Tüketime hazır gıdalarda Cronobacter spp.'nin yaygınlığı, moleküler karakterizasyonu, virülans faktörleri ve antimikrobiyal dirençliliği

The Cronobacter spp. are a member of the family Enterobacteriaceae, Gram-negative, non-spore forming and facultative anaerobic bacteria. Cronobacter species are opportunistic pathogens that can cause severe diseases such as meningitis, sepsis, and necrotizing enterocolitis in immunocompromised individuals, neonates, infants and elderly adults. In the present study, a total of 340 ready-to-eat foods were tested for the presence of Cronobacter spp. The 59 (17.4%) of the 340 tested samples were positive for Cronobacter spp. Out of the contaminated samples with Cronobacter, the 64 Cronobacter isolates were obtained. The phenotypically identified Cronobacter isolates were also confirmed genotypically by the 16S rRNA, gluA gene and species-specific rpoB gene amplification. Overall, out of all samples, 64 isolates were identified as 39 (61%) Cronobacter sakazakii, 15 (23.4%) as Cronobacter malonaticus, 3 (4.7%) as Cronobacter muytjensii, 3 (4.7%) as Cronobacter dublinensis, 2 (3.1%) as Cronobacter turicensis and 2 (3.1%) Cronobacter universalis. All Cronobacter isolates were examined for the presence of genes encoding some virulence factors including outer membrane protein A (ompA) and zinc-containing metalloprotease (zpx). Of the 64 Cronobacter isolates, 63 (98.5%) were positive for both the ompA and zpx gene. In all Cronobacter isolates, other virulence determinants such as biofilm formation and siderophore production, which have a role in adhesion, invasion, and survival of bacteria, were detected. Out of the 64 Cronobacter isolates, 64 (100%) and 56 (87.5%) were found to be positive for siderophore production and biofilm formation, respectively. In this study, the results of ERIC-PCR showed the amplification bands, ranging from 3 to 12, among the 64 Cronobacter isolates and C. sakazakii ATCC 29544 as a reference strain. ERIC-PCR fingerprints revealed that all the Cronobacter divided into 12 genotypes. The results demonstrated that there was no a direct relationship between ERIC-PCR fingerprints and sources of the isolation. In this study, the antimicrobial susceptibility of the 64 Cronobacter spp. from ready-to-eat foods to commonly used 18 antimicrobial agents was examined. Most Cronobacter spp. with a rate of 81.3% were resistant to cephalothin, 32.8% to cefoxitin and 20.3% to ampicillin. All the Cronobacter isolates were susceptible to gentamicin and trimethoprim/sulfamethoxazole. The present study is remarkable that it provides a current data on the isolation and identification of Cronobacter spp., some virulence characteristics, and genetic variation by the ERIC-PCR and antimicrobial resistance profiles of Cronobacter spp. The monitoring the presence of Cronobacter spp. as an emerging pathogen in food is essential for the health of consumers.