Prevalence, phenotypic and genotypic characterization, virulence potential and antimicrobial resistance of Cronobacter species from ready-to-eat foods

Abstract

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.