Purpose: The aim of this study was to evaluate the effect of different layer housing systems on the prevalence, persistence and antimicrobial resistance of Campylobacter isolated from commercial laying hens.
Methods: Over 10 months, 355 samples were collected from five different housing types. A total of 123 isolates recovered from environmental and eggshell samples were presumptively identified as Campylobacter spp. by serological tests. Subsequent biochemical identification and real-time PCR assays were performed for confirmation of Campylobacter. Antimicrobial resistance of Campylobacter was determined using the National Antimicrobial Resistance Monitoring System (NARMS) protocol and genetic variability was assessed by PFGE.
Results: Following PCR, 58% of isolates were confirmed as Campylobacter spp., with 91.7% being Campylobacter jejuni and 8.3% being Campylobacter coli. Samples taken from conventional cages had the highest Campylobacter prevalence (23.21%) while those recovered from enrichable cages had the lowest (13.33%). Results demonstrated a high resistance to tetracycline (58%) followed by resistance to nalidixic acid (1.4%); both important antimicrobials for human medicine. The PFGE fingerprinting of Campylobacter isolates showed nine types with one leading PFGE type comprising 39% of isolates. Results showed no correlation (P>0.05) between Campylobacter prevalence and antimicrobial resistance among the housing types studied.
Significance: Findings from this study are concerning and illustrate the need for appropriate interventions to prevent drug-resistant Campylobacter spread among laying hens.