Comparative antimicrobial activity of Moricin (naturally produced by silk worm, Bombyx mori larvae) against clinically important pathogens

With the emergence and spread of antimicrobial resistance (AMR) it becomes pertinent to search for an antimicrobial alternative to cater for the imminent need to control total drug-resistant (TDR) and multiple-drug-resistant (MDR) infections. Antimicrobial peptides (AMPs) have shown some promise and this study was designed to evaluate antimicrobial activity of Moricin (a naturally produced AMP by silkworm, Bombyx mori larvae) against 276 microbial strains of 83 species. Only two ( Erwinia amylovora 1, Hafnia alvei 1) strains were classified as susceptible to Moricin at a concentration ≤ 8 µg/mL. If susceptibility criteria were set at MIC equivalent to ≤ 128 µg/mL then Moricin inhibited 17 strains. All of the Bacillus species strains and majority of the strains of Acinetobacter , Aeromonas , Enterococcus , Erwinia , Raoultella , and Serratia species were significantly ( p < 0.05) more often resistant (MIC > 512 µg/mL) to Moricin than strains belonging to Alacligenes , Bacillus , Escherichia , Klebsiella , Pantoea , Pasteurella , Salmonella , Staphylococcus and Streptococcus species. Susceptibility of different bacteria not only varied significantly to Moricin but also to most of the commonly used antibiotics. The susceptibility of microbes not only affected by their type but also by their source of origin. The study concluded that Moricin has a wide spectrum but limited potential to inhibit clinically important microbial strains belonging to different species and genera.