Frequency of resistance and susceptible bacteria isolated from houseflies.

Background: In this study, we determine the vector competence of Musca domestica with reference to the transmission of susceptible and resistance bacterial strains in hospitals and slaughter house in Sanandaj City, west Iran.

Methods: Totally 908 houseflies were collected to isolate bacteria from their external body based on standard procedures.Antibiotic susceptibility testing was performed by Kirby-Bauer disc diffusion method on Mueller Hinton agar based on recommendations of CLSI (formerly the National Committee for Clinical Laboratory Standards).

Results: From collected houseflies, 366 bacteria species were isolated. The most common isolated bacterium at hospitals was Klebsiella pneumoniae 43.3% (n= 90) followed by Pseudomonas aeruginosa 37% (n= 77), while that of slaughterhouse was Proteus mirabilis. 29.1% (n= 46) followed by Citrobacter freundii 28.4% (n= 45). Among all the isolates from hospitals, cephalexin, chloramphenicol, ampicillin, and tetracycline, resistance rates were above 32.5% and gentamicin expressed the highest susceptibility among all the isolates from hospitals. It is worth to note that K. pneumoniae showed 61% and 44.5% resistance to cephalexin and chloramphenicol respectively. Similarly, all isolates from slaughterhouse were more than 28% and 30% resistant to cephalexin and chloramphenicol respectively. Surprisingly, among all the isolates, Citrobacter freundii were highly resistant to gentamicin.

Conclusion: Houseflies collected from hospitals and slaughterhouse may be involved in the spread of drug resistant bacteria and may increase the potential of human exposure to drug resistant bacteria.