Contamination of broiler turkey farms by Salmonella spp. in Morocco: prevalence, antimicrobial resistance and associated risk factors

The authors present a study that estimates the prevalence, sensitivity to antibiotics and distribution of Salmonella spp. serotypes in 20 broiler turkey farm buildings in the north-west of Morocco. Each farm was inspected three times for this purpose; one batch of ten pools of five droppings per farm was sampled on each visit (n = 600) for analysis. The high isolation rate observed for Salmonella spp. (35%) and the serotypes isolated were alarming. The authors found 62 Salmonella-positive isolates and identified nine serotypes: S. Kentucky (21 isolates, 33.8%), S. Parkroyal (10 isolates, 16.3%), S. Agona (7 isolates, 11.3%), S. Saintpaul (6 isolates, 9.6%), S. Typhimurium (5 isolates, 8%), S. Enteritidis and S. Heidelberg (4 isolates each, 6.4%), S. Newport (3 isolates, 4.8%) and S. Ruzizi (2 isolates, 3.2%). The Salmonella spp. antimicrobial resistance results showed that 93.5% (58/62) of the strains were resistant to at least one antibiotic. Multi-resistant strains (resistant to three or more antibiotics) accounted for 80.64% of the strains isolated. The percentage with resistance to ceftazidime (third-generation cephalosporin), ceftriaxone and cefotaxime was lower at 4.8%. Three strains of S. Agona with extended-spectrum beta-lactamase were detected, with a high level of resistance to ceftriaxone and a minimum inhibitory concentration of 16 mu g/ml. The variables associated with contamination are linked to: the cleanout period (p = 0.037); antibiotic treatment (p = 0.001); infection of turkey poults at placement (p = 0.002); manure storage (p = 0.003); keeping sick turkeys in the turkey house (p = 0.009); the season (p = 0.001); and the age of the turkeys at the time of sampling (p = 0.01).