动物源性链球菌红霉素耐药基因的分布

致病性链球菌可导致人和动物的各种化脓性疾病、肺炎、乳腺炎、败血症等，且部分致病性链球菌是重要的人畜共患病病原，对人畜健康均造成极大危害，已引起高度重视。大环内酯类抗生素作为青霉素药物的替代药物是治疗致病性链球菌感染的有效药物。国内外对人医重要的链球菌诸如肺炎球菌、化脓性链球菌的研究表明，临床分离株对大环内酯类抗生素的耐药率较高，

Erythromycin Resistance Mechanisms in Streptococcus Isolates from Animals

To investigate the mechanisms of erythromycin-resisant streptococcus isolated from animals,the minimal inhibitory concentrations(MICs) of pencillin, erythromycin and clindamycin against streptococcus were detected by agar two-fold dilution, the resistance phenotypes of erythromycin-resistant streptococcus were determined by the double disk test, and the presence of mefA, ermB genes were determined by PCR amplification. The results showed that the rate of resistance to penicillin, erythromycin and clindamycin of 111 strains studied were 54.95%,68.47%and 64.86%,respectively. In 76 erythromycin resistant strains, 62 isolates (81.58%) were assigned to the cMLS_B phenotype, 5 isolates (6.6%) were M phenotype and 9 isolates (11.84%) were inducibly resistant, expressing the iMLS_B phenotype by the double disk test. The mefA gene was present in all of the strains showing the M-resistance phenotype. Some isolates expressing a cMLS_B phenotype and iMLSB phenotype were confirmed genotypically by the presence of the ermB gene, but 6 isolates were n't detected the ermB and mefA gene. Genes coding for both resistance mechanisms were found in one strain. No amplification was detected in all the erythromycin susceptible streptococcus isolates. Erythromycin resistant Streptococcus isolated from animals mediated by ermB was predominant in China. The PCR amplification can be a useful method to rapidly screen the erythromycin resistant strains.