Quorum sensing in veterinary pathogens: mechanisms, clinical importance and future perspectives.

Under certain circumstances the individuals of a bacterial population may find advantages in acting together and making "collective decisions". This phenomenon is better known as quorum sensing. When the concentration of signal molecules produced by the surrounding bacteria exceeds a certain threshold, the bacterial population acts as a single organism, collectively expressing virulence genes, biofilm forming genes, etc. Several mechanisms of quorum sensing are discussed, each with its distinct signal molecules and respective receptors. Some of these mechanisms are restricted to sensing intraspecies signalling, but interspecies and even interkingdom signalling have also been described. Several veterinary pathogens such as Staphylococcus aureus, Staphylococcus pseudintermedius, Pseudomonas aeruginosa and Salmonella Typhimurium use quorum sensing as a means to optimize virulence gene expression and host colonization. Therefore, targeting of the QS mechanisms may provide a novel strategy for combating bacterial infections, also in veterinary medicine.