The characterization of Salmonella serovars isolated from apparently healthy slaughtered pigs at Addis Ababa abattoir, Ethiopia

We looked for Salmonella in all 278 apparently healthy pigs slaughtered between September 2004 and May 2005 at the only pig-slaughtering slaughterhouse in Addis Ababa, Ethiopia. We used standard methods and tested caecal contents, mesenteric lymph nodes, and carcass swabs from each pig (missing only one carcass swab). Of the 278 pigs, 120 (43%) were positive; of the 833 samples 173 (21%) were positive. Thirty-three percent of the isolates were multi-resistant (including 46/48 isolates of S. Hadar, but none of the 39 isolates of S. Eastbourne or of the 37 of S. Saintpaul). Resistance to streptomycin (32.4%), tetracycline (31.8%) and nitrofurantoin (27.2%) was relatively high. The most common pattern of MDR observed was to nitrofurantoin, streptomycin and tetracycline (Resistance type NitStrTet). Our results indicate that salmonellae are prevalent in pigs slaughtered at Addis Ababa abattoir and a large proportion of the isolates were multi-drug resistant.