Prevalence and antibiotic susceptibility of Salmonella in chicken eggs from farms in Zaria, Kaduna State, Nigeria

Abstract

The research was a cross-sectional study conducted from June to December 2021 within Zaria metropolis which aimed to determine the prevalence and antimicrobial susceptibility of Salmonella isolated from chicken egg shells and their contents. A total of 240 egg samples were collected from farms that operated on either battery cages or deep litter-rearing systems. The samples were transported in ice packs to the Department of Veterinary Public Health and Preventive Medicine, Ahmadu Bello University Zaria for laboratory procedures. Salmonella was isolated, identified and confirmed using standard techniques as outlined by the International Organization for Standardization while antimicrobial susceptibility was determined using the disc diffusion method as described by Kirby-Bauer. Out of the 240 eggs sampled, 12 Salmonella isolates were confirmed positive by amplifying the genus-specific invA gene. A Salmonella prevalence of 4.6% was calculated to be from the egg shells while 0.4% prevalence was from the egg contents. The antimicrobial susceptibility test revealed that there was resistance by Salmonella isolates to almost all the 14 antimicrobials used across 8 different classes of antibiotics except for Imipenem in which the isolates exhibited absolute susceptibility. A Fisher’s exact test was used to test the association between the variables. There was a significant association (P< 0.0059) between the difference in the prevalence of Salmonella on eggshell and egg content but there was no significant association (P>0.7689) between the battery cage and the deep litter systems of rearing. The study highlights the prevalence and the importance of continuous monitoring and surveillance for pathogenic Salmonellae.