Bacteriocin production by clinical isolates of ‘Non fermenting Gram negative bacilli’- a ray of hope in the post antibiotic era

Abstract

Background: Bacteriocins are a kind of ribosomal synthesized antimicrobial peptides produced by bacteria, during their growth, triggered by competition for space and scarce resources. Non fermenting Gram negative bacilli (NFGNB), which have pivotal role in causing health care associated infection (HAI) need to establish themselves in the hospital environment pushing aside existing flora and do so probably by bacteriocin production.Objective:Present study was undertaken to explore bacteriocin production ability of Pseudomonas aeruginosa and Acinetobacter baumannii and their range of action on other bacteria.Setting and design: A prospective observational study.Material and methods:Fifty MDR-NFGNB isolates were tested for phenotypic detection of bacteriocin production against commonly encountered indicator hospital strains and control strains following some modification of Gratia and Fredericq’s method.Results: All 27 (100%) Pseudomonas aeruginosa isolates, produced bacteriocin active against Escherichia coli and Klebsiella pneumoniae, 26(96.2%) and 21(77.7%) acted on Proteus mirabilis and Enterococcus faecalis respectively. Out of 23 Acinetobacter baumannii, 20(86.9%), 15(65.2%), 15(65.2%) and 12(52.1%) produced bacteriocin active against Enterococcus faecalis, Escherichia coli, Coagulase negative Staphylococcus species (CoNS) and Klebsiella pneumonia respectively. Bacteriocin produced by A baumannii had similar effect on both Gram positive and Gram negative bacteria.Conclusion: The antibacterial spectra of these bacteriocins raise a hope of using these peptides therapeutically in post-antibiotic era.