Bactericidal activity of Musca domestica cecropin (Mdc) on multidrug-resistant clinical isolate of Escherichia coli

Abstract

The housefly (Musca domestica) larvae have been used clinically to cure osteomyelitis, decubital necrosis, lip boil, ecthyma and malnutritional stagnation ever since the Ming/Qing Dynasty (1368 Anno Domini) till now, in China. In prior research, we have cloned and characterized a new gene of antimicrobial peptide cecropin from M. domestica larvae. This peptide was potently active against Gram-positive and Gram-negative bacteria standard strain. In the present study, we evaluated the possibility of Mdc to be a potential bactericidal agent against clinical isolates of multidrug-resistant (MDR) Escherichia coli and to elucidate the related antimicrobial mechanisms. Antimicrobial activity assays indicated a minimal inhibitory concentration (MIC) of 1.56 μM. Bactericidal kinetics at MIC showed that Mdc rapid killing of MDR E. coli. Lipopolysaccharide (LPS) dose-dependently suppressed Mdc antibacterial potency indicates that LPS is the initial binding site of Mdc in E. coli. Propidium iodide-based flow cytometry revealed that Mdc causes E. coli membrane permeabilization. Transmission electron micrographs further indicated that a remarkable damage in the bacteria's outer and inner membrane, even the leakage of cytoplasmic contents induced by Mdc. DNA binding experimental result implies that DNA is one of the possible intracellular targets of Mdc. Of note, Mdc did not show a perceptible cytotoxic effect on human red blood cells. Altogether, these results suggest that Mdc could be an excellent candidate for the development of more efficacious bactericidal agents.

Inflammatory Regulation Effect and Action Mechanism of Anti-Inflammatory Effective Parts of Housefly (Musca domestica) Larvae on Atherosclerosis

“…D) [4]. During the past decade, due to the antibacterial activity of housefly larvae and its products, they have been used mainly in preservation [11], environmental protection [12], and inhibition of multiresistant bacteria [13]. In recent years, several reports suggested that atherosclerosis is a chronic inflammatory disease [14, 15] that can be accelerated by microbial infection in its early phase [16, 17].…”

Transmission Electron Microscopic Morphological Study and Flow Cytometric Viability Assessment ofAcinetobacter baumanniiSusceptible toMusca domesticacecropin

“…Kinetics of bacterial killing was determined according to the method described in Lu et al [22]. Log-phase A. baumannii strains GIM1.650 (10 6  CFU/mL) were incubated with culture medium containing zero or MIC, 1/4 MIC Mdc for 120 min.…”

“…A limitation for the transition of cecropin to therapeutic purpose is the hemolytic or cytotoxicity properties [21]. Of important note, Mdc did not show a perceptible cytotoxic effect on human red blood cells [22]. So, it is a subject for further studies whether Mdc will be a novel and effective clinical alternative against the increasing threat of a widespread dissemination of multidrug-resistant A. baumannii .…”

Insects: an underrepresented resource for the discovery of biologically active natural products

“…They are also popular in Latin American medicine for boils, baldness, eyesores, external sebaceus lamps, stye, ophthalmological problems, dermatosis, cysties and erysipelas 12 . In China, the use of housefly larvae to cure osteomyelitis, decubital necrosis, lip boil, ecthyma and malnutrition stagnation dates back to the Ming/Qing Dynasty 145 .…”