Muscoid Diptera as potential vectors of bacterial agents on dairy farms in the northern region of Paraná, Brazil

Abstract

The aim of this study was to determine the isolation frequency and microbial sensitivity profiles of Escherichia coli, Salmonella spp., and Staphylococcus spp. isolated from synanthropic flies captured in entomological traps placed near the milking parlors of 30 dairy farms located in Northern Parana, Brazil. In total, 192 flies were captured, and the isolation frequencies of muscids (21/30 = 70%) and califorids (27/30 = 90%) were significantly higher than that of sarcophagids (7/30 = 23.3%). Bacteriological tests on the internal contents and external surfaces of the flies showed that E. coli was present only in muscids (14.3%) and caliphorids (33.3%). Salmonella spp. was isolated from 9.5% of the muscids, 7.4% of the caliphorids, and 14.29% of the sarcophagids. Staphylococcus spp. was isolated from 28.5% of the muscids and 29.6% of the caliphorids. E. coli isolation was more frequent in flies captured on farms at which domestic chickens were housed near the milking parlors (p = 0.031) and which did not use sugarcane for animal feed (p = 0.042). Two out of 27 (7.4%) Staphylococcus spp. strains presented a phenotype of coagulase enzyme production. Ceftriaxone, ciprofloxacin, enrofloxacin, and gentamicin were the most effective antibiotics against E. coli and Salmonella spp. Tetracycline was the least effective antibiotic against the isolates. The Staphylococcus spp. strains isolated did not show the phenotype of oxacillin resistance. We conclude that regional flies are potential mechanical vectors of microbial agents able to cause enteritis in goats, mastitis in cows, and contamination of milk products for human consumption.