Increasing clinical impact and microbiological difficulties in diagnosing coagulase-negative staphylococci in infective endocarditis- a review starting from a series of cases

Coagulase-negative staphylococci (CoNS) are an emergent aetiology of infective endocarditis (IE) on native valves in previously healthy individuals, its presence being associated with prosthetic valves or with other cardiac implants. The identification of CoNS in cultures was customarily seen as contamination, but more recent epidemiological studies have revealed an increasing number of causative and virulent new CoNS species. Starting from two clinical cases of community-acquired CoNS IE on native valves, the review debates the difficulties in identifying CoNS as the causal pathogens, comprising differentiation of contamination from infection in IE, alongside the challenges raised by antibiotic resistance. Even if the risk of CoNS IE is more increased in subjects with prosthetic materials or other foreign devices and immunodeficiencies, native valve infections with these staphylococci are increasing and should be considered important pathogens in IE. Despite the lack of sensitive and specific tools to correctly differentiate contamination from infection in CoNS endocarditis, a comprehensive evaluation with clinical and paraclinical data accurately succeeds in establishing the diagnosis. The genetic profile of CoNS predisposes to antibiotic multi-resistance, making the treatment of IE challenging; the rapid identification of antibiotic susceptibility is essential to prescribe the appropriate therapy and improve outcomes.

凝固酶阴性葡萄球菌（Coagulase-negative staphylococci, CoNS）是既往健康人群自体瓣膜感染性心内膜炎（infective endocarditis, IE）的新兴病因，其发生与人工瓣膜或其他心脏植入物密切相关。既往临床实践中，培养检出的CoNS通常被视作污染菌，但近年来的流行病学研究显示，具有致病性与毒力的新型CoNS菌种数量呈上升趋势。本综述以2例社区获得性自体瓣膜CoNS感染性心内膜炎临床病例为切入点，探讨了将CoNS鉴定为致病病原体所面临的多重困境：既要区分感染性心内膜炎中污染与感染的差异，又需应对抗生素耐药性带来的挑战。尽管佩戴人工材料或其他异物装置、存在免疫功能缺陷的人群罹患CoNS感染性心内膜炎的风险显著升高，但此类葡萄球菌引发的自体瓣膜感染病例正不断增加，因此应将其视为感染性心内膜炎的重要致病菌。尽管目前尚缺乏能够精准区分CoNS心内膜炎中污染与感染的敏感且特异的检测手段，但结合临床与辅助检查数据开展全面评估，即可准确完成诊断。CoNS的遗传特性使其易于获得多重耐药性，这使得感染性心内膜炎的治疗极具挑战性；快速鉴定抗生素敏感性对于制定合理治疗方案、改善患者预后具有至关重要的意义。