title: Fecal prevalence, serotype distribution and antimicrobial resistance of Salmonellae in dairy cattle in central Ethiopia.
abstract: BACKGROUND
  Salmonellae are major worldwide zoonotic pathogens infecting a wide range of vertebrate species including humans. Consumption of contaminated dairy products and contact with dairy cattle represent a common source of non-typhoidal Salmonella infection in humans. Despite a large number of small-scale dairy farms in Addis Ababa and its surrounding districts, little is known about the status of Salmonella in these farms.
  
  
  RESULTS
  Salmonella was recovered from the feces of at least one animal in 7.6% (10/132) of the dairy farms. Out of 1203 fecal samples examined, 30 were positive for Salmonella resulting in a weighted animal level prevalence of 2.3%. Detection of diarrhea in an animal and in a farm was significantly associated with animal level (p = 0.012) and herd level (p < 0.001) prevalence of Salmonella. Animal level prevalence of Salmonella was significantly associated with age (p = 0.023) and study location; it was highest among those under 6 months of age and in farms from Adaa district and Addis Ababa (p < 0.001). Nine different serotypes were identified using standard serological agglutination tests. The most frequently recovered serotypes were Salmonella Typhimurium (23.3%), S. Saintpaul (20%), S. Kentucky (16.7%) and S. Virchow (16.7%). All isolates were resistant or intermediately resistant to at least one of the 18 drugs tested. Twenty-six (86.7%), 19 (63.3 %), 18 (60%), 16 (53.3%) of the isolates were resistant to streptomycin, nitrofurantoin, sulfisoxazole and tetracycline , respectively. Resistance to 2 drugs was detected in 27 (90%) of the isolates. Resistance to 3 or more drugs was detected in 21 (70%) of the isolates, while resistance to 7 or more drugs was detected in 11 (36.7%) of the isolates. The rate of occurrence of multi-drug resistance (MDR) in Salmonella strains isolated from dairy farms in Addis Ababa was significantly higher than those isolated from farms outside of Addis Ababa (p = 0.009). MDR was more common in S. Kentucky, S. Virchow and S. Saintpaul.
  
  
  CONCLUSIONS
  Isolation of Salmonella serotypes commonly known for causing human salmonellosis that are associated with an MDR phenotype in dairy farms in close proximity with human population is a major public health concern. These findings imply the need for a strict pathogen reduction strategy.
authors.affiliation: Aklilu Lemma Institute of Pathobiology, Addis Ababa University, P.O. Box 1176, Addis Ababa, Ethiopia. tadesse.eguale@aau.edu.et.
authors.forename: Tadesse
authors.initials: T
authors.lastname: Eguale
authors.affiliation: Department of Pharmacology and Clinical Pharmacy, School of Pharmacy, College of Health Sciences, Addis Ababa University, Churchill Avenue, P.O. Box 1176, Addis Ababa, Ethiopia. ephrem.engidawork@aau.edu.et.
authors.forename: Ephrem
authors.initials: E
authors.lastname: Engidawork
authors.affiliation: Department of Veterinary Preventive Medicine, The Ohio State University, 1920 Coffey Rd., Columbus, OH, 43210, USA. Gebreys.1@osu.edu.
authors.forename: Wondwossen A
authors.initials: WA
authors.lastname: Gebreyes
authors.affiliation: Department of Microbiology, Immunology & Parasitology, School of Medicine, College of Health Sciences, Addis Ababa University, Churchill Avenue, P.O. Box 9086, Addis Ababa, Ethiopia. asratdan@gmail.com.
authors.forename: Daniel
authors.initials: D
authors.lastname: Asrat
authors.affiliation: Aklilu Lemma Institute of Pathobiology, Addis Ababa University, P.O. Box 1176, Addis Ababa, Ethiopia. haileale@yahoo.com.
authors.forename: Haile
authors.initials: H
authors.lastname: Alemayehu
authors.affiliation: Aklilu Lemma Institute of Pathobiology, Addis Ababa University, P.O. Box 1176, Addis Ababa, Ethiopia. gtmedhin@yahoo.com.
authors.forename: Girmay
authors.initials: G
authors.lastname: Medhin
authors.affiliation: Laboratory for Foodborne Zoonoses, 110 Stone Road West, Guelph, ON, N1G 3W4, Canada. Roger.Johnson@phac-aspc.gc.ca.
authors.forename: Roger P
authors.initials: RP
authors.lastname: Johnson
authors.affiliation: Department of Microbial Infection and Immunity, Center for Microbial Interface Biology, The Ohio State University, Biomedical Research Tower, 460 West 12th, Columbus, OH, 43210-1214, USA. John.Gunn@Osumc.edu.
authors.forename: John S
authors.initials: JS
authors.lastname: Gunn
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D002417:Cattle; D002418:Cattle Diseases / Q000453:epidemiology / Q000382:microbiology; D003430:Cross-Sectional Studies; D024881:Drug Resistance, Bacterial; D005002:Ethiopia / Q000453:epidemiology; D005243:Feces / Q000382:microbiology*; D005260:Female; D006801:Humans; D008297:Male; D008826:Microbial Sensitivity Tests; D015995:Prevalence; D012475:Salmonella / Q000145:classification / Q000187:drug effects / Q000235:genetics / Q000302:isolation & purification*; D012480:Salmonella Infections / Q000382:microbiology; D012481:Salmonella Infections, Animal / Q000382:microbiology*; D065288:Serogroup
chemical_list: D000900:Anti-Bacterial Agents