Prevalence, antimicrobial resistance, and molecular characterization of salmonella in cattle, beef, and diarrheic patients in Bishoftu, Ethiopia

Authors: GUTEMA, FANTA - Addis Ababa University; RASSCHAERT, GEERTRUI - Flanders Research Institute For Agriculture; Agga, Getahun; MERERA, OLANA - Samara University; DUGUMA, ADDISU - Bishoftu Hospital; ABDI, RETA - Long Island University; DUCHATEAU, LUC - Ghent University; MATTHEUS, WESLEY - Ghent University; GABRIEL, SARAH - Ghent University; DE ZEUTTER, LIEVEN - Ghent University

Submitted to: Foodborne Pathogens and Disease
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/27/2020
Publication Date: 2/9/2021
Citation: Gutema, F.D., Rasschaert, G., Agga, G.E., Merera, O., Duguma, A.B., Abdi, R.D., Duchateau, L., Mattheus, W., Gabriel, S., De Zeutter, L. 2021. Prevalence, antimicrobial resistance, and molecular characterization of salmonella in cattle, beef, and diarrheic patients in Bishoftu, Ethiopia. Foodborne Pathogens and Disease. 18(4):283-289. https://doi.org/10.1089/fpd.2020.2869.
DOI: https://doi.org/10.1089/fpd.2020.2869

Interpretive Summary: Salmonella is a leading cause of foodborne infections in humans. It causes self limiting infections associated with gastrointestinal disturbances such as diarrhea in most healthy people. However, it can cause severe systemic infections that require antibiotic treatments in children, the elderly and the immune compromised individuals. Beef can be contaminated during processing through fecal transfer of bacteria from the intestine of infected cattle to the meat during slaughter operation. Cross contamination can occur during transportation, distribution and preparation. Consumption of undercooked or cross-contaminated beef after cooking is the major route of infection. In a study aimed to establish the role of cattle for human infection we observed higher prevalence in the retail beef than in cattle indicating cross contamination of beef during transportation, storage and distribution. We identified Salmonella serotypes that are commonly associated with human infections. Most of the Salmonella isolates were resistant to some of the antibiotics tested. Isolates from cattle and beef shared similar fingerprints suggesting that same strains were transferred from cattle to beef posing risk of infection to humans. Interventions during cattle production, processing and distribution, as well as public education are important prevention measures.

Technical Abstract: Within Ethiopia, there is a lack of information on the genetic relatedness of Salmonella from cattle, beef, and diarrheic patients and its potential transmission from cattle to humans through consumption of contaminated beef. The objective of this study was to assess the prevalence and determine the serotypes, genetic relatedness, and antimicrobial resistance of Salmonella in cattle in two local slaughterhouses, in beef at retail shops, and in diarrheic patients in the only hospital in Bishoftu, Ethiopia. Salmonella was detected in 2.5% (6/240) of cattle samples, in 8.7% (11/127) of beef samples, and in 2.3% (5/216) of the diarrheic patients. Four Salmonella serotypes: Salmonella Typhimurium, Salmonella Eastbourne, Salmonella Saintpaul, and Salmonella Cotham were identified. Salmonella Typhimurium and Salmonella Eastbourne were isolated from cattle and beef, whereas Salmonella Saintpaul and Salmonella Cotham were isolated only from diarrheic patients. Except for serotype Salmonella Saintpaul, all isolates were grouped into five pulsotypes, of which two pulsotypes contained isolates from cattle and beef. Isolates from humans represented unique pulsotypes. Among the 22 Salmonella isolates tested, 95.5% were resistant to at least 1 of the 14 antimicrobials tested. Three Salmonella isolates originating from cattle were multidrug resistant. One human isolate was susceptible to all antimicrobials tested. More specifically, resistance to ampicillin,sulfamethoxazole, tetracycline, tigecycline, and trimethoprim were observed. The most frequently observed resistance was to sulfamethoxazole (90.9%, 20/22) followed by trimethoprim (22.7%, 5/22). The study revealed considerable Salmonella contamination of beef at retail shops, antimicrobial resistance to commonly used antimicrobials, and shared genetically similar Salmonella serotypes between cattle and beef; the link with humans could not be established. Still, the findings of Salmonella in cattle and beef, the propensity of transfer of Salmonella from cattle to beef coupled with the common consumption of raw/undercooked beef are likely to pose public health risk in Ethiopia.