Efficient Inactivation of Multi-Antibiotics Resistant Nosocomial Enterococci by Purified Hiracin Bacteriocin

Purpose: Because of the emergence of multi-antibiotic resistant bacteria, a number of infectious diseases have become a major concern to treat in health care services worldwide. This situation is worsened by the fact that very limited progress has been made in developing new and potent antibiotics in recent years. In this context antimicrobial peptides (AMPs) represent new potential therapeutic compounds with bactericidal or bacteriostatic activity against closely related bacterial strains. Methods: In this study, a collection of enterococci (n=170) from clinical sources were investigated for their potential to inhibit multiresistant nosocomial enterococci from Iranian hospitals. Results: Four isolates produced antimicrobial peptides that inhibited all the antibiotic resistant enterococci. This included three Enterococcus faecium isolates producing combinations of enterocin A, B and L50 AB. The most potent antagonism was produced by E. faecalis HO91. Purification and subsequent characterization by MALDI-TOF MS, Edman degradation and DNA-sequencing revealed that the antimicrobial compound was Hiracin. The purified Hiracin was evaluated for antibacterial activity against 12 multiresistant enterococcal isolates from clinical samples. The results demonstrated that Hiracin is highly effective towards enterococci which were resistant even to antibiotics from four distinct classes. Conclusion: The present research addresses Hiracin as a promising alternative to conventional antibiotics in treatment of multiresistant enterococcal infections.