Antibiotic susceptibility patterns and plasmid profile of microbial isolates from vegetables collected in selected local market at Jimma town, southwest Ethiopia.

Abstract

Background: Vegetables can be contaminated with a range of microbial contaminants and pathogens and have long been known to serve as vehicles for transmission of infectious microorganisms Thus, this study was aimed to assess antibiotic susceptibility patterns and plasmid profile of microbial isolates from fresh vegetables collected in selected local market at Jimma town, southwest Ethiopia from Feb to April, 2015. Methods: A cross sectional study design was employed. A total of 150 fresh vegetable samples were purchased in different days from different outlets in Jimma town, from open market and groceries between Feb-April 2015. Equal numbers of vegetable types comprising lettuce, cabbage, carrot, tomato, green pepper, was purchased from farmers and four purposively selected local markets. For microbiological analyses, 25g of sample was aseptically weighed and washed in 225ml of sterile 0.1% (w/v) bacteriological peptone water (Oxoid) for 3 minutes. Appropriate serial dilutions of the suspension were plated on nutrient agar medium. Total plate count and pathogens isolation was done. Antimicrobial susceptibilities test and plasmid profile was performed. Results: More than 80% of vegetable samples had total viable counts of greater than106CFU/g with ranges of 105-107CFU/g. A total of 102 bacterial isolates of eight genera were identified. Enterobacter spp. (21.60%) was the most dominant followed by Citrobacter spp. (20.6%), Klebsiella spp. (18.6%), Salmonella spp. (11.8%), E. coli (10.8%), Proteus spp. (9.8%), Staphylococcus spp. (4.9%), and Pseudomonas aeruginosa (2%). Ampicillin and amoxicillin were highly resisted by more than 89% of microbial isolates. All the five S. aureus isolates were sensitive to oxacillin and vancomycin but two isolates were intermediately sensitive to erythromycin. Ciprofloxacillin was the least resisted drugs only 3.9 % whereas oxytetracycline was resisted by 31.4 % of the isolates. Resistance to nitrofurantoin, nalidic acid, streptomycin, chloramphenicol, cotrimoxazole, ceftriaxone, kanamycin and Gentamycin were 30.4%, 26.5%, 18.6%, 12.7%, 10.8%, 10.8%, 7.8%, 4.9% respectively. Plasmid was detected in 20 out of 91resistant isolate to at least one antibiotic. Conclusion and Recommendation: - Occurrence of antimicrobial resistance and plasmid carriage in bacterial populations in fresh vegetables at retails may constitute threats to consumers, possibly via resistance transfer. Thus, these results suggest the necessity to follow the hygienic practices in handling the vegetables.