中国六省份零售整鸡中沙门菌血清型分布和耐药性特征研究

Serotype distribution and antimicrobial resistance of Salmonella isolates from retail chicken carcasses in six provinces of China

目的 研究我国六省份零售环节整鸡中沙门菌血清型分布和耐药性特征。方法 于2010年8月至2012年3月，从北京、广东、吉林、江苏、内蒙古和陕西6个省份的共7个监测点零售市场中，每月采集冷冻、冷藏和现宰杀整鸡共计20份整鸡样品，连续采集12个月，共计1 680份样品，经PCR和生化鉴定获得2 629株沙门菌。使用Luminex结合传统血清凝集方法鉴定血清型，使用微量肉汤稀释法测定菌株对10类14种抗生素的耐药性，使用分子生物学方法测定环丙沙星（CIP）-头孢噻肟（CTX）-多黏菌素E（CT）耐药沙门菌相关耐药基因。结果 2 629株沙门菌中共检出17种血清群和58种血清型，B和D1血清群所占比例较高，分别占34.7%（913株）和31.0%（815株）；Enteritidis（30.8%，810株）、Indiana（17.6%，463株）、Infantis（10.6%，278株）3种血清型为优势血清型。共检出224株CIP-CTX双重耐药印第安纳沙门菌，3株对CT耐药，其中1株中含有mcr-1基因且ESBL阳性，耐受本研究中9类11种抗生素。结论 中国六省份零售整鸡中沙门菌分离株血清型较复杂，耐药性较严重；CIP-CTX双耐药沙门菌多为印第安纳血清型，该类沙门菌多重耐药严重且存在mcr-1阳性株。

Objective To obtain the serotype diversity and antimicrobial resistance of Salmonella isolates recovered from retail chicken carcasses for sale in six regions of China.Methods From August 2010 to March 2012, each month 20 retail chicken carcasses including freshly slaughtered, chilled and frozen samples were collected from supermarkets and farmer＇s markets in 7 monitoring sites in Beijing, Jilin province, Inner Mongolia Autonomous, Shanxi province, Jiangsu province and Guangdong province, respectively. Samples were routinely collected for 12 months for each site. 1 680 chicken carcasses were collected in total and 2 629 Salmonella strains were isolated by PCR and biochemical method. Luminex xMAP method and classical slide agglutination method were carried out to determine isolates＇ serotypes. Minimal inhibitory concentrations （MICs） of 10 classes of antimicrobials including 14 agents were determined using broth micro-dilution method. Mocular methods were used to determine antimicrobial resistance genes of CIP-CTX-CT co-resistant isolates.Results In all, 2 629 Salmonella isolates, there were 17 seorgroups and 58 serotypes, B and D1 were the dominant serogroups with rates of 34.7% （n=913） and 31.0% （n=815）, Enteritidis （30.8%, n=810）, Indiana （17.6%, n=463）, Infantis （10.6%, n=278） were the top three serovars. We found 224 CIP-CTX co-resistant S. Indiana containing 3 colistin resistant strains, one of them carrying mcr-1 gene and being ESBLs positive, which demonstrated a nine multi drug resistance against 11 antimicrobials tested.Conclusion These data began to describe the complicated serovar diversity and heavy antimicrobial resistance of Salmonella isolates recovered from retail chicken carcasses in six regions of China. The findings highlight the emergence of ciprofloxacin and cefotaxime co-resistant S. Indiana and also a mcr-1 positive S. Indiana with heavy multi drug resistance.