Prevalence and molecular detection of multidrug-resistant Salmonella spp. isolated from eggshells in the local markets of Dhaka, Bangladesh

Abstract

Background and Aim: Salmonella spp. are frequently associated with various parts of the egg, including the shell, and cause foodborne outbreaks worldwide. Antibiotic-resistant Salmonella spp. pose serious threats to human and animal health; therefore, preventive measures against these pathogens are important. This study aimed to isolate and characterize Salmonella spp. from eggshell samples from different local markets in Dhaka, Bangladesh. Materials and Methods: Salmonella spp. were recovered from eggshells by enrichment culture and biochemical tests and characterized through molecular amplification of Salmonella-specific genes. Antibiotic sensitivity testing and molecular detection of isolates were performed by disk diffusion method and polymerase chain reaction (PCR), respectively. The invA, fliC, and sdfI genes were used in PCR to identify the genus Salmonella, and the species Salmonella Typhimurium and Salmonella Enteritidis, respectively. Results: The prevalence of Salmonella spp. was recorded as 40%, in which S. Typhimurium was the predominant serotype. PCR analysis revealed that 100%, 59%, and 13.6% of these isolates possessed the invA, fliC, and sdfI genes, respectively. The isolates exhibited multidrug resistance phenotypes, with resistance (95.5%) toward tetracycline, sulfamethoxazole, and clindamycin and sensitivity (86.3%) toward chloramphenicol. Conclusion: The findings of this study reflect the potential of eggs as a reservoir of multidrug-resistant Salmonella spp.; therefore, we recommend the careful handling of eggs to avoid contamination from farm to market.