金黄色葡萄球菌感染住院患儿鼻部携带菌株的研究

Epidemiological study on nasal carriage in hospitalized children infected with Staphylococcus aureus

摘要:

目的 观察金黄色葡萄球菌(简称金葡菌)感染的住院患儿鼻部携带菌株与金葡菌感染之间的相关关系。方法 以56 例金葡菌感染的住院患儿为研究对象,采集鼻拭子标本进行培养,检测患儿的金葡菌鼻部携带率,并采用PCR 方法分别检测临床菌株和鼻部携带菌株的mecA 耐药基因和PVL 毒力基因。结果 56例金葡菌感染患儿中,22 例(39%)鼻部携带金葡菌,携带患儿以婴儿为主(18 例)。50%(11/22)携带患儿既往1 年内有住院史。在感染株中,耐甲氧西林金葡菌(MRSA)占29%(16/56);在携带株中,MRSA 占32%(7/22)。PCR 检测携带患儿的临床感染菌株和鼻部携带菌株mecA 阳性结果完全一致,可一一对应;90%(4/5)的PVL 阳性鼻部携带菌株可以与临床感染菌株一一对应,且均为MRSA 菌株。结论 鼻部定植是金葡菌感染的潜在危险因素。医院内传播可能是导致金葡菌鼻部携带,最终导致其感染的重要潜在危险。金葡菌鼻部携带菌株与感染菌株可能具有同源关系,需要进一步通过多位点序列分型明确其同源关系。

Abstract:

Objective To study the relationship between nasal carriage and Staphylococcus aureus (S. aureus) infection in hospitalized children. Methods Fifty-six hospitalized children infected with S. aureus were recruited in this study. Nasal swabs were collected and cultured, and the nasal carriage rate of S. aureus was examined. PVL virulence gene and mecA resistance gene were both detected in clinical strains and nasal carriage strains by PCR. Results Twenty-two (39%) of the 56 children had nasal carriage of S. aureus, and most of them (18 cases) were younger than one year. Among these 22 children, 11 (50%) had previous hospitalization over the past year. In the infected strains, the rate of methicillin-resistant S. aureus (MRSA) was 29% (16/56), while it was 32% (7/22) in carriage strains. The mecA positive results in clinical strains were consistent with the results in nasal carriage strains. Among 5 PVL-positive nasal carriage strains, 4 (90%) could be matched with their clinical strains, all of which were MRSA. Conclusions Nasal carriage is a potential risk factor for S. aureus infection. Nosocomial transmission may lead to nasal carriage, which can cause S. aureus infection. The isolation rate of MRSA is high in hospitalized children infected with S. aureus, which implies that more attention is needed for this situation. The isolates from noses may be clonally identical to the isolates from clinical secretions, and the homology between them needs to be confirmed by multi-locus sequence typing.