耐甲氧西林葡萄球菌HVR基因分型及其与耐药性的关系

目的 为获得成都地区耐甲氧西林葡萄球菌的HVR－PCR基因型，比较HVR基因型与耐药谱的关系，从而指导临床合理选用抗生素，并初步探讨其在分子流行病学分析中的作用。方法 从成都地区四家三甲医院收集到临床分离的葡萄球菌114株。其中86株MRSA、10株MRSE（Mc‘S.epidemidis)、5株MSSE（Mc‘S.epidemidis)、8株MRSH（Mc‘S.haemolyticus)和5株MSSH（Mc‘S.haemolyticus)。用琼脂平皿二倍稀释法测定其MIC值，优良的碱裂解法提取DNA，应用PCR技术，扩增mec基因高变区（HVR区），聚丙烯酰胺凝胶垂直板和琼脂糖凝胶电泳分型。结果 根据PCR产物片段大小，MRSA、MRSE和MRSH分别被分为4种、3种和2种基因型，其中有9株MRSE的PCR扩增产物片段大小与MRSA相同。MRSA主要为A、D型，分别占52．32％和39．53％；B、C型最为耐药，而D型对多种药物敏感。MRSE的Ⅰ型为高度多重耐药株，而Ⅲ型对多种抗生素敏感。MRSH的a型比b型耐药。结论 HVR－PCR法对于由MRSA引起的院内感染的流行病学调查是一种快速、简单、可靠的分型法，且有利于抗菌药物的选用。这种方法能够部分比较MRSA菌株和耐甲氧西林的凝固酶阴性葡萄球菌（Mc‘CNSt)的mec决定因子，从而探讨其起源。

The HVR genotypes and their relationship with the resistance of methicillin-resistant staphylococci]

OBJECTIVE: To investigate the HVR-PCR genotype of methicillin-resistant Staphylococci in local hospitals and compare it with the antibiograms, with aview to selecting effective antibacterial agents, moreover, to discuss preliminarily its role in molecular epidemiology. METHODS: The minimal inhibitory concentrations(MICs) of 86 MRSA, 10 MRSE(Mc'S. epidemidis), 5 MSSE(Mc'S. epidemidis), 8 MRSH(Mc'S. haemolyticus) and 5 MSSH(Mc'S. haemolyticus) clinical isolates collected from 4 local hospitals were tested by serial two-fold agar dilution method; their DNA were extracted by moved basic lytic method, whose polymerase chain reaction(PCR) products amplified, based on the size of mec-associated hypervariable region(HVR) were analyzed by PAG vertical and agarose gel electrophoresis. RESULTS: MRSA, MRSE and MRSH were grouped into 4, 3 and 2 HVR genotypes respectively according to the size of the PCR products. The PCR products amplified from 9 of 10 MRSE isolates were the same as the products amplified from MRSA isolates. MRSA strains in this study were mainly HVR genotypes A and D, which accounted for 52.32% and 39.53%; Genotypes B and C were the most multi-drug resistant, but genotype D was multi-sensitive. The I genotype of MRSE was multi-drug resistant, but its genotype III was multi-drug sensitive. The genotype a of MRSH was more resistant than genotype b. CONCLUSION: These results suggest that HVR-PCR genotype method is an easy and fast method for epidemiological investigation of nosocomial infections caused by MRSA, and it is helpful for clinical selection of antibacterial agents. This method can compare the mec determinants of MRSA and Mc'CNSt isolates and hence to search for the origin of the mec determinant.