陕西市售婴幼儿食品中阪崎克罗诺杆菌流行状况及相关特性研究

Prevalence and Relative Characterizations of Cronobacter sakazakii in Retail Infant and Baby Foods in Shaanxi Province

对陕西省62个品牌的366份市售婴幼儿配方乳粉和米粉及其他食品中阪崎克罗诺杆菌的污染状况进行调查,并对分离株的相关特性进行分析,旨在阐明陕西市售婴幼儿食品的食用安全性。结果表明,87份样品检出阪崎克罗诺杆菌阳性,平均检出率为23.8%。乳粉阳性样品检出率为18.3%,米粉为27.3%,其他婴幼儿配方食品检出率20.0%。共检出169株阪崎克罗诺菌,其中168(99.4%)株对利福平产生抗性,对其他抗生素耐药的菌株比例依次为阿莫西林20.12%、链霉素18.93%、四环素17.16%、氨苄西林12.43%、庆大霉素11.24%和头孢曲松0.59%等。135株(79.88%)分离株携带ompX基因,120株(71.01%)携带cpa基因、111株(65.68%)携带sip基因、93株(55.03%)携带hly基因。按照95%的相似性,169株分离株脉冲场凝胶电泳(Pulse field gel electrophoresis,PFGE)分型后可被分为4个大簇、8个小簇和1个单基因型,部分源于不同品牌或批次食品的菌株基因型相似性较高,表明陕西省市售婴幼儿配方粉及婴幼儿食品中阪崎克罗诺杆菌染问题不容忽视,存在严重的食品安全危胁。

Cronobacter sakazakii is a case-fatal foodborne pathogen,which can cause irreversible fatal injuries to newborn infant and people with weakened immune system to severe neonatal meningitis,enterocolitis and bacteremia.In present study,we investigated the prevalence of C.sakazakii in retail powdered infant formula(PIF),and infant and baby rice cereal(IBRC)that manufactured in domestic and foreign countries with various brands and sold in Shaanxi province to further understand the contamination status of this bacterium and to ensure food safety.Eighty seven(23.8%)of 366 PIF and IBRC samples,which belonged to 62 different brands,were positive for C.sakazakii.The positive rate of C.sakazakii was 18.3%for PIF,27.3%for IBRC,and was 20.0%for other infant and baby foods.Totally 169 C.sakazakii isolates were recovered from 366 samples,among the isolates,168(99.4%)resisted to rifampicin,and the percentage of resistance to other antibiotics were as followings,20.12%for amoxicillin,18.93%for streptomycin,17.16%for tetracycline,12.43%for ampicillin,11.24%for gentamicin and 0.59%for ceftriaxone.One hundred and thirty five(79.88%)carried ompX gene,120(71.01%)carried cpa gene,111(65.68%)carried sip gene,and 93(55.03%)carried hly gene.Based on a cutoff value of 95%similarity,the genotypic DNA profiles of 169 C.sakazakii isolates could be grouped into four big clusters,eight small clusters and one single genotype based on genotyping via pulse field gel electrophoresis(PFGE),and the genotypes of some isolates that derived from different foods with different brands and processing lots were same or similar.The results indicated that C.sakazakii contamination among PIF and IBRC was common,which is great potential threat to food safety,and more attention should be paid to this problem.