Department of Nephrology and Rheumatology, Haikou People's Hospital Affiliated to Xiangya School of Medicine, Haikou, China.
Department of Orthopedics, Peking University Third Hospital, No. 49 North Garden Road, Haidian District, Beijing, China.
BMC Microbiol. 2023 Sep 23;23(1):267. doi: 10.1186/s12866-023-03017-2.
Peritonitis is the most important complication of peritoneal dialysis (PD) and coagulase-negative staphylococci (CNS) are a frequent cause of dialysis-related infections. The association between SCCmec typing with psm-mec positivity in staphylococci and PD-related infections has not been identified. We aim to investigate the molecular epidemiology of CNS isolated from PD-peritonitis in a single Chinese center, focusing on the genetic determinants conferring methicillin resistance.
We collected 10 genetically unrelated CNS isolates from 10 patients with CNS PD-related peritonitis. The patients were divided into two groups based on the results of MIC to oxacillin: the methicillin-resistant CNS (MRCNS) and methicillin-sensitive CNS (MSCNS) groups. The biofilm formation group (BFG) and the non-biofilm formation group (NBFG) were used as the control groups. Phenotypic and molecular methods were used to analyze SCCmec types I, II and III, associated genes and biofilm formation and the existence of psm-mec. The demographic data and clinical indicators were collected.
Ten CNS PD-related peritonitis patients were enrolled for this study. There were 6 MRCNS and 4 MRCNS isolates. SCCmec types were fully determined in 10 isolates. Seven staphylococci (70%) carried SCCmec, of which 4 isolates carried single SCCmec type I (40%) and 3 isolates had multiple SCCmec elements (I + III). Of the 6 MRCNS isolates, 3 carried SCCmec type I (50%) and 2 isolates carried SCCmec type I + III (33.3%). A high diversity of ccr types, mec complexes and ccr-mec complex combinations was identified among the 10 CNS isolates. The psm-mec gene was detected in 2/10 (20%) CNS isolates. There was no mutation in the psm-mec gene.
The majority of isolates were hospital-associated isolates. Furthermore, 2 psm-mec positive isolates were MRCNS in the NBFG. The PD patients frequent exposure to hospital would be the main risk factor. The presence of the psm-mec signal in the spectra of the MRCNS tested here demonstrates the presence of certain SCCmec cassettes that convey methicillin resistance.
腹膜炎是腹膜透析（PD）最严重的并发症，凝固酶阴性葡萄球菌（CNS）是透析相关感染的常见原因。尚未确定葡萄球菌中 SCCmec 分型与 psm-mec 阳性之间与 PD 相关感染的关系。我们旨在研究单个中国中心 PD 相关性腹膜炎分离的 CNS 的分子流行病学，重点是赋予耐甲氧西林的遗传决定因素。
我们从 10 名 CNS PD 相关性腹膜炎患者中收集了 10 个遗传上无关的 CNS 分离株。根据 MIC 对苯唑西林的结果将患者分为两组：耐甲氧西林 CNS（MRCNS）和甲氧西林敏感 CNS（MSCNS）组。将生物膜形成组（BFG）和非生物膜形成组（NBFG）作为对照组。使用表型和分子方法分析 SCCmec 类型 I、II 和 III、相关基因和生物膜形成以及 psm-mec 的存在。收集人口统计学数据和临床指标。
本研究共纳入 10 例 CNS PD 相关性腹膜炎患者。有 6 例 MRCNS 和 4 例 MRCNS 分离株。10 株均完全确定 SCCmec 类型。7 株葡萄球菌（70%）携带 SCCmec，其中 4 株携带单一 SCCmec 型 I（40%），3 株携带多种 SCCmec 元件（I+III）。6 株 MRCNS 分离株中，3 株携带 SCCmec 型 I（50%），2 株携带 SCCmec 型 I+III（33.3%）。10 株 CNS 分离株中存在 ccr 类型、mec 复合物和 ccr-mec 复合物组合的高度多样性。在 10 株 CNS 分离株中检测到 2 株（20%）携带 psm-mec 基因。psm-mec 基因无突变。
大多数分离株为医院定植株。此外，NBFG 中 2 株 psm-mec 阳性分离株为 MRCNS。PD 患者频繁接触医院可能是主要危险因素。这里检测到的 MRCNS 中 psm-mec 信号的存在表明存在某些赋予耐甲氧西林的 SCCmec 盒。
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