title: Non-typhoidal Salmonella serotypes, antimicrobial resistance and co-infection with parasites among patients with diarrhea and other gastrointestinal complaints in Addis Ababa, Ethiopia.
abstract: BACKGROUND
  Non-typhoidal Salmonella (NTS) is an important public health problem worldwide. Consumption of animal-derived food products and direct and/or indirect contact with animals are the major routes of acquiring infection with NTS. Published information, particularly on the serotype distribution of NTS among human patients with gastroenteritis and associated risk factors, is scarce in Ethiopia. This study investigated the prevalence, risk factors, serotype distribution and antimicrobial susceptibility of Salmonella species among diarrheic out-patients attending health centers in Addis Ababa and patients with various gastrointestinal complaints at Tikur Anbessa Specialized Hospital (TASH).
  
  
  METHODS
  Stool samples were cultured for Salmonella species according to the WHO Global Foodborne Infections Network laboratory protocol. Salmonella serotyping was conducted using slide agglutination and microplate agglutination techniques. Antibiotic susceptibility testing was performed using the disk diffusion method according to Clinical and Laboratory Standards Institute guidelines.
  
  
  RESULTS
  A total of 59 (6.2 %) stool samples, out of 957 were culture positive for Salmonella species. Fifty-five (7.2 %) of 765 diarrheic patients from health centers and 4 (2.1 %) of 192 patients from TASH were culture positive for Salmonella species. Multivariable logistic regression analysis after adjusting for all other variables revealed statistically significant association of Salmonella infection with consumption of raw vegetables (OR = 1.91, 95 % CI = 1.29-2.83, χ(2) = 4.74, p = 0.025) and symptom of watery diarrhea (OR = 3.3, 95 % CI = 1.23-8.88, χ(2) = 10.54, p = 0.005). Eleven serotypes were detected, and the most prominent were S. Typhimurium (37.3 %), S. Virchow (34 %), and S. Kottbus (10.2 %). Other serotypes were S. Miami, S. Kentucky, S. Newport, S. Enteritidis, S. Braenderup, S. Saintpaul, S. Concord and S. V:ROUGH-O. Resistance to three or more antimicrobials was detected in 27 (40.3 %) of the isolates. Resistance to five or more antimicrobials was detected in 17 (25.4 %). Resistance to individual antimicrobials was found at varying proportions: streptomycin (50; 74.6 %), nitrofurantoin (27; 40.3 %), sulfisoxazole (26; 38.8 %), kanamycin (23; 34.3 %), cephalothin (12; 17.9 %), and ampicillin (11; 16.4 %) respectively. Two S. Kentucky, one S. Typhimurium and one S. Concord isolates were multi-drug resistant to more than 10 antimicrobials.
  
  
  CONCLUSIONS
  The study demonstrated significant association of Salmonella infection with consumption of raw vegetables. There was no significant association of Salmonella infection with co-occurring parasites. The study also showed the dominance of S. Typhimurium and S. Virchow in primary health care units. Overall, prevalence of MDR was low compared to previous studies. Although their proportion was low, S. Kentucky and S. Concord demonstrated wider spectrum of MDR. Continuous monitoring of circulating serotypes, antimicrobial resistance profile and characterization on molecular resistance determinants is essential for proper treatment of patients and for identifying potential environmental origins of antimicrobial resistance.
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 Veterinary Preventive Medicine, The Ohio State University, 1920 Coffey Rd., Columbus, Ohio, 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: 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
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
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000627:therapeutic use; D000890:Anti-Infective Agents / Q000494:pharmacology / Q000627:therapeutic use; D060085:Coinfection / Q000188:drug therapy; D003430:Cross-Sectional Studies; D003967:Diarrhea / Q000453:epidemiology / Q000382:microbiology* / Q000469:parasitology*; D024881:Drug Resistance, Bacterial / Q000187:drug effects*; D005002:Ethiopia; D005260:Female; D005767:Gastrointestinal Diseases / Q000382:microbiology / Q000469:parasitology; D006801:Humans; D008297:Male; D010271:Parasites; D012475:Salmonella / Q000145:classification / Q000187:drug effects* / Q000302:isolation & purification / Q000472:pathogenicity; D012480:Salmonella Infections / Q000188:drug therapy* / Q000453:epidemiology / Q000382:microbiology; D014435:Typhoid Fever / Q000382:microbiology
chemical_list: D000900:Anti-Bacterial Agents; D000890:Anti-Infective Agents