北京地区2011－2014年致儿童猩红热A组链球菌emm基因型别变化特征分析

目的 了解北京地区致儿童猩红热A组链球菌(GAS)emm基因型别分布,并探讨其型别变化与猩红热病例的关系。方法 收集2011－2014年5－7月北京市36家医院临床诊断为猩红热病例咽拭子GAS分离菌株,采用PCR联合测序方法对分离菌株进行emm分型,选取中国疾病监测信息报告管理系统中北京市猩红热病例报告数据进行分析。结果 共采集咽拭子标本2 161份,分离GAS菌株762株,阳性率为35.3%(762/2 161)。检测到7个emm型别,其中emm12型占69.4%(529/762),emm1型占29.8%(227/762),其他5种emm型别(11、22、75、89、128)占0.8%(6/762)。分析各年份emm型别构成比:2011年emm12型82.2%(295/359),emm1型16.7%(60/359),其他型(11、22、89)1.1%(4/359);2012年emm12型77.3%(123/163),emm1型23.9%(39/163),emm75型0.6%(1/163);2013年emm12型50.7%(38/75),emm1型49.3%(37/75);2014年emm12型44.2%(73/165),emm1型55.2%(91/165),emm128型0.6%(1/165)。不同年份emm型别构成比变化的差异有统计学意义(P<0.001)。2011、2012年emm12为主导菌型,2014年主导型别转换为emm1型。2011－2014年报告猩红热病例分别为6 152、2 908、2 048和3 918例,以2011年报告例数最多,2014年比2013年报告病例数增加91.31%。2011年GAS分离株emm型别存在年龄差异,其中1～5岁组分离的emm12型高于>5岁组(P<0.05)。2011、2013年分离GAS菌株存在地区差异,2011年emm1型分离株为城区高于郊区(P<0.05),2013年emm1型为郊区高于城区(P<0.05)。结论 2011－2014年北京地区GAS菌株优势菌型为emm12和emm1型;不同年份emm12、emm1变换成为主导菌型;emm主导菌型变化与猩红热病例变化趋势有关。

emm types of mutation in scarlet-fever-related group A streptococcal, among children in Beijing, 2011-2014

Objective To understand the distribution of emm gene types related to group A streptococcus-caused scarlet fever among children in Beijing and to analyze the relationship between the mutation of the emm types and scarlet fever. Methods Nasopharyngeal swab samples were collected from the scarlet fever cases diagnosed in 36 hospitals in Beijing to isolate the GAS strains from May to July, betgween 2011 and 2014. Genotyping of emm gene was performed with PCR and N-terminal gene fragments of M protein were sequenced. Data of all the scarlet fever cases in Beijing that reported through the National Notifiable Infectious Disease Surveillance System(NNIDSS), were gathered and analyzed. Results Among the collected 2 161 nasopharyngeal swabs, 762 GAS strains were identified (35.3%). In addition, 7 emm types were detected, in which emm12 accounted for 69.4%(529/762), emm1 accounted for 29.8% (227/762), and other five types (emm 11, 22, 75, 89,and 128) accounted for 0.8% (6/762), respctively. Compared with the emm types detected between 2011 and 2014, emm12, emm1 and other types accounted for 82.2% (295/359), 16.7% (60/359) and 1.1%(4/359, including emm11, 22 and 89) in 2011 respectively. emm12, emm1 and emm75 accounted for 77.3% (123/163), 23.9% (39/163) and 0.6% (1/163) respectively in 2012. emm12 and emm1 accounted for 50.7% (38/75) and 49.3% (37/75) in 2013 while emm12, emm1 and emm128 accounted for 44.2% (73/165), 55.2% (91/165) and 0.6% (1/165) respectively in 2014. The differences of the constitution of emm types from 2011 to 2014 appeared statistically significant (P<0.001). In 2011 and 2012, major type appeared as emm12, but in 2014, emm1 became predominant. A total of 6 152 cases were reported in 2011, while 2 908, 2 048 and 3 918 cases were reported in 2012, 2013 and 2014 respectively. Age specific differences were noticed in the distribution of emm types GAS strains in 2011, with the number of emm12 strains detected higher in 1-5 year olds than in age group >5 years (P<0.05). There were area specific differences in distribution of emm types of GAS strains seen in 2011 and 2013. In 2011, the number of emm1 strains detected in urban area was higher than in suburb area (P<0.05). However, in 2013, the number of emm1 strains detected in suburb area was seen higher than in urban area (P<0.05). Conclusion GAS with emm12 and GAS emm1 appeared interchangeably predominant in Beijing from 2011 to 2014. Changes in predominant emm types seemed also related to the trends of incidence rates on scarlet fever.