Methicillin-resistant Staphylococcus aureus (MRSA) strains are prevalent in healthcare services. Medical students are at risk for MRSA carriage, subsequent infection and potential transmission of nosocomial infection.Few studies have examined MRSA carriage among medical students. In this prospective cohort study, between July 2016 and June 2017, two nasal swab samples were taken per student 4 weeks apart during their pediatric internship. MRSA typing was performed by staphylococcal cassette chromosome mec (SCCmec) types, Panton Valentine leukocidin (PVL) encoding genes. A total of 239 sixth year medical students, 164 (68.6%) male (M/F:2.1),with median age 25 years (min–max; 23–65 years) were included in this prospective cohort study. Among 239 students, 17 students (7.1%) were found to be colonized with methicillin-sensitive S. aureus (MSSA) at the beginning of pediatric internship. After 4 weeks, at the end of pediatric internship totally 52 students were found to be S. aureus colonized (21.8%). Three of 52 S. aureus isolates were MRSA (1.3%) and the rest was MSSA (20.5%), all were PVL gen negative. Two of three MRSA isolates were characterized as SCCmec type IV, one isolate was untypeable SCCmec. Nasal carriage of S. aureus increased from 7.1% to 21.5% (p < 0.001). Nasal S. aures colonization ratio was higher in students working in pediatric infectious disease service (p = 0.046). Smoking was found to be associated with a 2.37-fold [95% CI (1.12–5.00); p = 0.023] and number of patients in pediatric services was 2.66-fold [95% CI (1.13–6.27); p = 0.024] increase the risk of nasal S. aureus colonization. Gender was not found to increase risk of MRSA carriage. MSSA nasal carriage increased at the end of pediatric internship and significantly high in students working in pediatric infectious diseases services. Smoking and high number of patients in pediatric services significantly increase S.aureus colonization.

中文翻译：

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六年级医学生在儿科服务实践中鼻样本分离的金黄色葡萄球菌菌株的分子特征

耐甲氧西林金黄色葡萄球菌 (MRSA) 菌株在医疗保健服务中很普遍。医学生有 MRSA 携带、随后感染和院内感染的潜在传播的风险。很少有研究调查医学生中 MRSA 携带的情况。在这项前瞻性队列研究中，2016 年 7 月至 2017 年 6 月期间，每个学生在儿科实习期间相隔 4 周采集了两个鼻拭子样本。MRSA 分型由葡萄球菌盒染色体 mec (SCCmec) 类型、Panton Valentine 杀白细胞素 (PVL) 编码基因进行。共有 239 名六年级医学生，164 名（68.6%）男性（男/女：2.1），中位年龄 25 岁（最小-最大；23-65 岁）被纳入这项前瞻性队列研究。在 239 名学生中，17 名学生 (7.1%) 被发现定植了甲氧西林敏感链球菌。儿科实习初期的金黄色葡萄球菌 (MSSA)。4 周后，在儿科实习结束时，共有 52 名学生被发现定植了金黄色葡萄球菌 (21.8%)。52 株金黄色葡萄球菌分离株中有 3 株为 MRSA (1.3%)，其余为 MSSA (20.5%)，均为 PVL 基因阴性。三个 MRSA 分离物中的两个被表征为 SCCmec IV 型，一个分离物是不可分型的 SCCmec。金黄色葡萄球菌的鼻腔携带率从 7.1% 增加到 21.5% (p < 0.001)。在儿科传染病服务部门工作的学生中，鼻金黄色葡萄球菌定植率较高（p = 0.046）。发现吸烟与 2.37 倍 [95% CI (1.12–5.00); p = 0.023]，儿科服务的患者数量是 2.66 倍 [95% CI (1.13–6.27)；p = 0.024] 增加鼻部金黄色葡萄球菌定植的风险。未发现性别会增加 MRSA 携带的风险。在儿科实习结束时，MSSA 鼻腔携带量增加，并且在儿科传染病服务工作的学生中显着增加。儿科服务中吸烟和大量患者显着增加了金黄色葡萄球菌的定植。