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目的研究儿童社区获得性耐甲氧西林金黄色葡萄球菌(CA-MRSA)肺炎临床分离株的分子特征、耐药性及Panton-Valentine杀白细胞素(PVL)基因携带情况。方法 2006—2012年国内8家儿童医院在CA-MRSA肺炎患儿中分离出76株菌株;用PCR方法检测PVL基因;对所有菌株进行MLST、spa和SCCmec分型;采用琼脂稀释法进行14种抗生素的体外药物敏感试验。结果 76株CA-MRSA分离株中有32株(42.1%)携带PVL基因。在11种MLST型中,ST59(44.7%)是最主要的ST型;在17种spa型中,以t437(46.1%)为主;共有2种SCCmec型,以Ⅳ(82.9%)为主。CA-MRSA对红霉素和克林霉素的耐药率分别为86.9%和72.4%。PVL阳性菌株对庆大霉素的耐药率高于PVL阴性菌株,差异有统计学意义(53.1%比25.0%,P=0.012)。5例坏死性肺炎中4例分离株为PVL阳性T910-MRSA-Ⅳa-t318,1例为PVL阴性ST398-MRSA-Ⅴ-t034。结论 ST59-MRSA-Ⅳa-t437是儿童CA-MRSA肺炎分离株的主要流行克隆,未发现PVL与坏死性肺炎有相关性,但PVL阳性ST910-MRSA-Ⅳa-t318菌株与坏死性肺炎有关。CA-MRSA肺炎分离株对红霉素和克林霉素有较高的耐药性。
Objective To investigate the molecular characteristics, drug resistance and the carrying status of Panton-Valentine Leukocyte Cytokinin (PVL) gene in clinical isolates of community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) in children. Methods 76 strains of children were isolated from children with CA-MRSA pneumonia in 8 children’s hospitals in China from 2006 to 2012. The PVL gene was detected by PCR method. MLST, spa and SCCmec typing were performed on all the strains. Fourteen strains were screened by agar dilution method. In vitro drug sensitivity test of antibiotics. Results 32 out of 76 CA-MRSA isolates (42.1%) carried PVL gene. Of the 11 MLST types, ST59 (44.7%) was the most predominant ST type; t437 (46.1%) was the predominant of the 17 spa types; there were two SCCmec types, most of which were Ⅳ (82.9%). The resistance rates of CA-MRSA to erythromycin and clindamycin were 86.9% and 72.4%, respectively. The resistance rate of PVL-positive strains to gentamicin was higher than that of PVL-negative strains, the difference was statistically significant (53.1% vs. 25.0%, P = 0.012). Four out of five cases of necrotizing pneumonia were PVL positive T910-MRSA-Ⅳa-t318 and one PVL negative ST398-MRSA-V-t034. Conclusion ST59-MRSA-Ⅳa-t437 is the main epidemic clone of CA-MRSA pneumonia in children. No correlation was found between PVL and necrotizing pneumonia. However, the strain ST910-MRSA-Ⅳa-t318 with PVL was associated with necrotizing pneumonia. CA-MRSA pneumonia isolates have high resistance to erythromycin and clindamycin.