高水平莫匹罗星耐药MRSA体外生物膜形成能力及相关基因检测

Analysis of in vitro biofilm formation and biofilm-associated genes of high-level mupirocin-resistant,methicillin-resistant Staphylococcus aureus isolates

目的了解高水平莫匹罗星耐药甲氧西林耐药金葡菌(MuH MRSA)体外生物膜形成能力及介导生物膜形成相关基因的分布。方法对分离自上海和浙江省温州地区5所教学医院的803株临床分离MRSA进行莫匹罗星纸片扩散法检测最低抑菌浓度(MIC),mupA基因PCR扩增筛选MuH MRSA,分光光度计检测MuH MRSA菌株体外生物膜的形成能力,PCR扩增生物膜形成相关基因(icaA、icaD、agr、sarA、sasG、bap和ccpA)。结果共筛选出53株MuH MRSA,其中仅5株(9.4%,5/53)具有体外形成生物膜的能力;基因检测显示,icaD和agr基因存在于全部MuH MRSA菌株中,而icaA、sarA、sasG和ccpA基因则分别存在于83.0%、86.8%、84.9%和92.5%的菌株中,仅有1株细菌携带bap基因。结论大部分生物膜形成相关基因广泛分布于MuH MRSA菌株中,但仅agr基因可能是该类菌株体外生物膜形成能力的主要影响因素。

Objective To explore the ability of in vitro biofilm formation of high-level mupirocin-resistant,methicillin-resistant Staphylococcus aureus（MuH MRSA） isolates and the prevalence of biofilm-associated genes.Methods MuH MRSA isolates were screened by mupirocin disc diffusion,minimum inhibitory concentration（MIC） and the polymerase chain reaction（PCR） amplification of mupA gene from 803 clinical MRSA isolates obtained from Shanghai and Wenzhou.The biofilm-forming ability of MuH MRSA was tested using a spectrophotometric quantitative assay.The biofilm-associated genes（icaA,icaD,agr,sarA,sasG,bap and ccpA） were amplified by PCR.Results A total of 53 strains of MuH MRSA were identified.Only 5（9.4%,5/53） were able to form biofilm.The icaD gene and agr operon were identified in all the MuH MRSA strains.The genes icaA,sarA,sasG and ccpA were harbored by 83.0%,86.8%,84.9% and 92.5% of the isolates,respectively.However,the bap gene was only hosted by one isolate.Conclusions Most biofilm-associated determinants were prevalent in MuH MRSA isolates.However,only agr operon was the gene which might affect the biofilm-forming ability of this pathogen.