The research team focused on Bahir Dar, the capital of the Amhara National Regional State, a city of roughly 565 kilometres from Addis Ababa that sits near Lake Tana and the headwaters of the Blue Nile. The city is a major tourist destination, perched on a plateau between 1,810 and 1,850 metres above sea level, with temperatures ranging from 10 to 38 degrees Celsius. Its meat trade operates through one municipal abattoir and approximately 91 licensed butcher houses, small privately owned establishments embedded in residential neighbourhoods, local markets, and busy streets. These shops typically display carcasses openly at ambient temperature so that customers and passers-by can inspect the meat, and cutting is performed manually with knives on wooden or plastic chopping blocks. Many also serve raw and cooked dishes on site, including kurt, thinly sliced raw beef eaten with hot pepper and mustard, and kitfo, minced raw meat blended with a chili-based spice mix and herb-infused clarified butter. These dishes, beloved across much of highland Ethiopia, mean that meat is frequently consumed without the thermal kill step that cooking provides, leaving any contamination intact when it reaches the diner’s plate.

Using Yamane’s sample size formula, the researchers randomly selected 74 of the city’s 91 licensed butcher houses, drawing their sampling frame from the Bahir Dar City Administration Municipal Office. Workers answered pre-tested structured questionnaires administered through interviews, and inspectors completed observation checklists during site visits. Samples of ready-to-eat raw meat, chopped with the knives normally used in the shops, were collected in sterile plastic bags and transported in ice boxes to the Amhara Public Health Institute Laboratory. In the laboratory, 25 grams of each minced sample were homogenized with 225 millilitres of buffered peptone water in a Stomacher 400 homogenizer, then plated onto Compact Dry EC medium, a chromogenic substrate on which E. coli forms distinctive blue to blue-purple colonies while other coliforms appear red or pink. Presumptive E. coli colonies were sub-cultured onto Sorbitol MacConkey agar, where the O157 serotype betrays itself by failing to ferment sorbitol, producing pale colonies rather than the pink colonies of ordinary strains. Confirmation proceeded through classical biochemical profiling, including triple sugar iron agar reactions, indole production, the methyl red test, and negative Voges-Proskauer and citrate results.

The headline finding was stark: 21 of the 74 samples, or 28.4 percent, were presumptively identified as E. coli O157:H7. This prevalence towers over figures reported elsewhere in Ethiopia, including 4.2 percent in Modjo and Bishoftu, 14.6 percent in Addis Ababa, 2 percent in Hawassa, and 4.5 percent in both central Ethiopia and Jimma town. It sits, however, below rates recorded in Nigeria at 53 percent, Bangladesh at 52.4 percent, and Argentina at 36.1 percent. The authors attribute the elevated Bahir Dar figure primarily to poor hygienic practice along the meat production chain, from slaughtering and transportation through to butcher-house handling, and note that differences in detection methods, sample sizes, and sampling approaches complicate direct comparisons between studies. Notably, the study did not use immunomagnetic separation, a technique that can improve detection sensitivity, meaning the true burden could conceivably be even higher.

What makes E. coli O157:H7 so feared is its arsenal of virulence factors, and the molecular portion of the study confirmed that the Bahir Dar isolates were not benign look-alikes. The pathogen’s disease-causing power rests on Shiga toxins 1 and 2, encoded by the stx1 and stx2 genes, on intimin, an attachment protein encoded by eaeA, and on enterohaemolysin, encoded by hlyA. In humans, infection can progress from watery diarrhoea to haemorrhagic colitis and, in the most severe cases, haemolytic uraemic syndrome, a life-threatening kidney condition. Crucially, the infectious dose of O157:H7 is extraordinarily low, meaning even a small amount of contaminated meat can cause illness. Because primers for some targets were unavailable, the team screened all 21 isolates by polymerase chain reaction for only two virulence markers, stx1 and eaeA. DNA was extracted using a boiling method, with colonies suspended in sterile distilled water, heated at 100 degrees Celsius for ten minutes, and centrifuged at 15,000 revolutions per minute; the supernatant then served as template. Amplification products were separated on 1.5 percent agarose gels stained with ethidium bromide and visualized under ultraviolet light, with sterile water and a known O157:H7 isolate serving as negative and positive controls.

