Antibiotic Susceptibilities of Salmonella Serotypes Isolated from Visceral Organs of Post-mortem Chickens during Outbreaks in South-western Nigeria

Aim: Antimicrobial susceptibility profile of some motile Salmonella serotypes isolated from outbreaks of salmonellosis in commercial and backyard poultry farms were investigated in this study, to determine the therapeutic effectiveness of some common antimicrobial drugs used in Veterinary and Medical practices.

Place and Duration of the Study: Samples were collected from Lagos, Ogun and Oyo States, Nigeria. Bacterial culture and isolation; and antimicrobial susceptibility testing were carried out in the Department of Veterinary Microbiology, Federal University of Agriculture, Abeokuta. Confirmation of Salmonella isolates using Polymerase chain reaction (PCR) was done at the Biotechnology Laboratory, National Veterinary Research Institute, Vom. Serotyping was carried out at the World Organization for Animal Health/OIE, Italian Reference Laboratory for Salmonella, Istituto Zooprofilattico Sperimentale delle Venezie, Podava, Italy. The work was carried out over a period of 1 year between January and December, 2013.

Methodology: Tissue samples of the lungs, heart, liver, spleen, kidneys, proventriculus, small intestine, caecum and bile samples caecum from chickens submitted for postmortem examinations during outbreaks of salmonellosis were collected for bacterial isolation and identification. Confirmed Salmonella isolates were serotyped using the White-Kauffmann-Le Minor Scheme. The susceptibility profiles of the isolates were determined by the disc-diffusion method.

Results: The Salmonella serotypes were Salmonella Zega, S. Kentucky, S. Herston, S. Nima, S. Telelkebir, S. Colindale and S. Tshiongwe. All the seven Salmonella serotypes were 100% sensitive to Gentamycin, Ciprofloxacin, Enrolfloxacin, Ofloxacin, and Pefloxacin, but were 100% resistant to Erythromycin, Co-trimoxazol, Penicillin, and Ampicillin. They showed intermediate sensitivity to Cephalexin, Amoxycillin, Augumentin, Chloramphenicol, Ceftriaxone, Ceftazidime, Nolidixic acid, Oxacillin, Anicillin and Nitrofurontoin.

Conclusion: Salmonella serotypes identified in this study showed sensitivity to some antibiotics but were multidrug resistant (MDR) to various types used in both Veterinary and Medical practices, posing a serious therapeutic and public health challenges. All 7 Salmonella serotypes were resistant to 4 antibiotics. Also, all were MDR. We recommend for Polymerase chain reaction as a fast and accurate method for the detection of Salmonella species, and antibiotics testing before treatment in cases of outbreaks of avian salmonellosis.