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Open Access Highly Accessed Research article

The two peptide lantibiotic lacticin 3147 acts synergistically with polymyxin to inhibit Gram negative bacteria

Lorraine A Draper1, Paul D Cotter23*, Colin Hill12* and R Paul Ross23

Author Affiliations

1 Department of Microbiology, University College Cork, Cork, Ireland

2 Alimentary Pharmabiotic Centre, University College Cork, Cork, Ireland

3 Teagasc Food Research Centre, Moorepark, Fermoy, County Cork, Ireland

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BMC Microbiology 2013, 13:212  doi:10.1186/1471-2180-13-212

Published: 26 September 2013

Abstract

Background

The emergence of bacterial drug resistance encourages the re-evaluation of the potential of existing antimicrobials. Lantibiotics are post-translationally modified, ribosomally synthesised antimicrobial peptides with a broad spectrum antimicrobial activity. Here, we focussed on expanding the potential of lacticin 3147, one of the most studied lantibiotics and one which possesses potent activity against a wide range of Gram positive species including many nosocomial pathogens. More specifically, our aim was to investigate if lacticin 3147 activity could be enhanced when combined with a range of different clinical antibiotics.

Results

Initial screening revealed that polymyxin B and polymyxin E (colistin) exhibited synergistic activity with lacticin 3147. Checkerboard assays were performed against a number of strains, including both Gram positive and Gram negative species. The resultant fractional inhibitory concentration (FIC) index values established that, while partial synergy was detected against Gram positive targets, synergy was obvious against Gram negative species, including Cronobacter and E. coli.

Conclusions

Combining lacticin 3147 with low levels of a polymyxin could provide a means of broadening target specificity of the lantibiotic, while also reducing polymyxin use due to the lower concentrations required as a result of synergy.

Keywords:
Antimicrobial; Synergy; Lantibiotic; Bacteriocin; Lacticin 3147; Polymyxin