福氏志贺菌4c型暴发和散发菌株的脉冲场凝胶电泳分型

PFGE of Shigella flexneri 4c isolates from food-poisoning outbreaks and sporadic diarrhea patients

目的了解杭州地区福氏志贺菌4c 型暴发菌株和散发菌株的分子分型特征。方法对2003和2005年杭州地区的2次食物中毒暴发分离的福氏志贺菌菌株(暴发1和暴发2,菌株数分别为13株和12株)和2005年1例散发腹泻患者分离的福氏志贸菌4c 型离株(1株)进行生化鉴定和血清分型,PCR 检测侵袭性抗原基因 ipaH,改良 Kirby-Bauer 纸片法检测菌株的耐药谱及脉冲场凝胶电泳(pulse fieht gel electrophoresis,PFGE)进行分子分型。结果暴发1中分离的13株菌株均为福氏4c 型,但检测的6株菌株间的 PFGE 图谱存在着相当的差异,Dice 系数为0.78至0.92。暴发2中分离的菌株有10株福氏4c 型和2株福氏 X 型,所有菌株的 PFGE 图谱几乎完全一致。暴发2分离株和暴发1的部分分离株可能存在着一定相关性(Dice 系数大于0.8),而散发菌株与2起暴发的绝大部分菌株间的距离较远(Dice 系数小于0.8)。暴发1、暴发2的分离株和1株散发菌株对14种抗生素的耐药谱略呈差异,暴发2中分离的福氏4c 型和 X 型菌株的耐药谱一致。结论 PFGE 能够很好地辨别福氏志贺菌4c 型的两起暴发菌株和1株散发菌株。福氏志贺菌4c 型菌株具有易变性,可在暴发流行过程中产生 PFGE 图谱的差异、血清亚型的转换、耐药谱的变化等。

Objective To know the molecular characteristic of Shigella flexneri 4c isolates from patients in two foed-poisoning outbreaks and one sporadic diarrhea case in Hangzhou, China. Methods S. flexneri isolates from patients in two food-poisoning outbreaks （ outbreak 1 and outbreak 2, n = 13 and n = 12, respectively） and one sporadic diarrhea patient （ n = 1 ） in Hangzhou during 2003 and 2005 were serotyped. Antibiotic resistances of these isolates were measured by the Kirby-Bauer method, hvasive plasmid antigen gene ipaH was examined by PCR. Pulse field gel electrophoresis （PFGE） was performed for molecular typing. Results In outbreak 1, all 13 isolates were S. flexner/4c, of them 6 isolates tested were quite different in PFGE patterns with dice coefficient from 0. 78 to 0. 92. In outbreak 2, 10 isolates were S. flexner/4c and 2 isolates were S. flexneri X, however their PFGE patterns were almost identical （dice coefficient 〉 0. 8 ）. Compared to the two outbreaks isolates, the sporadic isolate was demonstrated with a distinct PFGE pattern （ dice coefficient 〈 0. 8 ）. The antibiotic resistance patterns with 14 kinds of antibiotics had a little difference among the isolates from outbreak 1, outbreak 2 and sporadic diarrhea patient, but the same pattern was found among 10 isolates of S. flexner/4c and 2 isolates of S. flexner/X from outbreak 2. Conclusions PFGE might distinguish the isolates from these two outbreaks and the sporadic diarrhea patient. Some differences in PFGE patterns, serotypes and antibiotic resistance patterns might occur among S. flexner/4c isolates during an outbreak.