Prevalence and antimicrobial resistance of Salmonella isolated from lactating cows and in contact humans in dairy farms of Addis Ababa: a cross sectional study

a cross sectional study was conducted in Addis Ababa by collecting milk and faecal samples from lactating cows and stool samples from humans working in dairy farms. Samples were pre-enriched in buffered peptone water followed by selective enrichment using selenite cysteine and Rapaport-Vassilidis broths. Isolation and identification was made by inoculating the selectively enriched sample on to Xylose Lysine Deoxycholate agar followed by confirmation of presumptive colonies using different biochemical tests. The Kibry Bauer disk diffusion method was used for antimicrobial sensitivity testing.10.7% (21/195) of cows and 13.6% (3/22) of the human subjects sheded Salmonella. 83% resistance to two or more antimicrobials and 100% resistance to ampicillin were observed. Most of the isolates were relatively sensitive to ciprofloxacin, cotrimoxazole, and chloramphenicol.High proportion of Salmonella isolates developed resistance to the commonly prescribed antimicrobials and this may be a considerable risk in the treatment of clinical cases. So, wise use of antimicrobials must be practiced to combat the ever increasing situation of antimicrobial resistance.Salmonella are the major pathogenic bacteria in humans as well as in animals. Salmonella species are leading causes of acute gastroenteritis in several countries and salmonellosis remains an important public health problem worldwide, particularly in the developing countries [1]. Salmonellosis is the most common food borne disease in both developing and developed countries, although incidence rates vary according to the country [2]. The fecal wastes from infected animals and humans are important sources of bacterial contamination of the environment and the food chain [3].Antimicrobial-resistant Salmonella are increasing due to the use of antimicrobial agents in food animals at sub-therapeutic level or prophylactic doses which may promote on-farm selection of antimicrobial resistant strains and markedly increase the human heal