Display Settings:

Format

Send to:

Choose Destination
We are sorry, but NCBI web applications do not support your browser and may not function properly. More information
Proc Natl Acad Sci U S A. 2006 Dec 19;103(51):19484-9. Epub 2006 Dec 5.

Antibiotics as intermicrobial signaling agents instead of weapons.

Author information

  • 1Departamento de Biotecnología Microbiana, Centro Nacional de Biotecnología, Darwin 3, Campus Universidad Autónoma de Madrid, Cantoblanco, 28049 Madrid, Spain.

Abstract

It has been widely assumed that the ecological function of antibiotics in nature is fighting against competitors. This made them a good example of the Darwinian struggle-for-life in the microbial world. Based on this idea, it also has been believed that antibiotics, even at subinhibitory concentrations, reduce virulence of bacterial pathogens. Herein, using a combination of genomic and functional assays, we demonstrate that specific antibiotics (namely tobramycin, tetracycline, and norfloxacin) at subinhibitory concentrations trigger expression of determinants influencing the virulence of the major opportunistic bacterial pathogen Pseudomonas aeruginosa. All three antibiotics induce biofilm formation; tobramycin increases bacterial motility, and tetracycline triggers expression of P. aeruginosa type III secretion system and consequently bacterial cytotoxicity. Besides their relevance in the infection process, those determinants are relevant for the ecological behavior of this bacterial species in natural, nonclinical environments, either by favoring colonization of surfaces (biofilm, motility) or for fighting against eukaryotic predators (cytotoxicity). Our results support the notion that antibiotics are not only bacterial weapons for fighting competitors but also signaling molecules that may regulate the homeostasis of microbial communities. At low concentrations, they can even be beneficial for the behavior of susceptible bacteria in natural environments. This is a complete change on our vision on the ecological function of antibiotics with clear implications both for the treatment of infectious diseases and for the understanding of the microbial relationships in the biosphere.

PMID:
17148599
[PubMed - indexed for MEDLINE]
PMCID:
PMC1682013
Free PMC Article

Images from this publication.See all images (2)Free text

Fig. 1.
Fig. 2.
PubMed Commons home

PubMed Commons

0 comments
How to join PubMed Commons

    Supplemental Content

    Icon for HighWire Icon for PubMed Central
    Loading ...
    Write to the Help Desk