发酵乳制品中大肠杆菌菌株的毒力因子、血清群和抗菌抗性特性
Virulence factors, serogroups and antimicrobial resistance properties of Escherichia coli strains in fermented dairy products.
作者信息
Dehkordi Farhad Safarpoor, Yazdani Farshad, Mozafari Jalal, Valizadeh Yousef
机构信息
Young Researchers Club and Elite, ShahreKord Branch, Islamic Azad University, P,O, Box 166, ShahreKord, Iran.
出版信息
BMC Res Notes. 2014 Apr 7;7:217. doi: 10.1186/1756-0500-7-217.
BACKGROUND
From a clinical perspective, it is essential to know the microbial safety of fermented dairy products. Doogh and kashk are fermented dairies. These products are used by millions of people but their microbial qualities are unknown. Shiga toxin producing Escherichia coli (STEC) is one of the most commonly detected pathogens in the cases of food poisoning and food-borne illnesses. The present investigation was carried out in order to study the molecular characterization and antimicrobial resistance properties of STEC strains isolated from fermented dairy products.
METHODS
Six hundred fermented dairy samples were collected and immediately transferred to the laboratory. All samples were cultured immediately and those that were E. coli-positive were analyzed for the presence of O157 , O26, O103, O111, O145, O45, O91, O113, O121 and O128 STEC serogroups, tetA, tetB, blaSHV, CITM, cmlA, cat1, aadA1, dfrA1, qnr, aac (3)-IV, sul1 and ereA antibiotic resistance genes and stx1, stx2, eaeA, ehly, cnf1, cnf2, iutA, cdtB, papA, traT, sfaS and fyuA virulence factors using PCR. Antimicrobial susceptibility testing was performed also using disk diffusion methodology with Mueller-Hinton agar.
RESULTS
Fifty out of 600 (8.33%) dairy samples harbored E. coli. In addition, yoghurt was the most commonly contaminated dairy. O157 (26%) and O26 (12%) were the most commonly detected serogroups. A significant difference was found between the frequency of Attaching and Effacing E. coli and Enterohaemorrhagic E. coli (P <0.05). Stx1 (44%), eae (36%), papA (32%) stx2 (30%), and ehly (28%) were the most commonly detected virulence factors. The genes encode resistance against tetracycline (tetA and tetB) (76% and 70%, respectively), cephalothin (blaSHV) (38%), ampicillin (CITM) (36%) and gentamicin (aac (3)-IV) (32%) were the most commonly detected. High resistance levels to tetracycline (84%), penicillin (46%), ampicillin (38%) and streptomycin (36%) were observed.
CONCLUSION
Fermented dairy products can easily become contaminated by antibiotic resistant STEC strains. Our findings should raise awareness about antibiotic resistance in Iran. Clinicians should exercise caution when prescribing antibiotics, especially in veterinary treatments.
背景
从临床角度来看，了解发酵乳制品的微生物安全性至关重要。杜格（Doogh）和卡什克（kashk）是发酵乳制品。数以百万计的人食用这些产品，但其微生物质量未知。产志贺毒素大肠杆菌（STEC）是食物中毒和食源性疾病案例中最常检测到的病原体之一。本次调查旨在研究从发酵乳制品中分离出的STEC菌株的分子特征和抗菌耐药特性。
方法
收集了600份发酵乳制品样本，并立即送往实验室。所有样本立即进行培养，对大肠杆菌呈阳性的样本分析O157、O26、O103、O111、O145、O45、O91、O113、O121和O128 STEC血清型、tetA、tetB、blaSHV、CITM、cmlA、cat1、aadA1、dfrA1、qnr、aac(3)-IV、sul1和ereA抗生素耐药基因以及stx1、stx2、eaeA、ehly、cnf1、cnf2、iutA、cdtB、papA、traT、sfaS和fyuA毒力因子的存在情况，采用聚合酶链反应（PCR）。还使用含穆勒-欣顿琼脂的纸片扩散法进行抗菌药敏试验。
结果
600份乳制品样本中有50份（8.33%）含有大肠杆菌。此外，酸奶是最常被污染的乳制品。O157（26%）和O26（12%）是最常检测到的血清型。在黏附性和侵蚀性大肠杆菌与肠出血性大肠杆菌的频率之间发现了显著差异（P<0.05）。stx1（44%）、eae（36%）、papA（32%）、stx2（30%）和ehly（28%）是最常检测到的毒力因子。编码对四环素（tetA和tetB）（分别为76%和70%）、头孢噻吩（blaSHV）（38%）、氨苄青霉素（CITM）（36%）和庆大霉素（aac(3)-IV）（32%）耐药的基因是最常检测到的。观察到对四环素（84%）、青霉素（46%）、氨苄青霉素（38%）和链霉素（36%）的高耐药水平。
结论
发酵乳制品很容易被耐抗生素的STEC菌株污染。我们的研究结果应提高伊朗对抗生素耐药性的认识。临床医生在开抗生素处方时应谨慎，尤其是在兽医治疗中。
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