Assessment of microbiological quality and drug resistance patterns of raw vegetables irrigated with Hasassa River, West Arsi Zone, Oromia Region, Ethiopia

Irrigation scheme is among the major transmission modes of enteric human pathogens. Irrigation of vegetables with polluted water and untreated wastewater is a common practice worldwide. This practice is common in urban areas of low-income countries including Ethiopia, where there is increasing demands for fresh vegetables with poor wastewater treatment. The aim of the present study was to assess the microbial quality and prevalence of antimicrobial resistance of bacteria isolated from vegetables irrigated with Hasassa River, Southeastern Ethiopia. Irrigation water and vegetable samples (carrot, lettuce, and garlic) were collected from irrigation sites and analyzed for their bacteriological load and presence of any pathogenic microbes. The resistance patterns were detected following standard procedures. Appropriate serial dilutions of the suspension from 10-4, 10-5 and 10-6 were spread-plated on a suitable solid media for counts of aerobic Mesophilic bacteria, Gram-negative Enterobacteriaceae and Staphylococci, and homogenized samples were heated at 80°C for 10 min in a water bath to count aerobic spore formers, respectively. The maximum overall mean counts of aerobic Mesophilic bacteria, Enterobacteriaceae, aerobic spore formers, Staphylococci, and total coliform counts were 8.21, 6.58, 6,88, 6.88 log CFU ml-1 and >1100 MPN 100 ml-1, respectively. The microflora of vegetable samples were dominated by Bacillus species (21.9%) followed by Corynebacterium species (12.5%), Lactobacillus species (12.5%). Staphylococcus aureus and Salmonella species were detected in 21.9 and 15.6% of the samples, respectively. The result of antimicrobial test showed that all the isolates 32 (100%) were resistant to Penicillin, 26 (81.3%) to Vancomycin, 23 (71.9%) to Ampicillin, 15 (46.9%) to Chloramphenicol, 15 (46.9%) to Erythromycin, and the least 3 (9.4%) to Perfloxacin. The present finding revealed that vegetables irrigated with Hasassa River appears to pose microbial contamination which may be transferred directly or indirectly during pre-harvest and post-harvest handling to fresh vegetables which potentially constitutes a health risk to consumers.