Abstract： Objective To isolate and culture the predominant anaerobes from the periodontal abscesses,and to test the antibiotic susceptibility and drug resistant genes of the strains.Methods The isolated strains were identified by both API20A biochemical method and polymerase chain reaction (PCR) method.The antibiotic susceptibility test was performed by agar dilution method.The resistant genes of the drug-resistant strains obtained were screened by PCR.Results The anaerobes were detected in 48％ (28/58) of the samples and Prevotella melaninogenica(Pm) was mostly identified in 43％ (12/28).APL20A biochemical method had 82％ (23/28) agreement with the 16SrRNA method in identification rate.Anaerobes were resistant to metronidazole,clindamycin and cefmetazole.The erythromycin-resistant methylase genes F(ermF) gene was 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.Conclusions Pm was the predominant species dectected in the periodontal abscess of the patients.The antibiotic agents should be used based on the genotypes and general condition of the patients.