Surveillance Study for Epidemiology of Extended spectrum B-lactamase and AmpC Encoding Salmonella Strains in Symptomatic Patients with Community Acquired Diarrhea and Chicken Meat Samples Distributed in 22 Regions of Tehran, Iran

Background and Objectives: Salmonella is a member of Enterobacteriacea and is globally considered as a main cause of foodborne diseases. Failure of antibiotic regimens against invasive infections of Salmonella in human could be caused through transmission of resistance genes from the strains existing in food animal reservoirs. To investigate this relationship, a prospective surveillance study was done in 22 regions of Tehran. Materials and Methods: Infection rate of Salmonella spp. in 400 symptomatic patients with diarrhea and contamination of 100 chicken meat samples distributed across 22 regions of Tehran were investigated. The Salmonella isolates were characterized by biochemical and molecular tests. Salmonella serogroups were determined based on Kaufmann-White scheme. Moreover, resistance patterns to 10 antibiotics and multidrug resistance patterns were detected, and AmpC/ESBL phenotypes were confirmed using AmpC detection Set. Statistical analyses were done to show correlation of the resistance phenotypes among common serogroups between the human and chicken meat isolates. Results: The poultry meat samples were related to 41 different brands, with their weights ranging from 0.76 Kg to 2.71 Kg. Salmonella was isolated from 75% of chicken meet samples, while it was isolated from 0.5% of the patients. Resistance to tetracycline (59%), trimethoprim/sulfamethoxazole (43%), azithromycin (42%), and chloramphenicol (27%) was common among the meat isolates; however, the human isolates showed lower frequency of the resistance patterns as follows: tetracycline (13.6%), trimethoprim/sulfamethoxazole (9.1%), and azithromycin (9.1%). MDR phenotype was detected in 4.5% of the Salmonella isolates from the human stool samples, while it was more frequent among the chicken meat isolates (45.3%). No correlation was found between the human and chicken meat isolates based on the characterized serogroups and the resistance phenotypes. AmpC and ESBL phenotypes were detected in one of the chicken meat isolates. The resistance patterns were not linked to specific brands of the chicken products, the production date, and city regions. Conclusion: Higher frequency of Salmonella strains with MDR and AmpC/ESBL phenotypes among the chicken meat samples is suggestive of their risks for transmission of resistance genetic markers to human adapted strains through food chain in Tehran.