Isolation of Rare Salmonella Serovars, Wangata and Penarth from Chicken in Nsukka, Nigeria

Introduction: Salmonella infections remain a veterinary and public health problem of major importance. Poultry birds are known to be one of the major reservoirs of Salmonella and could consequently act as a vehicular transmission route to humans. Rare Salmonella serovars, whose epidemiological and serological patterns are not well understood, are becoming increasingly common in Nigeria and other parts of the world. We report the isolation of Salmonella enterica serovars Wangata and Penarth, two serovars that had not been previously reported in chicken in Nigeria.

Materials and Methods: A total of 300 chickens comprising of 150 intensively reared and 150 free range chickens, from selected farms and live bird markets, were sampled via cloacal vent using sterile cotton swab tips according to the International Office of Epizootics (OIE) standards. Following standard bacteriological techniques, samples were pre-enriched in buffered peptone water, before transferring into Rappaport Vassiliadis medium and finally streaked onto Salmonella-Shigella agar (SSA). Salmonella spp. were identified biochemically and serotyped based on reaction with somatic (O), flagella (H), and capsular (Vi) antisera. Antibiotic susceptibility testing was performed following Kirby-Bauer (disk-diffusion) method.

Results: Out of the 300 samples, 4% (n = 12) were positive for salmonellae. The isolates comprise of 6 isolates of S. enterica ser Wangata, 5 S. enterica ser Enteritidis and 1 S. enterica ser Penarth. All the rare serotypes S. Wangata and S. Penarth were isolated from free range chickens, while S. Enteritidis was isolated from both intensively reared and free range chickens. There was no difference in the sensitivity pattern between the rare serovars and serovar Enteritidis to the antibiotics tested. S. Penarth had a higher MIC to Cotrimoxazole, but lower MBC for gentamicin and tetracycline.

Conclusions: Free range chickens could be vehicles for the transmission and/or reservoirs of the rare salmonellae serotypes in Nigeria. Any prophylactic program aimed at controlling these agents in poultry farms in Nigeria, must take into account the free range local chickens.

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