The occurrence of multidrug-resistant Salmonella nagoya and other serovars in healthy commercial layers in Ilorin, Nigeria

Abstract

The occurrence of drug-resistant non-typhoidal Salmonella (NTS) in poultry has serious economic implications for the poultry industry and has the potential to cause human Salmonellosis. This study, therefore, aimed to determine the circulating serovars of NTS and their antibiotic susceptibility patterns in poultry in Ilorin. This cross-sectional study was conducted from January to March 2015. A total of 420 samples (cloacal, n=140; fecal, n=140; feed, n=70, and water, n=70) were aseptically collected from live adult birds from 14 farms using a systematic random sampling technique. Salmonella was isolated using the ISO 6579 method. Antibiotic sensitivity testing of NTS serovars was performed using the Kirby Bauer disc – diffusion method and interpreted using the epidemiological cut-off (ECOFF) values. The prevalence of NTS in poultry was 7.4% (n=31). Feed samples were the most contaminated samples (42%, n=13/31). Faecal sample (32%, n=10/31), cloacal swabs (19.5%, n= 6/31), and water samples (6.5%, n=2/31) also contained NTS. There was a significant difference between NTS isolation rates between farms (p<0.05). Only 21 isolates purposively selected across farms and sample types were serotyped. Salmonella nagoya was the most prevalent (52%, n=11/21). Other serovars were Salmonella brijbhumi (5%, n=1/21); Salmonella enteritidis (5%, n=1/21); and Salmonella enterica subsp. enterica serovar 6, 8: z4 (19%, n=4/21). Four isolates (19%) were untypable. All isolates showed multidrug resistance. Most of the isolates were resistant to ampicillin (82.3%) and tetracycline (76.5%). Some isolates were resistant to cefotaxime (23.5%) and ciprofloxacin (29.4%). The occurrence of multidrug-resistant salmonella isolates is considered a critical public health threat that requires urgent global action. There is a need for a coordinated national salmonella surveillance program in Nigeria.