Infections related to contaminated foods are major health problems, especially in developing countries, including Ethiopia. However, limited information were available on incidence and antimicrobials susceptibility pattern of the causative agents to helps policy makers to develop appropriate strategies in terms of prevention, treatment and control. In this study, different samples such as meat of cattle, ceacal content of slaughtered animals, swab samples taken from hands of meat handlers, and different surfaces that have contact with meat were tested for the presence of E. coli and E. coli O157: H7. Accordingly, E. coli were detected in 102 (20.2%) of the samples tested, whereas E. coli O157: H7 were detected in 27 (5.4%) of the samples. The proportion of positive samples in this study was higher than the previous study finding in different parts of Ethiopia [8, 14–20]. However, this study finding is lower than the study finding in Ethiopia and other country [9, 21, 22]. The observed differences might be due to the use of different methods of detections of isolates, differences in sample size, the type of sample and how and when it was collected. For instance, the use immuno-magnetic separation and PCR technique may improve the sensitivity of the detection, which was not done in this study methodology.
With regard to sample source, 55 (19.3%) and 17 (6.0%) of samples from abattoir house and 47 (21.4%) and 10 (3.7%) of samples from butcher shops were positive for E. coli and E. coli O157: H7, respectively. Despite of the differences in proportion of positive samples, the presence of E. coli and E. coli O157: H7 in abattoir and butcher shops samples were reported in many studies in Ethiopia [14–16, 20, 23–25]. The expected slight differences might be due to the difference in hygienic conditions that could be risky for cross-contamination of meat and different contact surfaces with fecal materials during slaughtering, processing, transportation, and displaying at abattoir house and retailer shops. At all these stages, strict adherence to standard operating measures must be practiced.
With regard to samples types, higher proportions of ceacal contents of slaughtered animals were positive for E. coli and E. coli O157: H7 followed by meat and other different swab samples obtained from abattoir and butcher shops. The presence of E. coli and E. coli O157: H7 in meat samples, ceacal content and swab samples were also reported in different studies in Ethiopia [9, 14–21, 23–27]. Many reasons might be contributed for cross- contaminations of meat and surface contacts with ceacal contents and other sources. Previous work in cattle suggests that the prevalence of E. coli O157:H7 in the feces is correlated to the prevalence on the hide and carcasses of animals at slaughter [28, 29]. In the present study, poor hygienic practices of abattoir house and butcher shops workers observed were found to be risky for contamination of meat with E. coli and E. coli O157: H7. This condition is more risky in our situation; because of the wide spread practice of raw meat consumption throughout the country. A studies concluded that, raw meat can harbor harmful pathogenic E. coli (E. coli O157: H7) organisms causing diarrhoea and systemic manifestations such as hemorrhagic colitis, hemolytic uremic syndrome (HUS) [30, 31].
Contamination of meat with faecal material in the slaughtering process and during displaying of meat for vendor is the main transmission route of bacteria. It is well documented facts that, lack of education and training on food safety may contribute for unhygienic practice such as improper handling, processing and display of meat at the slaughtering places and at butcher shops [16, 23–25, 32]. In this study, none of the abattoir and butcher shop workers have formal education certificate on food safety and short course training on safe meat handling. That is why; risky practices during the slaughtering, transportation and display of meat were observed and documented in the present study. For instance, neither abattoir workers nor butcher shop workers have had regular washing and disinfection practices of their hands, the floor and meat processing tools. In addition, none of them were didn’t use separate chopping boards and knives for cutting and removal of abdominal contents. At slaughter house, workers touch the soiled outside parts of the animal’s skin while removing the skin, can facilitate transfer of pathogens onto the sterile carcass surface. Thus, the presence of E. coli and E. coli O157:H7 on meat might be due to transfer of fecal material onto the carcass during the slaughter process or from different contaminated materials and hands of meat handlers. This may indicated with currently available dressing procedures at the abattoir house and further meat processing at butcher shops cannot be reliable to prevent fecal and cross-contamination of meat.
Moreover, workers at the slaughter house were not well supplied with materials that would enable them to maintain general hygiene. For instance, inadequate supply of clean water is one of the greatest challenges to maintain hygiene. The slaughtering processes were also done in the same area without separate dirty and clean zone, which poses risk conditions for cross- contamination of carcasses. In addition, the visceral organs were put very near to the carcass when displayed for sale or when meat cut into pieces for selling or consumption. Therefore, the range of activities should be carried out with the appropriate training on knowledge and hygienic practices of meat handlers.
In this study, antimicrobial resistance pattern of isolates were checked with different classes of antibiotics. Accordingly, a total of 98 (76.6%) E. coli and E. coli O157: H7 isolates were resistant to two or more classes of antibiotics. The prevalence of multi-drug resistant isolates was also reported in previous studies in Ethiopia [8, 14, 19, 20, 25, 33], in which about (33.2–100%) of isolates were showed multidrug resistance. The occurrence of multidrug resistance may be linked with indiscriminate utilization of antimicrobial agents or genetic mutation, which was not elucidate with the present study methodology. Moreover, transmission of multi-drug resistant bacteria via consumption of meat and meat products has been suggested as a potential source in Africa [34, 35].
In this study, third generation cephalosporin (cefotaxime, ceftriaxone and cefotaxime), gentamycin, ciprofloxacin, kanamycin, streptomycin and chloramphenicol showed best activities against our isolates. The best efficacies of the above antibiotics were also reported in previous study findings in Ethiopia with different resistance rate [14, 15, 17, 18, 25, 33]. In contrast, higher resistance was observed against erythromycin and ampicillin, followed by tetracycline, co-trimoxazole and amoxicillin -clavulanic acid. With the exception of tetracycline, co-trimoxazole and amoxicillin -clavulanic acid, higher were resistance against erythromycin and ampicillin were also reported the previous studies in Ethiopia [8, 17, 25, 26]. In some studies, (33.3–80%) of the isolates were resistant to amoxicillin-clavulanic acid, streptomycin, co-trimoxazole and tetracycline [8, 14, 15, 25, 33]. This might be due to inappropriate and excessive use of these antibiotics for therapeutic and prophylactic purpose both for E. coli and other infections. In fact, the frequent and miss-use of antibiotics in humans and food animal greatly linked to the recent emergence of multi-drug resistance bacteria. This situation may leads to increased load of antibiotics, poor clinical outcome and limited therapeutic options.