Multidrug-resistant Salmonella enterica serovars isolated from frozen chicken carcasses

Salmonella is a leading cause of foodborne illnesses worldwide. Given its importance to global public health and little data about its prevalence in frozen chicken carcasses marketed in developing countries, this study aimed to determine the prevalence, serotyping, and antimicrobial resistance profiles of Salmonella isolates from 200 frozen chicken carcasses vended in Mansoura, Egypt. Salmonella species were isolated from 78 (39%) of 200 frozen chicken carcasses examined. Of the 204 biochemically-identified Salmonella isolates, 152 were molecularly confirmed as Salmonella through the detection of the invA marker gene by PCR. Eleven different Salmonella serovars were identified, among which S. Typhimurium (24.3%, 37/152), S. Enteritidis (19.1%, 29/152), and S. Kentucky (16.4%, 25/152) were the most predominant serovars. All isolates were resistant to at least one antibiotic agent, while 2.6%, 15.8%, and 68.4% of them were classified as pan-drug resistant (PDR), extensively drug-resistant (XDR), and multi-drug resistant (MDR), respectively. Interestingly, 94.7%, 76.3%, 63.2%, 47.4%, 39.5%, 28.9%, 28.9%, 26.3%, 15.8%, and 2.6% of isolates were resistant to oxacillin, cephalothin, cefotaxime, nalidixic acid, sulphamethoxazole-trimethoprim, tetracycline, kanamycin, ampicillin, ciprofloxacin, and gentamicin, respectively. Our findings revealed widespread contamination of frozen chicken carcasses examined with MDR Salmonella serovars, which may pose a tremendous threat to public health.