引起皮肤软组织感染的杀白细胞素阳性社区获得性耐甲氧西林金黄色葡萄球菌分子特征研究

目的 了解分离自临床皮肤和软组织感染(SSTIs)患者携带杀白细胞素基因(pvl)社区获得性耐甲氧西林金黄色葡萄球菌(pvl⁺-CA-MRSA)的分子特征。方法 从SSTIs患者中分离出92株CA-MRSA。采用聚合酶链反应(PCR)和测序检测pvl基因及其突变。pvl⁺-CA-MRSA菌株进行序列类型(STs)与克隆复合物(CCs)、葡萄球菌盒式染色体mec(SCCmec)、葡萄球菌蛋白基因(spa)多态性、辅助基因调控子(agr)位点、脉冲场凝胶电泳(PFGE)分型和多位点序列分型(MLST)。采用VITEK-2 Compact全自动微生物鉴定系统进行CA-MRSA药物敏感试验。结果 92株CA-MRSA中，24株(26.1%)为pvl⁺-CA-MRSA,其中91.7%(22/24)为pvl的H亚型，68株(73.9%)为未携带pvl基因CA-MRSA(pvl^--CA-MRSA)。24株pvl⁺-CA-MRSA中，共有8种STs和7种CCs,其中以ST59(62.5%,15...

Molecular characteristics of Panton-Valentine leukocidin-positive community-acquired methicillin-resistant Staphylococcus aureus isolates causing skin and soft tissue infections

The aim of this study was to determine the molecular characteristics of Panton-Valentine leukocidin-positive (pvl⁺) community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) isolates from patients with skin and soft tissue infections (SSTIs). A total of 92 CA-MRSA strains were isolated from patients with SSTIs. In all isolates, the presence of pvl genes was detected, and mutation of pvl gene sequences was analyzed with polymerase chain reaction and sequencing. The pvl⁺-CA-MRSA isolates were analyzed to determine sequence types (STs), clone complexes (CCs), staphylococcal cassette chromosome mec (SCCmec) type, staphylococcal protein A (spa) gene polymorphism type, pulsed-field gel electrophoresis type, accessory gene regulator (agr) locus type and multi locus sequence type. A VITEK-2 Compact auto-microorganism identification system was used for drug susceptibility tests of all CA-MRSA isolates. Of the 92 CA-MRSA isolates, 24 (26.1%) were pvl⁺; 91.7% of the pvl⁺ isolates (22/24) belonged to the H variant of pvl (pvlH). Among the 24 pvl⁺-CA-MRSA isolates, eight STs and seven CCs had predominance of ST59 (62.5%,15/24) and CC59 (70.8%,17/24). In the pvl⁺-CA-MRSA isolates, SCCmec III and IVa accounted for 54.2% and 33.3%, respectively; agr I (87.5%, 21/24) was the most common agr allele, and the remainder were agr III. Eight spa types were detected in the pvl⁺-CA-MRSA isolates; the most common spa type was t437 (66.7%, 16/24). The pvl⁺-CA-MRSA isolates showed higher resistance rates to erythromycin, clindamycin and tetracycline (>50%), but lower resistance rates to sulfamethoxazole/trimethoprim, ciprofloxacin and gentamicin (8.3%-16.7%), No vancomycin, rifampicin, moxifloxacin and linezolid resistant pvl⁺-CA-MRSA isolates were found. Except for a lower resistance rate to tetracycline (P<0.05), no significant differences were observed in resistance rates to the other tested antibiotics between pvl^--CA-MRSA and pvl⁺-CA-MRSA. All results indicated that the CA-MRSA isolates causing SSTIs had a high positivity rate of pvl-encoding genes, and pvlH2, ST59/CC59, SCCmec III/Iva, agrI and t437 were the dominant clones of CA-MRSA isolates.