Occurrence, antimicrobial resistance, and molecular characterization of Salmonella enterica from chicken products and human in Wasit Governorate of Iraq

Abstract

Background: Salmonella infections are considered the most common foodborne pathogens responsible for zoonotic infections and food poisoning in humans and animal species such as birds. Antimicrobial resistance is considered a global anxiety, because it cause human public health repercussions, as well as lead to increase in animal morbidity and death. Aim: The aims of this study are the isolation and identification of Salmonella enterica, as well as to investigate the antimicrobial susceptibility test and the molecular characteristics using PCR and sequences for isolates from chicken products (eggs, livers and minced meat) and human in the Wasit Governorate of Iraq. Methods: A total of 300 samples (150 chicken product samples including eggs, livers, and minced meat, and 150 human fecal samples) were collected from the Wasit governorate of Iraq from January to December 2022. The bacterial isolation was done according to recommendations of ISO 6579 standard and the Global Foodborne Infections Network laboratory protocol WHO 2010. Serotyping test and Antimicrobial susceptibility test (AST) were done by using 19 antibiotic agents according to the recommendations of CLSI, 2022 by using disc diffusion susceptibility test and Vitik 2 test. Finally, the suspected isolates were confirmed using the conventional polymerase chain reaction (PCR) method and sequencing for a unique rRNA gene. Results: The results showed that the isolation percentage of S. enterica in chicken products was 8.66% (12% eggs, 6% livers and 8% minced meat), while in humans it was 4.6%. Also, showed 100% of S. Typhi in human. While, in chicken eggs S. Typhi, S. Typhimurium and S. Enteritidis were 50%, 33.33% and 16.66%, respectively. Also, showed 100% of S. Typhimurium in both livers and minced meat. The AST in human isolates showed resistance to Ampicillin, Cefotaxime, Ceftazidime, Cefepime, Amikacin, Gentamicin, Ciprofloxacin, Norfloxacin, and Ceftriaxone, while no resistance to Amoxicillin, Pipracillin, Ertapenem, Imipenem, Meropenem, Fosfomycin, Nitrofurantoin, Trimethoprim, Azithromycin, and Tetracycline. In chicken products isolates were resistance with different percentages to Amikacin, Gentamicin, Tetracycline, Ciprofloxacin, Norfloxacin, Nitrofurantoin, Ampicillin, Cefotaxime, Ceftazidime, Cefepime, and Trimethoprim; while no resistance to Amoxicillin, Pipracillin, Ertapenem, Imipenem, Meropenem, Fosfomycin, Azithromycin and Ceftriaxone. Sequencing by using rRNA gene was done for four PCR products. Conclusion: This study showed the presence of genetic mutations for S. enterica which led to variations in the molecular characteristics, and antimicrobial drug resistance of S. enterica isolated from chicken products and human.