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. 2018 Apr 16:7:53.
doi: 10.1186/s13756-018-0345-x. eCollection 2018.

Prevalence, identification of virulence factors, O-serogroups and antibiotic resistance properties of Shiga-toxin producing Escherichia coli strains isolated from raw milk and traditional dairy products

Reza Ranjbar  1 , Farhad Safarpoor Dehkordi  2 , Mohammad Hossein Sakhaei Shahreza  3 , Ebrahim Rahimi  4
Affiliations

Prevalence, identification of virulence factors, O-serogroups and antibiotic resistance properties of Shiga-toxin producing Escherichia coli strains isolated from raw milk and traditional dairy products

Reza Ranjbar et al. Antimicrob Resist Infect Control. .

Abstract

Background: Shiga-toxigenic Escherichia coli strains are one of the most important foodborne bacteria with an emergence of antibiotic resistance. Foodborne STEC strains are mainly associated with presence of certain virulence factors and O-seogroups. The present investigation was done to study the distribution of virulence factors, O-serogroups and antibiotic resistance properties of Shiga-toxigenic Escherichia coli isolated from milk and dairy products.

Methods: Six-hundred samples were randomly collected and immediately transferred to laboratory. All samples were cultured and E. coli strains were isolated. STEC strains were identified based on the presence of putative virulence factors and subtypes. STEC isolates were subjected to multiplex PCR and disk diffusion methods.

Results: One-hundred and eighty-one out of 600 samples (30.16%) harbored E. coli. Prevalence of STEC strains was 10.66%. O157 (43.75%) and O26 (37.50%) were the most frequently identified serogroups. Aac(3)-IV (100%), CITM (96.87%) and tetA (76.56%) were the most commonly detected antibiotic resistance genes. STEC strains had the highest prevalence of resistance against ampicillin (100%), gentamicin (100%) and tetracycline (96.87%).

Conclusions: Kashk and dough were negative for presence of E. coli strains. High prevalence of resistant-O157 strains and simultaneous presence of multiple virulence factors pose an important public health problem regarding the consumption of raw milk and dairy products.

Keywords: Antibiotic resistance; Molecular characterization; Shiga toxin producing Escherichia coli.

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Conflict of interest statement

The study was approved by the Ethical Committee of Research of the Molecular Biology Research Center, Baqiyatallah University of Medical Sciences, Tehran, Iran (Consent Ref Number 96-114). Verification of this research project and the licenses related to sampling process were approved by Prof. Reza Ranjbar and Prof. Ebrahim Rahimi (Approval Ref Number FST-96-114).There was no consent for publication.The authors declare that they have no competing interests.Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Figures

Fig. 1
Fig. 1
Seasonal prevalence of Escherichia coli strains in raw milk and traditional dairy product samples
Fig. 2
Fig. 2
Prevalence of multi-drug resistant STEC bacteria isolated from raw milk and traditional dairy product samples
See this image and copyright information in PMC

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