Differences in resistance profiles and virulence genes among methicillin-resistant and methicillin-susceptible Staphylococcus aureus of different lineages at a public tertiary hospital

Abstract INTRODUCTION Staphylococcus aureus is a major nosocomial pathogen that is associated with high virulence and the rapid development of drug resistance. METHODS We analyzed and compared the antimicrobial resistance, virulence profiles, and molecular epidemiology of 67 S. aureus strains, including 36 methicillin-sensitive (MSSA) and 31 methicillin-resistant (MRSA) strains recovered from a public hospital located in south-eastern Brazil. RESULTS The clones circulating in this hospital presented a great diversity, and the majority of the strains were related to clones responsible for causing worldwide epidemics: these included USA100 (New York/Japan clone), USA300, and USA600. The 31 MRSA (22 SCCmecII and 9 SCCmecIV) and 36 MSSA strains exhibited low resistance against gentamicin and trimethoprim/sulfamethoxazole. No MRSA strain showed resistance to tetracycline. Virulence gene carriage was more diverse and abundant in MSSA than in MRSA. Of the evaluated adhesion-related genes, ebpS was the most prevalent in both MSSA and MRSA strains. The genes bbp and cna showed a strong association with MSSA strains. CONCLUSIONS Our findings reinforce the idea that MSSA and MRSA strains should be carefully monitored, owing to their high pathogenic potential.

摘要 研究背景：金黄色葡萄球菌（Staphylococcus aureus）是一类主要的医院感染病原菌，兼具高致病性与快速产生耐药性的特征。方法：本研究对67株金黄色葡萄球菌菌株的抗菌耐药性、毒力谱及分子流行病学特征进行了分析与比较，其中包含36株甲氧西林敏感金黄色葡萄球菌（MSSA）与31株甲氧西林耐药金黄色葡萄球菌（MRSA），上述菌株均分离自巴西东南部一所公立医院。结果：该医院流行的克隆菌株具有高度多样性，且多数菌株与引发全球流行的克隆株相关，包括USA100（纽约/日本克隆株）、USA300及USA600。本次研究的31株MRSA菌株（其中22株携带SCCmecⅡ型、9株携带SCCmecⅣ型）与36株MSSA菌株，对庆大霉素与甲氧苄啶/磺胺甲恶唑均表现出较低的耐药性；未发现任何MRSA菌株对四环素耐药。MSSA菌株携带的毒力基因种类更丰富、丰度更高。在评估的黏附相关基因中，ebpS在MSSA与MRSA菌株中均最为普遍；bbp与cna基因与MSSA菌株呈现显著相关性。结论：本研究结果进一步证实，鉴于MSSA与MRSA菌株均具有较高的致病潜力，需对二者开展严格的监测工作。