, strict anaerobes were isolated from primary culture. The strains were then identified by both API20a biochemical method and16S rRNA method to further screening for Prevotella species.2. The antibiotic susceptibility test to8antibiotic, including metronidazole, cefradine, cefixime amoxicillin, clindamycin, roxithromycin, doxycycline and imipenem, were performed by agar dilution method, according to the Clinical Laboratory Standards Institution(CLSI2012).3. PCR assays were performed to detect the presence of drug resistance genes of ermF, tetQ,nim and cfxA.Results:1. A total of59different bacterial colonies were isolated and identified.42strains were of Prevotella genus.2. All the Prevotella species were sensitive to imipenem and presented low resistant rate to doxycycillin, with4.8%. In the Prevotella species, the resistant rate to clindamycin were as high as38.1%.30.9%and26.2%of Prevotella species were resistant to amoxycillin and roxithromycin, respectively. The resistant rate of metronidazole was9.5%as well as that of cefixime. 3. In Prevotella species, about68.4%strains were detected with ermF gene and61.5%amoxycillin-resistant strains were detected with cfxcA gene. Two nim genes found in four metronidazole-resistant Prevotella species, were identified as nimBConclusion:1. In our research, Prevotella species were the most frequently isolated bacteria from periodontal abscesses. There was a great discrepancy in the methods of API20a and16S rRNA identifying anaerobic bacteria.2. Our results alarm high resistant rate of clindamycin and roxithromycin, which makes its use unacceptable for the empiric therapy of periodontal abscess. The use of macrolides and lincomycins should be under monitoring in treating periodontal abscess. Meanwhile, the concern of reduced susceptibility to penicillins and metronidazole should be raised.3. We also demonstrate a brief prevalence of antimicrobial resistance genes in anaerobic bacteria we isolated. The detection rate of cfxA gene and ermF gene were high in resistant Prevotella species.