Liu Ying-chao, Geng Wen-jing, Wu De-jing, Li Xiang-mei, Wang Chuan-qing, Lu Quan, Deng Qiu-lian, Zheng Yue-jie, Liu Lan, Li Chang-chong, Shang Yun-xiao, Zhao Chang-an, Yang Yong-hong, Shen Xu-zhuang
Capital Medical University, Beijing, China.
Zhonghua Er Ke Za Zhi. 2012 Jan;50(1):38-44.
To investigate the molecular characteristics of methicillin-resistant Staphylococcus aureus (MRSA) isolates from Chinese children in seven cities.
A total of 134 MRSA isolates were collected from nine hospitals. Multilocus sequence typing and spa typing were analyzed by polymerase chain reaction (PCR), and staphylococcal chromosomal cassette mec (SCCmec) type was analyzed by multiplex PCR. The Panton-Valentine leukocidin (pvl) gene was also detected.
Most MRSA strains were isolated from pneumonia and skin and soft tissue infection (SSTIs) patients, accounting for 82.1%. Overall, 16 sequence types (STs) were obtained, and CC59 (51.7%) was found to be the most prevalent, which included ST 59 and ST 338, followed by ST239 (16.4%). SCCmec types II, III, IV, and V were also identified in the current study. SCCmec type IV was the most predominant type at 50.0%, followed by SCCmec type V at 23.9% and III at 23.9%. SCCmec subtypes IVa, IVc, and IVg were found among SCCmec type IV strains, whereas IVa was the main subtype at 77.6%. Twenty-six spa types were also identified, among which the predominant type was t437 (47.8%). The prevalence of pvl genes and the SCCmec type of strain was relevant, and the pvl gene positive rate was higher in SCCmec type IV and V-type strains than in SCCmec type II and III strains (58.6% vs. 14.3%, P < 0.05); there was a significant difference between them. In the strains isolated from pneumonia and SSTIs, ST59-MRSA-IVa(t437) was the predominant clone. There were five clones detected from the strains isolated from septicemia, with ST59-MRSA-IVa(t437) and ST59-MRSA-V(t437) as the main clones (57.1%). Various predominant clones existed in different regions. ST59-MRSA-IVa(t437) was the prevalent clone in the Guangzhou, Beijing, Chongqing, and Shenzhen areas, whereas ST239-MRSA-III(t037) was the prevalent clone in the Shanghai area. Fifty percent of the isolates from the Wenzhou area belonged to ST910-MRSA-V(t318), whereas three clinical strains isolated from the Shenyang region belonged to three different types.
The results indicate that MRSA isolates from Chinese children are largely associated with the ST59-MRSA-IV(t437) and ST239-MRSA-III(t037) clones. These two may belong to community-acquired MRSA and hospital-acquired ones, respectively. Different prevalent clones were detected in different diseases and different regions. Therefore, there is a need to conduct further research on clinical isolates, which can guide the choice of antibiotic treatment and the examination of MRSA prevalence.
调查来自中国七个城市儿童的耐甲氧西林金黄色葡萄球菌（MRSA）分离株的分子特征。
从九家医院共收集134株MRSA分离株。通过聚合酶链反应（PCR）分析多位点序列分型和spa分型，通过多重PCR分析葡萄球菌染色体盒式mec（SCCmec）类型。同时检测杀白细胞素（pvl）基因。
大多数MRSA菌株分离自肺炎及皮肤和软组织感染（SSTIs）患者，占82.1%。总体上，共获得16种序列类型（STs），其中CC59（51.7%）最为常见，包括ST59和ST338，其次是ST239（16.4%）。本研究中还鉴定出SCCmec II、III、IV和V型。SCCmec IV型最为主要，占50.0%，其次是SCCmec V型，占23.9%，III型占23.9%。在SCCmec IV型菌株中发现了IVa、IVc和IVg亚型，其中IVa是主要亚型，占77.6%。还鉴定出26种spa类型，其中主要类型为t437（47.8%）。pvl基因的流行率与菌株的SCCmec类型相关，SCCmec IV型和V型菌株的pvl基因阳性率高于SCCmec II型和III型菌株（58.6%对14.3%，P<0.05）；两者之间存在显著差异。在从肺炎和SSTIs分离的菌株中，ST59-MRSA-IVa(t437)是主要克隆。从败血症分离的菌株中检测到五个克隆，以ST59-MRSA-IVa(t437)和ST59-MRSA-V(t437)为主要克隆（57.1%）。不同地区存在各种主要克隆。ST59-MRSA-IVa(t437)是广州、北京、重庆和深圳地区的流行克隆，而ST239-MRSA-III(t037)是上海地区的流行克隆。温州地区50%的分离株属于ST910-MRSA-V(t318)，而从沈阳地区分离的三株临床菌株属于三种不同类型。
结果表明，中国儿童的MRSA分离株在很大程度上与ST59-MRSA-IV(t437)和ST239-MRSA-III(t037)克隆相关。这两者可能分别属于社区获得性MRSA和医院获得性MRSA。在不同疾病和不同地区检测到不同的流行克隆。因此，有必要对临床分离株进行进一步研究，这可以指导抗生素治疗的选择和MRSA流行情况的检查。
