Molecular analysis, biofilm formation, and susceptibility of methicillin-resistant Staphylococcus aureus strains causing community- and health care-associated infections in central venous catheters

Abstract INTRODUCTION: The behavior of methicillin-resistant Staphylococcus aureus (MRSA) isolated from central venous catheter-related infection was evaluated to determine its biofilm potential, antimicrobial resistance, and adhesion genes. METHODS: A total of 1,156 central venous catheters (CVC) were evaluated to screen for pathogens. Antimicrobial sensitivity, biofilm formation potential, and molecular analysis of MRSA were examined following standard guidelines. RESULTS: Of the 1,156 samples, 882 (76%) were colonized by bacteria or candida. Among the infected patients, 69% were male and 36% were female with median age of 32 years. Staphylococcus aureus infected 39% (344/882) of CVCs in patients. Of the 59% (208/344) of patients with MRSA, 57% had community acquired MRSA and 43% had hospital acquired MRSA. Linezolid and vancomycin killed 100% of MRSA; resistance levels to fusidic acid, doxycycline, clindamycin, azithromycin, amikacin, trimethoprim-sulfamethoxazole, gentamycin, tobramycin, and ofloxacin were 21%, 42%, 66%, 68%, 72%, 85%, 95%, 97%, and 98% respectively. Strong biofilm was produced by 23% of samples, moderate by 27%, and weak by 50% of MRSA. The presence of adhesion genes, sdrC and sdrD (90%), eno (87%), fnbA (80%), clfA and sdrE (67%), fnbB, sdrD (61%), and cna (51%), in most MRSA samples suggested that the adhesion genes are associated with biofilm synthesis. CONCLUSIONS: The superbug MRSA is a major cause of CVC-related infection. Antibiotic resistance to major classes of antibiotics and biofilm formation potential enhanced superbug MRSA virulence, leading to complicated infection. MRSA causes infection in hospitals, communities, and livestock.摘要：本研究旨在评估分离自中心静脉导管（central venous catheter, CVC）相关感染的耐甲氧西林金黄色葡萄球菌（methicillin-resistant Staphylococcus aureus, MRSA）的生物学特性，明确其生物膜形成潜力、抗菌药物耐药性及黏附基因特征。方法：本研究共纳入1156例中心静脉导管样本进行病原体筛查，依据标准操作指南完成抗菌药物敏感性检测、生物膜形成潜力评估及MRSA的分子生物学分析。结果：1156例样本中，882例（76%）检出细菌或念珠菌定植。感染患者中，男性占69%，女性占36%，中位年龄为32岁。患者的CVC相关感染中，39%（344/882）由金黄色葡萄球菌引起；其中59%（208/344）的患者为MRSA感染，57%为社区获得性MRSA，43%为医院获得性MRSA。利奈唑胺与万古霉素可100%杀灭MRSA；对夫西地酸、多西环素、克林霉素、阿奇霉素、阿米卡星、甲氧苄啶-磺胺甲恶唑、庆大霉素、妥布霉素及氧氟沙星的耐药率分别为21%、42%、66%、68%、72%、85%、95%、97%及98%。23%的MRSA菌株可形成强生物膜，27%形成中等强度生物膜，50%形成弱生物膜。多数MRSA菌株携带黏附基因sdrC与sdrD（90%）、eno（87%）、fnbA（80%）、clfA与sdrE（67%）、fnbB与sdrD（61%）及cna（51%），提示黏附基因与生物膜合成密切相关。结论：超级细菌MRSA是CVC相关感染的主要致病菌。对主要类别抗生素的耐药性及生物膜形成能力增强了MRSA的毒力，导致感染病情复杂化。MRSA可引发医院、社区及家畜相关感染。