Phenotypic and Molecular Detection of β-lactamase Genes blaTEM, blaCTX, and blaSHV Produced by Salmonella spp. Isolated from Poultry Meat

One of the most important and frequently encountered pathogens in the poultry supply chain is Salmonella. A comprehensive insight into its pathology and its counteractive mechanisms towards antibiotics, thus, is much needed. The determination of phenotype and molecular susceptibility along with the detection of β-lactamase genes produced by Salmonella isolated from poultry meat was the objective of the present study. Additionally, this study is significant due to the prevalence of Salmonella in Ardabil, a city in the northwest of Iran. The present study aimed to analyze the susceptibility of Salmonella isolates (collected from the commercial broilers (CB) and spent hens (SH)) towards the β-lactam class of wide-spectrum antibiotics. Further, the phenotypes of the isolates were investigated based on their extended-spectrum β-lactamase (ESBL) production. The test samples were collected from a total of 100 chicken carcasses comprising 50 from the retail CB and 50 from the SH procured from a local supermarket in Ardabil city. The Salmonella isolates were then analyzed for the production of β-lactamase enzymes under the standard laboratory conditions. 20 Salmonella strains were isolated from the 100 samples, with 55% (11/20) from the CB and the remaining 45% (9/20) from the SH. The isolated Salmonella spp. showed multiple β-lactam resistance phenotypes and the presence of β-lactamase genes. blaTEM was found to be the dominant β-lactamase gene (85%), followed by blaCTX-M (60%) and blaSHV (35%). Using clinical and laboratory standards institute extended-spectrum β-lactamase (CLSI ESBL) confirmatory test, 100% of the isolates were found to be ESBL producers, as also confirmed by the PCR method. This study revealed that a significant number of antibiotic-resistant Salmonella was isolated from the retail poultry meat samples of the CB and SH. Mortality and morbidity rates increase with the increase in the resistance of bacteria to standard antibiotics. Therefore, microbiological surveillance for different isolates of Salmonella should be done at the country level to monitor its antimicrobial resistance. The prime purpose of the current study was to centralize the focus in this regard, via two advanced detection procedures comprising phenotypic and molecular detection of β-lactamases enzymes produced by Salmonella isolates from poultry meat.