Molecular characterization of multidrug-resistant bacteria isolated from the external and internal parts of the housefly

House flies are mechanical vectors of food borne enteric pathogenic bacteria which may transfer isolates to human and produce diseases. In Bangladesh, there is very limited data on molecular characterization of drug-resistant bacteria from isolated house flies. The research was conducted to determine the pathogenic bacteria isolated from houseflies in different location in Dinajpur district of Bangladesh and their antibiogram study for a period of one year from June, 2019 to July, 2020. A total of 140 houseflies were randomly collected and submitted to bacteriology lab, Hajee Mohammad Danesh Science and Technology University for microbiological analysis. A group of cultural tests, biochemical tests were used to isolation and identification of isolates and further confirmed through molecular characterization by the presence of 16S rRNA gene E1, E2 and invA. Additionally, 14 commercially available antibiotics were used by karby-bauer disk diffusion technique for antibiogram study. Results showed that the most commonly isolated bacteria from houseflies' external surfaces were Escherichia coli 19.04%, Salmonella typhimurium 15.87%, and Pseudomonas spp. 7.93% from 63 isolates, while 42 isolates found 35.71%, 28.57%, and 14.28% respectively. PCR amplification bands of Escherichia coli, Salmonella typhimurium, and Pseudomonas spp. were 584bp, 284bp, and 1497bp. Almost all the isolates were highly resistant to erythromycin, gentamycin, bacitracin (100%), followed by kanamycin, methicillin (80%) whereas highly sensitive to ciprofloxacin, chloramphenicol, azithromycin (100%), followed by tetracycline, amoxicillin (85.71%). These pathogenic microorganisms at distinct sampling sites indicate house flies may transmit vector-borne pathogens to humans. Based on these findings, we recommend vector-borne disease-fighting medications and a sustainable house fly-control approach. We also suggest promoting hygiene and food safety protocol to distance food ingredient from flies in local markets.