Molecular detection and antibiogram profiles of Escherichia coli and Vibrio cholerae isolated from raw vegetables in the northern district of Bangladesh

Raw vegetables are essential for a well-balanced diet as they provide vitamins, minerals, dietary fiber, and phytochemicals. This study aimed to isolate, identify, and evaluate the microbial loads of Escherichia coli and Vibrio cholerae in raw vegetables sold at local markets in the Dinajpur district of Bangladesh. A total of 35 vegetable samples were collected from four markets in Dinajpur district. The isolates were identified using cultural, staining, biochemical, and molecular tests. Microbial loads were enumerated (TVC) using the pour plate technique. Molecular detection of bacterial species was confirmed targeting the 16S rRNA and groEL genes of E. coli and V. cholerae, respectively. The amplification was done on 704 bp fragments of the 16S rRNA gene of E. coli and 1117 bp fragments of Vibrio spp. For the confirmation of V. cholerae, amplification of a 418 bp fragment of the groEL gene was performed through multiplex PCR. An antimicrobial susceptibility test was conducted on all isolates of bacteria against eleven and eight antibiotics by disc diffusion. The total viable count (TVC) in potato, carrot, cabbage, cauliflower, tomato, green chili, cucumber, mustard sak, and coriander leaves were 2.4 ± 0.37, 2.2±0.14, 2.1±0.26, 1.8±0.14, 1.7±0.27, 1.5±0.33, 1.5±0.33, and 1.4±0.25 mean log colony forming units ± standard deviation/mg, respectively. Out of 35 raw vegetable samples, 16 (45.71%) and 13 (37.14%) isolates were culture positive for E. coli and V. cholerae. Subsequently, 5 (31.25%) and 4 (30.76%) isolates of E. coli and V. choleraewere confirmed positive molecularly. All 16 and 13 isolates of E. coli and V. cholerae were subjected to antibiogram testing against 11 and 8 antibiotics. E. coli isolates were highly resistant to ceftazidime, cefixime, ampicillin, and oxytetracycline, but sensitive to gentamycin, ceftriaxone, colistin, and enrofloxacin. Similarly, V. cholerae isolates were highly resistant to nalidixic acid, trimethoprim, and polymyxin, but highly sensitive to kanamycin, gentamicin, and streptomycin. The study’s findings indicate that raw vegetables pose a significant public health risk due to MDR E. coli and V. cholerae. To achieve safer levels of these bacteria in raw vegetables, good production practices and hygiene awareness are essential.