Molecular Characterization and Antibiogram of Salmonella Enterica and Its Non-Typhoidal Serotypes in Poultry Feed with Seasonal Effects in Karachi, Pakistan.
DOI:
https://doi.org/10.67773/bios.v7i2.262Keywords:
Total viable count,, Antimicrobial susceptibility test, Polymerase chain reaction, Foodborn pathogens, Seasonal effects.Abstract
Salmonella enterica and its non-typhoidal serotypes are major foodborne zoonotic pathogens responsible for salmonellosis, one of the most common gastrointestinal diseases worldwide. This study aimed to molecularly identify S. enterica and its non-typhoidal serotypes (S. Enteritidis and S. Typhimurium), evaluate the seasonal influence on bacterial growth, and determine their antimicrobial susceptibility profiles. A total of 204 poultry feed samples were analyzed using cultural and biochemical methods, followed by confirmation with polymerase chain reaction (PCR). Bacterial load was determined by total viable count (TVC), while antimicrobial susceptibility testing (AST) was performed using the disk diffusion method and minimum inhibitory concentration (MIC). Of the 204 samples, 66 (32.3%) were confirmed as S. enterica. Among these, 31 (46.9%) were identified as S. Typhimurium and 21 (31.8%) as S. Enteritidis. The highest mean bacterial load (7.026 × 10⁸ CFU/g) was recorded during June–August, while the lowest (2.395 × 10⁸ CFU/g) occurred during December–February, with a significant seasonal difference (p < 0.01). Antimicrobial susceptibility testing showed that all non-typhoidal S. enterica serotypes were highly resistant to penicillin and its derivatives but remained largely susceptible to fluoroquinolones and aminoglycosides. The high prevalence of Salmonella in poultry feed during hot and humid months highlights an increased risk of foodborne transmission. These findings emphasize the need for improved storage practices, enhanced pre-harvest control measures, and continuous surveillance of microbial contamination and antimicrobial resistance to safeguard public health.
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