Abstract

The excessive usage of conventional antibiotics leads to the emergence of multidrug-resistant bacterial strains which threaten public health and stimulates searching for new sources of bio-therapeutic drugs. The aim of this study was to investigate the antimicrobial activity of maggot excretions/secretions from larvae of Sarcophaga argyrostoma, a common species of the family Sarcophagidae in Egypt. The excretions/secretions (ES) produced by third instar larvae were sterile filtered and tested against selected pathogenic strains of Gram positive (Gram+ve) bacteria, Staphylococcus aureus and Bacillus subtilis; Gram negative (Gram-ve) bacteria, Escherichia coli and Pseudomonous aeruginosa; and the filamentous fungus Aspergillus flavus. The ES product produced by third instar maggots proved to be more effective against Gram-ve bacteria. Larval ES, at 0.125 mg/ml concentration, were significantly potent towards P. aeruginosa, E. coli and S. aureus in a descending sequence. The minimum inhibitory concentrations of S. argyrostoma ES were 0.125 mg/ml for P. aeruginosa and E. coli, using the turbidimetric assay method. Twice and four times this concentration were required to inhibit growth of S. aureus (0.25 mg/ml) and B. subtilis (0.5 mg/ml), respectively. The antibacterial properties of S. argyrostoma ES were not affected by heating or freeze-thaw cycles when tested against E. coli.

Key words: Sarcophaga argyrostoma, antimicrobial activity, larval excretions, larval secretions, minimum inhibitory concentration.