Ten of the 21 isolates, or 47.6 percent, carried at least one of the two virulence genes investigated. Seven isolates carried both stx1 and eaeA, while three carried stx1 alone. The stx1 detection rate of 100 percent among gene-positive isolates exceeded figures reported from Saudi Arabia, where 45.45 percent of isolates carried the gene, and from India, where stx1 was found in 83.64 percent of beef isolates but eaeA in only 7.27 percent. The authors caution that the eleven isolates lacking these two genes cannot be declared harmless, since stx2 and hlyA were never assessed. Even so, the finding that roughly half of the contaminated retail meat samples harboured bacteria equipped with Shiga toxin and intimin genes establishes raw beef in Bahir Dar as a plausible vehicle for severe human infection, and a genuine public health concern rather than a merely theoretical one.

Perhaps the most actionable results came from the analysis of human behaviour. Logistic regression, with variables entering the multivariable model at a significance threshold of p less than 0.25, revealed two practices with strong statistical associations with contamination. Butchers who had received training in safe food handling had 84 percent lower odds of E. coli O157:H7 contamination in their meat than untrained colleagues, an adjusted odds ratio of 0.16 with a p-value of 0.028. Yet only 16.2 percent of the 74 workers had ever received such training, even though 81.1 percent had undergone health-status checks during employment. Conversely, workers who collected money from customers while cutting meat had 3.7 times higher odds of contamination than those who delegated cash handling to a separate collector, an adjusted odds ratio of 3.7 with a p-value of 0.047. At the time of the inspectors’ visits, 64.9 percent of workers were handling money and meat simultaneously, a practice higher than the 47.3 percent reported in a previous study. Banknotes, the authors note, are well-documented transmission media for microorganisms, and the hazard is acute when meat and money pass through the same unwashed hands.

Other observed habits fell short of international standards. Some 74.3 percent of workers wore jewellery such as rings and watches while processing meat, a figure consistent with the 78.9 percent reported in Mekele city, and only 32.4 percent used head covers and mouth masks. These practices run counter to the recommendations of the joint Food and Agriculture Organization and World Health Organization Codex Alimentarius Commission and to the Ethiopian Ministry of Agriculture, which advises that protective clothing such as gowns and hair covers be worn at all times when meat is handled. The workforce itself was overwhelmingly male, at 97.2 percent, and young, with 76 percent aged between 18 and 30, while 60 percent had more than three years of experience. Educational attainment ranged from no formal schooling for 4 percent of respondents to diplomas or higher for 9.4 percent, with just over half having completed only primary school.

On antimicrobial susceptibility, the news was comparatively encouraging. All 21 isolates were fully susceptible to gentamicin, ciprofloxacin, and kanamycin, while 86 percent were susceptible to ceftriaxone and 81 percent to chloramphenicol. Resistance was concentrated in older, widely used drugs: amoxicillin showed the highest resistance at 33.3 percent, followed by chloramphenicol at 28.6 percent, with six isolates resistant to two drugs and none to more than two. The authors attribute this pattern to inappropriate or excessive antibiotic use for therapeutic and prophylactic purposes in Ethiopian veterinary and human medicine, and warn that multidrug resistance, once established, severely hampers treatment of infections in both animals and people. The study’s limitations are acknowledged candidly: resources did not permit latex agglutination confirmation, serotyping, or sequencing, and reagent shortages prevented testing for stx2, hlyA, and resistance genes. Samples were also collected during 2019 and 2020, so the picture reflects that period. Nevertheless, the authors argue the findings provide a valuable baseline for Bahir Dar and a clear mandate: food safety training for butcher house owners and workers, routine surveillance, and further studies of additional virulence and resistance genes. In a city where raw beef is served as a delicacy, the difference between a safe meal and a dangerous one may come down to whether the person behind the counter has been trained, and whether they put down the knife before picking up the cash.

Subject of Research: Prevalence, virulence genes, antimicrobial susceptibility, and hygiene risk factors of Escherichia coli O157:H7 in raw retail meat in Bahir Dar City, Ethiopia

Article Title: Prevalence, Antimicrobial Susceptibility, and Hygienic Practices of Escherichia coli O157:H7 in Raw Meat, Bahir Dar City, Ethiopia

Article References: Asefa, W., Tassew, H., Bialfew, T., Gelaye, E., & Azene, B. T. (2026). Prevalence, Antimicrobial Susceptibility, and Hygienic Practices of Escherichia coli O157:H7 in Raw Meat, Bahir Dar City, Ethiopia. Veterinary Medicine and Science, 12(5), Article e71246. https://doi.org/10.1002/vms3.71246

Image Credits: AI Generated

DOI: 10.1002/vms3.71246

Keywords: Escherichia coli O157:H7, foodborne pathogens, raw meat, food safety, Ethiopia, Bahir Dar, Shiga toxin, virulence genes, antimicrobial resistance, butcher houses, hygiene practices, public health