Detection of Listeria species, factors associated, and antibiogram of Listeria monocytogenes in beef at abattoirs, butchers, and restaurants of Ambo and Holeta Towns, Ethiopia
Authors: Gebremedhin Endrias Zewdu , Hirpa Gadisa , Borana Bizunesh Mideksa , Sarba Edilu Jorga , Marami Lencho Megersa , Tadese Nega Desalegn , Ambecha Hirut Abebe 
Published: May 2020

Background

Listeriosis is one of the globally distributed foodborne diseases with the highest fatality rate. Few studies were done on the occurrence of Listeria species from meat at abattoirs, butchers, and restaurants in Ethiopia, and there has been no study conducted at Ambo and Holeta town. The objectives of this study were to isolate and identify Listeria species, assess factors for contamination of meat, and antibiogram of Listeria monocytogenes along the meat chain in Ambo and Holeta towns, Central Ethiopia.
Methods

450 meat samples were collected from abattoirs (n = 150), butchers (n = 150) and restaurants (n = 150) for isolation and identification of Listeria species using primary culture and biochemical tests. A questionnaire survey and observational checklist were made to assess the potential risk factors for the occurrence of Listeria species such as factors related to socio-demographic characteristics, knowledge on hygiene and practice of food handlers. Pearson’s Chi-square and logistic regression analyses were used to assess factors contributing for contamination of meat with Listeria species. Kirby Bauer disc diffusion technique was applied to determine the antimicrobial susceptibility profile of Listeria monocytogenes isolates.
Results

The overall occurrence of Listeria species in both Ambo and Holeta towns was 28.44% (128/450; 95% confidence interval [CI]: 24.32–32.86%). The occurrence of L. monocytogenes was 4.4% (20/450; 95% CI: 2.74–6.78%), L. ivanovii 2.2% (10/450; 95% CI: 1.07–4.04%), L. seeligeri 1.78% (8/450; 95% CI: 0.8–3.47%), L. welshimeri 3.77% (17/450; 95% CI: 2.22–5.98%), L. inoccua 6.22% (28/450; 95% CI: 4.17–8.87%) and L. grayi 10.22% (46/450; 95% CI: 7.58–13.39%). The probability of contamination of meat in butchers and restaurants by the Listeria species were comparatively higher in high altitude (Holeta) than medium altitudes (Ambo) [OR = 4.91; 95% CI: 2.65–9.07%; p < 0.001], in dry than wet season [OR = 8.78; 95% CI: 2.66–28.99%; p < 0.001] and in butchers and restaurant where the employees work ≥ 9 hours per day than those working ≤ 8 hours per day (OR = 3.57; 95% CI:1.74–7.36%; p < 0.001]. Of the 20 Listeria monocytogenes isolates, 16 (80%) were resistant to oxacillin; 14 (70%) were resistant to amikacin and nalidixic acid; 12 (60%) were resistant to chloramphenicol and 11 (55%) were resistant to tetracycline. The L. monocytogenes isolates were 95%, 90% and 85% susceptible to amoxicillin, vancomycin, and clindamycin, respectively. All (100%) Listeria monocytogenes isolates were resistant for two or more drugs. Nineteen (95%) L. monocytogenes isolates were multidrug-resistant. One isolate (5%) had developed resistance to 10 classes of antimicrobial drugs.
Conclusions

Listeria species are widespread in the study areas. The study towns, season and working hours per day are independent predictors of Listeria species isolation. Multidrug resistance among L. monocytogenes is common. Therefore, regular training for meat handlers, prudent use of drugs, and further serological and molecular studies on Listeria species are important.