Objective: Yersinia enterocolitica which is an important foodborne pathogen causing illness in humans is an extremely heterogeneous species consisting of different subtypes. It has the intrinsic resistance to β-lactam antibiotics because of the production of β-lactamases, BlaA and BlaB. Y. enterocolitica exhibits variable susceptibilities to β-lactams. Materials and Methods:The expression of the blaA and blaB genes by polymerase chain reaction, and the susceptibility to some β-lactams including penicillins and cephalosporins using the broth microdilution and disk diffusion methods were determined. A total of 18 Y. enterocolitica isolates were examined.Results: Overall, 33.3% of these isolates carried the blaA and blaB genes, all of which were recovered from chicken meat. The wide range of MIC for ampicillin (≤2-128 µg/mL) and ceftazidime (≤0.0625-2 µg/mL) was also observed. Of the Y. enterocolitica isolates, 55.6% were resistant to ampicillin (≥32 µg/mL) while the remaining isolates (44.4%) were susceptible to ampicillin (≤ 8 µg/mL). All isolates were susceptible to ceftazidime at the concentration tested. According to the disk diffusion test, 55.6% and 33.3% of the isolates were resistant to ticarcillin and cefoxitin, respectively. No resistance to piperacillin and ceftriaxone was found. Conclusion:The results showed that the presence of the blaA and blaB genes and intrinsic resistance against penicillins and cephalosporins were variable among Y. enterocolitica food isolates. Furthermore, the blaA and blaB genes were expressed in most of the resistant isolates to β-lactams, which may indicate the contribution of the genes to the drug resistance.

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Background Cronobacter , an emerging foodborne pathogen, contaminates various foods such as ready-to-eat (RTE) food due to its ubiquitous nature. Consumption of food contaminated with Cronobacter can cause severe infections in children, elderly or immunocompromised people. Therefore, we aimed to assess the presence of Cronobacter spp. in RTE foods, popularly consumed products, and pose potential health threat for consumers, especially for risk groups.Results Out of 340 RTE food samples, 59 (17.4%) were contaminated with Cronobacter spp. in this study. The highest contamination rate was found in meat free cig koftes (51.9%, 14/27), followed by spices (46.7%, 7/15), cereals (30.8%, 4/13), and desserts (30.2%, 13/43). A total of 64 Cronobacter isolates were identified phenotypically and genotypically from the 59 ready-to-eat foods samples. Molecular characterization was accomplished by PCR targeting 16S rRNA, gluA , rpoB and cgcA genes. The 64 Cronobacter isolates were completely identified by the biochemical and rpoB , while the PCR targeting the cgcA gene failed to identify to eight isolates. In this study, we investigated major virulence characteristics contributing to the pathogenicity of Cronobacter spp. including the outer membrane protein A, zinc-metalloprotease, siderophore production and biofilm formation. Many Cronobacter isolates (>87%) had these virulence characteristics. All isolates and a type strain were characterized using ERIC-PCR and genetic profiles of cluster analysis showed that the isolates were highly heterogeneous and genetically diverse. Antimicrobial susceptibility of RTE isolates to 18 different antimicrobial agents was determined by the disc diffusion method. Most Cronobacter isolates with a rate of 81.3% were resistant to cephalothin, 32.8% to cefoxitin and 20.3% to ampicillin. All Cronobacter isolates were susceptible to gentamicin and trimethoprim/sulfamethoxazole. The multidrug resistance to at least three or more antimicrobial agents was detected in 18.8% of Cronobacter isolates.Conclusions Results indicate that RTE food harbors potential pathogenic Cronobacter species and is a possible transmission vehicle for Cronobacter infection in vulnerable person. So, there is a need to adopt hygienic practices and rigorous sanitization treatments to ensure microbiological safety of RTE food.