Evaluation of the Antibacterial Activity of Chrysomya albiceps Larval Extract and its Synergistic Effects with Antibiotics

Abstract

Antimicrobial resistance is currently a significant global problem. The medical field is currently suffering from a shortage of effective treatments to prevent infections since the emergence rate of multidrug resistance has exceeded the rate of discovery and creation of new effective drugs. This study evaluates the antibacterial activity of the excretions/secretions of Egyptian calliphorid larvae, Chrysomya albiceps (C. albiceps), in vitro on the development of five pathogenic bacterial species (methicillin-sensitive Staphylococcus aureus ATCC 29213, methicillin-resistant Staphylococcus aureus ATCC BAA-1680, Pseudomonas aeruginosa ATCC 27853, Escherichia coli ATCC 25922 and Salmonella typhi ATCC 19430) via different assays. Resazurin-based 25turbidimetric assay (RTBA) proved that C. albiceps larval exosecretions (ES) was effective against all examined bacterial species, which also determined the minimum inhibitory concentration (MIC) for each bacterium. By using a colony-forming unit (CFU) assay, MICs of C. albiceps ES exhibited bacteriostatic activity against all tested bacteria. All the bacterial models could not recover after 24 hrs of the incubation period. However, high concentration (200 mg/ml) showed bactericidal activity towards P. aeruginosa. The potency of C. albiceps extract toward gram-negative bacteria has been proven by agar disc diffusion assay which failed to show any antibacterial efficiency of ES toward gram-positive bacteria. Synergism between larval ES and commercial antibiotics against all bacterial species was observed. The present data is promising and using these combinations can lead to a reduction in the minimum dose required for effective antimicrobial effects which is important because it may decrease both the risk of side effects and the costs of treatment of infectious diseases.