北京地区宋内志贺菌分子流行病学特征分析

目的 了解北京地区宋内志贺菌毒力基因分布及分子流行病学特征. 方法 采用实时荧光PCR方法检测毒力基因、脉冲场凝胶电泳(PFGE)分型,多位点序列分型(MLST)及多位点可变数目串联重复序列分析(MLVA)等方法对北京地区2001～2009年50株志贺菌菌株进行分子流行病学特征分析. 结果 50株菌中,ipaH、set1、sen三种毒力基因的携带率分别为98％,18％和78％.选取19株流行病学和遗传背景无关的菌株,进行MLST、MLVA与PFGE分型方法的比较,MLST为1个序列型ST152 complex:adk(11)、fumC (63)、gyrB(7)、icd(1)、mdh(14)、purA (7)、recA(7); MLVA被分成15个型别,D值为0.9708;PFGE分成12个型别,D值为0.9532.MLVA初筛得到的8个可变数目串联重复(VNTR)位点用于扩大菌株分析,发现50株志贺菌被分为21个MLVA的型别,TS002和TS001为主要型别. 结论 北京地区近年来流行的宋内志贺菌存在毒力基因的丢失,MLVA分子型别复杂,存在多克隆来源,提示需要进行连续系统的分子流行病学监测.

Molecular epidemiological characteristics of Shigella Sonnei isolates in Beijing

Objective To understand the distribution and epidemiological characteristics of Shigella Sonnei isolates in Beijing. Methods Fifty Shigella Sonnei strains isolated during 2001-2009 were etected for ipaH,setl and sen virulence gene by realtime PCR and molecular typed by pulsed-field gel electrophoresis （PFGE）,multilocus sequence subtyping（MisT）and multilocus variable-number tandem-repeat analysis（MLVA）. Results The distribution of ipaH, setl and sen virulence gene among 50 strains were 98%,18%和78%,respectively. Nineteen unrelated strains were selected for comparison of molecular typing methods of PFGE,MIST and MLVA. MIST results produced just one sequence type ST152 complex： adk（11 ）,fumC（63）,gyrB（7）,icd（ 1 ）,mdh（14） ,purA（7） and recA（7） ;MLVA produced 15 types with a D value of 0.9708,while PFGE for 12 types with a D value of 0.9532. Through screening 8VNTR loci,50 Shigella Sonnei isolates were classified into 21 MLVA types with a D value of 0.9708,while 130 Shigellaflexneria strains were classified into 63 MLVA types by PFGE,with 2 dominant types TS002 and TS001. Conclusions The loss of virulence genes,genetic polymorphism and multiple clones source occur to ShigeUa Sonnei isolates in Beijing in recent years,suggesting a continuous and systematic molecular epidemiological surveillance is neccessary.