健康人携带金黄色葡萄球菌耐药表型及基因型研究

目的 调查我国健康人携带的金黄色葡萄球菌药物敏感性及大环内酯类耐药基因分布情况.方法 应用E-test方法,对2009－2011年收集的100株健康从业人员携带菌株进行16种抗生素的药物敏感性分析,以D 试验测定红霉素对克林霉素的诱导耐药表型.采用spa分型对上述菌株进行分型分析.利用PCR检测基因:甲基化酶erm(A),erm(B),erm(C),erm(F),erm(T),erm(Y),erm(33)和erm(G)]、ATP结合转运蛋白msr(A)和msr(D)]、主要易化子mef(A)]、酯酶ere(A)]及磷酸化酶mph(C)],并与猪来源菌株38株(31株MRSA,7株MSSA)和患者来源MRSA菌株20株进行比较.结果 健康人群携带菌株对红霉素和克林霉素耐药率较高,分别为52%和27%.克林霉素诱导耐药率为29%.共鉴定35个spa型别,其中51.0%的spa型别为t189、t571、t002、t796、t437、t034和t701.52株健康人菌株主要携带erm(C)(57.7%)和erm(B)(34.6%), 95.0%的临床分离菌株携带erm(A), 100.0%猪鼻拭子分离菌株均携带erm(C)菌株.结论 携带erm(C)和erm(B)耐药基因的大环内酯类耐药菌株在健康人群中广泛存在,这些耐药基因在金黄色葡萄球菌中呈散在克隆传播.

Phenotype and genotype of antimicrobial resistance on nasal Staphylococcus aureus isolates from healthy people

Objective To investigate the antimicrobial susceptibility and molecular nature related to the resistance on macrolides from nasal Staphylococcus(S.) aureus isolates among healthy people. Methods A total of 100 S. aureus isolates collected from 2009 to 2011 were tested for antimicrobial susceptibility by E-test. Double disc test (D-test) was used to detect the inducible clindamycin resistance. All S. aureus isolates were characterized by spa typing. Macrolides resistance genes were detected and compared with isolates that were collected clinically or from the livestock. Results High resistance rates on erythromycin or clindamycin was noticed,with 52% and 27% ,respectively. Inducible clindamycin resistance was identified in 29 of the 100 (29%) isolates. In total,the 100 isolates were assigned to 35 spa types. The most common spa types were found to be t189,t571,t002,t796,t437,t034 and t701,that accounted for 51.0% of all the isolates. erm(C) (57.7% ) and erm (B)(34.6%) were found as the dominant genes in 52 S. aureus isolates from healthy people. On the other hand,erm(A) and erm(C) were identified in 95.0% S. aureus isolates from patients and all the livestock,respectively. Conclusion erm(C) and erm(B) carrying S. aureus strains were circulating in healthy people and these genes were distributed in different S. aureus clones.