开放性骨折术后迟发性感染患者脓性分泌物分离CA-MRSA菌株分子型与耐药性及毒力特征

Molecular types,drug resistance and virulence characteristics of CA-MRSA strain isolated from purulent secretions of patients with delayed infection after open fracture surgery

目的探究开放性骨折术后迟发性感染患者脓性分泌物分离社区获得性耐甲氧西林金黄色葡萄球菌(CA-MRSA)分子型、耐药性及毒力特征。方法收集2018年1月-2021年7月南京市溧水区人民医院开放性骨折术后患者脓性分泌物分离MRSA 90株,分为CA-MRSA和医院获得性耐甲氧西林金黄色葡萄球菌(HA-MRSA),多位点序列分析(MLST)检测葡萄球菌染色体mec(SCCmec)分型,分析系统检测耐药性,聚合酶链式反应(PCR)检测毒力基因。结果90株MRSA中检出CA-MRSA 53株(58.89%),HA-MRSA 37株(41.11%);53株CA-MRSA对苯唑西林、青霉素、氨苄西林耐药率为100.00%,对米诺环素和磺胺甲噁唑/甲氧苄啶耐药率分别为3.77%和13.21%,而对利奈唑胺、万古霉素、替考拉宁100%敏感,与HA-MRSA比较,CA-MRSA对氯霉素、克林霉素、庆大霉素的耐药率较低(P<0.05);MLST分型中有ST59型33株(62.26%),ST338型7株(13.21%),ST217型4株(7.55%),ST398型、ST5432型各3株(5.66%),ST5424型、ST5型和ST2141型各1株(1.89%);SCCmec分型共检出5种SCCmec分型,CA-MRSA以SCCmecⅣ型和SCCmecⅤ型为主,分别有22株(41.51%)和27株(50.94%),SCCmecⅡ型2株(3.77%),SCCmecⅠ型和SCCmecⅢ型各1株(1.89%);检出7种毒力基因,其中hla、hlb在CA-MRSA和HA-MRSA中均存在,tsst、eta、etb在CA-MRSA和HA-MRSA中检出率均<10%,且37株HA-MRSA中均无etb检出;CA-MRSA中lukSF、PSMα3检出率高于HA-MRSA(P<0.05)。结论开放性骨折术后迟发性感染以CA-MRSA为主,CA-MRSA对多种抗菌药物具有耐药性,但对利奈唑胺、万古霉素、替考拉宁、米诺环素和磺胺甲噁唑/甲氧苄啶敏感性较高,以ST59型、ST338型和SCCmecⅣ、Ⅴ型为主,毒力基因中hla、hlb可能是MRSA重要的毒力基因,而lukSF、PSMα3可能是CA-MRSA和HA-MRSA之间存在差异的关键。

OBJECTIVE To investigate the molecular types,drug resistance and virulence characteristics of community-aquired methicillin-resistant Staphylococcus aureus(CA-MRSA)isolated from purulent secretions from patients with delayed postoperative infection after open fracture.METHODS Totally 9O strains of MRSA isolated from purulent secretions of patients after open fracture surgery were collected in Lishui District People's Hospitalof Nanjing between Jan.2018 and Jul. 2021, and were classified into CA-MRSA and hospital-aquired methicillinresistantStaphylococcus aureus (HA-MRSA). Multi-locus sequence typing (MLST) was used to analyze theStaphylococcal chromosome mec gene cassette (SCCmec) typing, and Vitek-2 Compact automatic microbial analysissystem was applied to detect the drug resistance and PCR was used for virulence genes. RESULTS Among 90strains of MRSA, 53 strains of CA-MRSA (58.89%) and 37 strains of HA-MRSA (41.11%) were detected. 53 strainsof CA-MRSA were 100.00% resistant to 0xacillin, penicillin and ampicillin, 3.77% and 13.21% resistant to minocyclineand compound sulfamethoxazole, respectively, and 1oo% sensitive to linezolid, vancomycin, and teicoplanin. Comparedwith HA-MRSA, CA-MRSA strains had lower resistance rates to chloramphenicol, clindamycin and gentamicin (P<0.05).Among the MLST types, there were 33 strains (62.26%)of ST59 type,7 strains of ST338 type (13.21%), 4strains (7.55%) of ST217 type, 3 strains of ST398 type and ST5432 type (5.66%), 1 strain of ST5424 type, ST5 typeand ST2141(1.89%) each. A total of 5 SCCmec type were detected from SCCmec typing, and CA-MRSA strains weredominated by SCCmec type IV and SCCmec type V, with 22 strains (41.51%) and 27 strains (50.94%), respectively,followed by 2 strains (3.77%) of SCCmecll type, 1 strain (1.89%) each of SCCmecI type and SCCmecIII type. 7 virulencegenes were detected, among which hla and hlb were present in both CA-MRSA and HA-MRSA, and the detectionrates of tsst , eta and etb in CA-MRSA and HA-MRSA were all lower than 10% , and no etb was detected in 37 strains ofHA-MRSA. The detection rates of luk SF and PSMa3 in CA-MRSA were significantly higher than those in HA-MRSA(P<0.05). CONCLUSION CA-MRSA was predominant in delayed postoperative infections after open fracture. CA-MRSAstrains were resistant to a variety of antibacterial drugs, but were highly sensitive to linezolid, vancomycin, teicoplanin,minocycline and compound sulfamethoxazole. ST59 type, ST338 type SCCmecIV and V types were the main types.Among the virulence genes, hla and hlb might be the important virulence genes of MRSA, while lukSF and PSMa3might be the key to the differences between CA-MRSA and HA-MRSA.