In vitro antibacterial activity and synergetic effect of crude extract of the Wohlfahrtia nuba (Diptera: Sarcophagidae) flesh fly larvae

Abstract

Multidrug-resistant pathogens have become ubiquitous, and effective treatment alternatives are urgently required. Maggot therapy is a promising agent that is being studied to overcome antibiotic-resistant pathogens. This study evaluated the antibacterial activity of the larvae extract of the Wohlfahrtia nuba (wiedmann) (Diptera: Sarcophagidae) flesh fly on the growth 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]) in vitro by using different techniques. Resazurin-based turbidimetric assay demonstrated that the W. nuba maggot exosecretion (ES) was potent against all the bacterial species tested, and according to the determined minimum inhibitory concentration (MIC) for each bacterium, gram-negative bacteria were more sensitive than gram-positive bacteria. Additionally, colony-forming unit assay showed that maggot ES was able to inhibit bacterial growth rate for all bacterial species tested, where the highest bacterial reduction was observed with methicillin-sensitive S. aureus (MSSA) followed by S. typhi. Moreover, maggot ES was shown to be concentration-dependent, where 100 μL of ES at 200 mg/mL was bactericidal towards methicillin-resistant S. aureus (MRSA) and P. aeruginosa compared with 100 μL at the MIC of the ES. Moreover, based on the result of agar disc diffusion assay, maggot extract was more efficient against P. aeruginosa and E. coli than the remaining reference strains tested. Furthermore, the combination between regular antibiotics with maggot ES at different concentrations indicated that ES acts synergistically with the tested antibiotics against the five bacterial models.