食品和临床来源耐甲氧西林金黄色葡萄球菌分离株表型及分子特征研究

Phenotypic and molecular characteristics of methicillin-resistant Staphylococcus aureus isolated from food and clinical samples

中文关键词:  耐甲氧西林金黄色葡萄球菌  耐药性  生物膜  分子特征  进化分析

英文关键词:methicillin-resistant Staphylococcus aureus  drug resistance  biofilm  molecular characteristics  evolutionary analysis

中文摘要:

      目的 研究耐甲氧西林金黄色葡萄球菌(methicillin-resistant Staphylococcus aureus, MRSA)食品和临床样本分离株的耐药性、菌膜形成能力及分子特征。方法 对2019—2020年陕西地区市售食品中分离的21株MRSA和某三甲医院临床感染病例中分离的30株MRSA进行药物药敏性试验, 多位点序列分型(multilocus sequence typing, MLST)、葡萄球菌蛋白A (Staphylococcal protein A, spa)分型、葡萄球菌染色体盒mec (Staphylococcal cassette chromosome mec, SCCmec)分型, 生物膜形成能力测定; 通过全基因组测序基于单核苷酸多态性(single nucleotide-polymorphism, SNP)对不同来源菌株进行系统进化分析。结果 51株食品和临床分离的MRSA菌株对青霉素、苯唑西林、红霉素、克林霉素、四环素等抗菌药物耐药率均超过50%, 其中青霉素、苯唑西林的耐药率最高, 为100%, 其余依次为红霉素、克林霉素、四环素, 耐药率分别为98.04%、96.08%、52.94%。21株食品和30株临床分离MRSA菌株分子型别均以ST59-t437-IVa(2B)型为主, 分别占比为52.38% (11/21)和36.67% (11/30)。21株食品分离MRSA菌株中38.09% (8/21)具有生物膜形成能力, 30株临床分离MRSA菌株100.00%具有生物膜形成能力。种系进化树分析结果显示ST59-t437-IVa(2B)型为食品和临床分离MRSA主要进化分支, 且两种来源菌株部分位于同一进化分支。结论 本研究中食品和临床分离MRSA菌株耐药种类及其耐药率呈现高度一致; 临床较食品分离MRSA菌株生物膜形成能力强; 食品和临床分离的MRSA中一部分菌株具有较近的亲缘关系, 提示食源性MRSA风险不容忽视, 值得进一步研究与关注。

英文摘要:

      Objective To investigate the drug resistance, biofilm formation ability, and molecular characteristics of methicillin-resistant Staphylococcus aureus (MRSA) isolated from food and clinical samples. Methods A total of 21 MRSA strains isolated from commercial food and 30 MRSA strains isolated from clinical cases in a Class 3 Grade A hospital in Shaanxi from 2019 to 2020 were tested for drug susceptibility, MLST, spa, SCCmec typing, and biofilm formation ability. The phylogenetic analysis of strains from different sources was performed based on SNP by whole genome sequencing. Results The resistance rates of 51 MRSA strains to penicillin, oxacillin, erythromycin, clindamycin, tetracycline, and other antibiotics exceeded 50%. Penicillin and oxacillin exhibited the highest resistance rates (100%), followed by erythromycin, clindamycin, and tetracycline with resistance rates of 98.04%, 96.08%, and 52.94% respectively. The ST59-t437-IVa(2B) molecular type was predominant among 21 food MRSA strains and 30 clinical MRSA strains, accounting for 52.38% (11/21) and 36.67% (11/30), respectively. Among the 21 food-borne MRSA strains, 38.09% (8/21) exhibited the capacity for biofilm formation, while all 30 clinical MRSA strains demonstrated biofilm-forming ability. The phylogenetic analysis revealed that ST59-t437-IVa(2B) constituted the primary evolutionary lineage of MRSA strains isolated from both food and clinical samples, with some strains from these two sources falling within the same evolutionary branch. Conclusion The drug-resistant types and rates of drug resistance in MRSA strains isolated from both food and clinical sources exhibited a high degree of consistency in this study. Moreover, the biofilm formation ability was found to be stronger in clinical MRSA isolates compared to those derived from food-borne sources. Additionally, close genetic relationships were observed between certain MRSA strains obtained from both food and clinical samples, highlighting the significance of further research and attention towards the risk posed by food-borne MRSA.