Antibacterial activity of house fly-maggot extracts against MRSA (Methicillin-resistant Staphylococcus aureus) and VRE (Vancomycin-resistant enterococci)

The principal objective of this study was to determine the in vitro antibacterial activity of the water-soluble protein enzymatic hydrolysates and the ethanol (EtOH)-extracted fraction obtained from fly-maggots (Musca domestica L.) against MRSA (methicillinresistant Staphylococcus aureus) strains and VRE (Vancomycin-resistant enterococci) 5117 strain. The water soluble protein enzymatic hydrolysates were prepared via 4 or 8 hr of incubation after mixing with the water-soluble protein extracted from the fly-maggots plus thermolysin. The EtOH-extracts A was prepared by homogenizing after mixing with the fly-maggots plus pure EtOH at room temperature. The EtOH-extracts B and C was obtained via filtering after stationing for 24 hr at 4-20C using the EtOH-extracts A, respectively. The growth inhibition curves for MRSA strain 3595 and VRE strain 5117 in the water-soluble protein enzymatic hydrolysates were increased and evidenced concentration-dependent inhibition in the 8-hr hydrolysate as compared with the 4-hr hydrolysate (p<0.05). The growth inhibition curves for MRSA and VRE strains in the EtOH-extracted fraction obtained from the fly-maggots were high in EtOH-extract C as compared with EtOH-extracts A and B (p<0.05). The minimum inhibitory concentrations (MIC) in the EtOH-extracts C, in which the growth inhibition of MRSA and VRE strains was increased, were determined to be 40, 50, 50, 60, 40 and 60 μg ml in MRSA strains 3598, 3595, 3601, 3589, 3597 and 3595, respectively. While the butanol fraction obtained from EtOH extract C evidenced profound antibacterial activity against the MRSA and VRE strains, the antibacterial activity of the hexane, ethyl acetate, and water layers could not be adequately confirmed.