BACTERIAL FAUNA ASSOCIATED WITH THE BLOW FLY, Chrysomya megacephala (F.) IN UBON RATCHATHANI PROVINCE OF NORTHEAST THAILAND

The objective of the current study was to isolate and identify the bacterial fauna associated with populations of the Oriental latrine fly, Chrysomya megacephala, collected in the Muang district of Ubon Ratchathani province, an area of high diarrhoeal disease incidence. A total of 294 flies were collected from September 2010-August 2011 using a sterilized insect sweep net at each collection site including fresh-food markets, garbage piles, restaurants, school cafeterias and paddy fields of Muang Ubon Ratchathani in the Ubon Ratchathani province. Each specimen was transferred into individual sterile glass vials for bacterial isolation using standard bacterial isolation techniques from the external surfaces of the flies of the 294 flies collected, 98.64% were found to be carrying multiple species of bacteria. A total of 15 bacterial genera were isolated, including both potentially pathogenic and non-pathogenic bacteria.The most common bacterium isolated from C. megacephala was coagulase-negative staphylococci (80.27%) followed by Streptococcus group D non-enterococci (69.05%). Among these were human pathogenic enteric bacteria including Escherichia coli O157:H7 (EHEC) and Salmonella typhi with the prevalence rates in flies being 3.06% and 20.88% respectively. Furthermore, other human pathogens were found such as Staphylococcus aureus and Pseudomonas aeruginosa. The present study demonstrates the potential of C. megacephala to vector pathogenic enteric bacteria to humans.