Antibiotic Resistance Patterns of Enterococcus spp. Isolated from Musca domestica and Chrysomya megacephala in Ubon Ratchathani
Tarinee Chaiwong PhD*, Thanyakarn Srivoramas MSc*, Marutpong Panya PhD*, Surasak Wanram PhD*, Pawana Panomket PhD*
Affiliation : * College of Medicine and Public Health, Ubon Ratchathani University, Ubon Ratchathani, Thailand
Background : The housefly Musca domestica and the blowfly Chrysomya megacephala are found worldwide and are medically
significant as mechanical vectors of various pathogens from unsanitary locations to food, resulting in diseases in humans.
Objectives: This study aimed to test the antimicrobial activity against Enterococcus spp. isolated from M. domestica and C.
megacephala by standard disk diffusion and minimal inhibitory concentration (MIC), and to study the potential of M.
domestica and C. megacephala to transfer multi-drug resistant enterococcus to humans.
Material and Method: Seven hundred adult flies were collected from fresh-food markets, garbage piles, restaurants, school
cafeterias, and rice paddy fields in Muang Ubon Ratchathani and Warinchamrap in Ubon Ratchathani Province. Antimicrobial
susceptibility for Enterococcus spp. isolated from adult flies was performed by disk diffusion test and minimum inhibitory
concentration (MIC) determination.
Results : One hundred and twenty isolates of Enterococcus spp. were taken from 67 M. domestica and 53 C. megacephala.
Standard disk diffusion showed the Enterococcus spp. isolates exhibited susceptibility to ampilcillin (99.2%), chloramphenicol
(74.2%), tetracycline (75.0%), vancomycin (50.8%), and erythromycin (42.5%). The MICs of antimicrobial agents for all
isolates were <0.25-8 μg/mL for vancomycin, 1->16 μg/mL for tetracycline, 4->16 μg/mL for chloramphenicol, and 0.5-8
μg/mL for ciprofloxacin.
Conclusion : The study demonstrated the potential of M. domestica and C. megacephala to carry Enterococcus spp. Nine anti-
microbial susceptibility patterns were obtained among the 120 enterococci isolates.
Keywords : Enterococcus spp., Musca domestica, Chrysomya megacephala
