Prevalence and antibiotic resistance patterns of Salmonella isolates from lactating cows and in-contact humans in dairy farms, Northwest Ethiopia

Abstract

Background: Salmonellosis is an infectious disease of humans and animals caused by species of Salmonella. Salmonella are widespread in the environment and commonly found in farm effluents and sewage. Epidemiological information on the prevalence of salmmonelosis is a prerequisite to develop appropriate control strategies. Objective: To assess the prevalence and antibiotic resistance patterns of Salmonella isolates. Methods: A cross-sectional study was conducted. A total of 152 cows and 14 humans were included in the study. Milk, fecal sample and human stool were collected. Samples were pre-enriched with buffered peptone water and transferred to selenite cysteine broth and rappaport-vassilidis broth. Isolation was made by plating on to xylose lysine deoxycholate agar and brilliant green agar. Biochemical, antibiotic susceptibility testing and serotyping were done. Data were entered and analyzed using SPSS version 20 software. Binary logistic regression was applied and p-values of less than 0.05 were considered statistically significant. Results: Of the total 21 Salmonella isolates identified, 19(90.5%) and 2(9.5%) isolates were from lactating cows and in-contact individuals, respectively. Salmonella bredeney was the most common (85.7%). Drinking water source had statistically significant (P=0.027) association. All isolates were resistant at least to one of the antibiotics tested with 100% to ampicillin. All isolates were sensitive to ciprofloxacin and amoxacilin/clavulanic acid. Conclusion: Large percentage of Salmonella isolates were resistant at least to one of the antibiotics tested. Salmonellosis treatment could be difficult in the future unless wise use of antibiotics is practiced