Production of cell–cell signaling molecules by bacteria isolated from human chronic wounds

Abstract

Aim: To (i) identify chronic wound bacteria and to test their ability to produce acyl-homoserine-lactones (AHLs) and autoinducer-2 (AI-2) cell–cell signalling molecules and (ii) determine whether chronic wound debridement samples might contain these molecules. Methods and Results: Partial 16S rRNA gene sequencing revealed the identity of 46 chronic wound strains belonging to nine genera. Using bio-reporter assays, 69-6% of the chronic wound strains were inferred to produce AI-2, while 19-6% were inferred to produce AHL molecules. At least one strain from every genus, except those belonging to the genera Acinetobacter and Pseudomonas, were indicated to produce AI-2. Production of AI-2 in batch cultures was growth-phase dependent. Cross-feeding assays demonstrated that AHLs were produced by Acinetobacter spp., Pseudomonas aeruginosa and Serratia marcescens. Independent from studies of the bacterial species isolated from wounds, AHL and/or AI-2 signalling molecules were detected in 21 of 30 debridement samples of unknown microbial composition. Conclusion: Chronic wound bacteria produce cell–cell signalling molecules. Based on our findings, we hypothesize that resident species generally produce AI-2 molecules, and aggressive transient species associated with chronic wounds typically produce AHLs. Both these classes of cell–cell signals are indicated to be present in human chronic wounds. Significance and Impact of the Study: Interbacterial cell–cell signalling may be an important factor influencing wound development and if this is the case, the presence of AHLs and AI-2 could be used as a predictor of wound severity. Manipulation of cell–cell signalling may provide a novel strategy for improving wound healing.