上海市浦东新区食源性小肠结肠炎耶尔森菌耐药及分子流行病学特征

目的 了解上海市浦东新区食源性小肠结肠炎耶尔森菌耐药及分子流行病学特征。方法 2012-2016年主动、定点采集上海市浦东新区4类流通生鲜食品，使用冷增菌方法分离小肠结肠炎耶尔森菌，并分析菌株生物型、血清型、毒力基因型、耐药性和PFGE分子型别。结果 共采集食品3 900份（禽类590份、畜类1 074份、水产品1 488份、蔬菜748份），其中111份（2.8%）检出小肠结肠炎耶尔森菌。禽类制品（5.3%，31/590）和畜类制品（4.5%，48/1 074）的检出率高于水产品（1.6%，24/1 488）和蔬菜制品（1.1%，8/748）。分离株以生物1A型（95.5%）和O：8血清型（42.3%）为主，且分离数与年总分离数呈正相关。所有菌株均缺失4种（ail、ystA、yadA和virF）产毒株标记的毒力基因，76株（68.5%）ystB基因阳性（其中35株属于1A/O：8/ystB）。分离株对氨苄西林（74.8%）和阿莫西林/克拉维酸（70.3%）的耐药率最高，对头孢西丁不敏感率超过50.0%；未发现三代头孢菌素或氟喹诺酮类抗菌药物耐药株，38.7%（43/111）的菌株为多重耐药。O：8和O：5血清型菌株分别存在44和18种PFGE分子型别。结论 上海市浦东新区食源性小肠结肠炎耶尔森菌暴露风险以禽类制品和畜类制品为主，优势菌型为1A/O：8/ystB，虽无典型产毒株特征但仍有潜在致病力。菌株耐药率处于较低水平但存在多重耐药株，PFGE分子型别提示菌株呈高度遗传多样性。

Antimicrobial resistance and molecular epidemiology of foodborne Yersinia enterocolitica in Pudong New District, Shanghai

Objective To investigate the antimicrobial resistance and molecular epidemiology of foodborne Yersinia (Y.) enterocolitica in Pudong New District of Shanghai. Methods Four kinds of raw food samples were collected in retail circulation sites in Pudong from 2012 to 2016. Cold enrichment method was used to isolate Y. enterocolitica and further detection of biotype, serotype, virulent genes, antimicrobial susceptibility of the isolates and pulsed field gel electrophoresis (PFGE) were conducted. Results A total of 3 900 raw food samples were collected during this period, including poultry product (n=590), livestock product (n=1 074), aquatic product (n=1 488), vegetable (n=748), in which 111 (2.8%) were contaminated by Y. enterocolitica. The detection rates of Y. enterocolitica in poultry product samples (5.3%, 31/590) and livestock product samples (4.5%, 48/1 074) were higher than those in aquatic product samples (1.6%, 24/1 488) and vegetable samples (1.1%, 8/748). The predominant biotype was 1A (95.5%) and predominant serotype was O:8 (42.3%). All the strains lacked ail, ystA, yadA and virF genes, which encoded pathogenic Y. enterocolitica. Seventy six (68.5%) strains harbored ystB gene, in which 35 (31.5%) belonged to 1A/O:8/ystB pattern. Most strains were resistant to ampicillin (74.8%) and amoxicillin/clavulanic acid (70.3%), and non-sensitive rate to Cefoxitin was over 50.0%. No third generation cephalosporin or fluoroquinolone resistant strains were detected, but 38.7% (43/111) strains were multidrug resistant (MDR). Serotype O:8 and O:5 strains had 44 and 18 PFGE patterns, respectively. Conclusions The main foodborne exposure sources of Y. enterocolitica in raw food were poultry and livestock products in Pudong New District. 1A/O:8/ystB was the predominant pattern with potential pathogenicity despite lacks of typical pathogenic virulent genes. The antimicrobial resistant rates of Y. enterocolitica were at a low level, but MDR strains still existed. Molecular types of the isolates showed highly genetic diversity.