Prevalence and antibiotic resistance profile of Salmonella spp. in broiler carcasses from dominant poultry production areas in Bhutan

Abstract

Abstract Background: Salmonella is an important zoonotic pathogen and its infections are considered among the most commonly and widely distributed food-borne illness reported worldwide. Poultry products have been identified as important sources of Salmonella infection to humans. While there have been reports of high prevalence of Salmonella and multidrug resistance in imported chicken meat in Bhutan, the safety of nationally produced broiler meat with regards to Salmonella contamination is not known. In the absence of national surveillance of Salmonella in food animals in Bhutan, this study assessed the prevalence of Salmonella and its serotypes in broiler chicken carcass in the dominant poultry production areas of the country and determine its antibiotic susceptibility patterns. Methods: A cross-sectional study was conducted in January to April 2016 in all five major commercial broiler meat producers and suppliers in Bhutan located in the Samphelling and Darla gewogs. Following a systematic random sampling method, 36 broiler carcasses were sampled from each of the five broiler commercial farms producing the total sample size of 180 samples. Salmonella was isolated and identified following the International Organization for Standardization methods (ISO 6579:2002). All Salmonella isolates were subjected to antibiotic susceptibility testing (AST) following the procedures of the Clinical and Laboratory Standards Institute (CLSI) method. Results: The overall prevalence of Salmonella in broiler chicken meat samples was 12.78% (95% CI, 10.98 – 14.58). The prevalence of Salmonella spp. was higher in farms of the Samphelling gewog compared to Darla gewog [14.81% (95% CI, 8.2.7 – 21.5) vs 9.72% (95% CI, 2.9 – 16.6) respectively]. Among 23 Salmonella isolates, the most prevalent serovar was Salmonella ser. Typhi (73.9%). The Salmonella isolates showed high sensitivity to gentamicin (73.9% of isolates) followed by streptomycin (56.5%) and ampicillin (47.8%). The highest proportion of resistance was noted to tetracycline (95.6%), trimethoprim (86.9%), amoxicillin (65.2%), and ampicillin (47.8%). Among 23 Salmonella isolates, 60.87% (n=14) were considered multidrug resistant and 7 patterns of multidrug resistance were discovered. Conclusion: The estimates of Salmonella prevalence and multidrug resistance in nationally produced commercial broiler chicken carcasses from the two main broiler meat producing areas in Bhutan, raises significant public health concerns highlighting the need for an integrated national Salmonella surveillance program across the poultry market chain.