Ventilator associated pneumonia (VAP), an usual nosocomial infection in
the intensive care units and the most common in mechanically ventilated
patients, is a serious problem due to high mortality and morbidity rates
associated. The presence of the endotracheal tube is the principal risk
factor for developing VAP because its surface is prone to microbial
adhesion and the formation of biofilms, deserving thus high attention in
clinical settings. Cell-to-cell communication is an important mechanism of
interaction between VAP microorganisms, being involved in the process
known as quorum-sensing (QS) that regulate the expression of virulence.
To evaluate bacteria fungi cross-talk in co-infection, the biofilm-forming
ability of Pseudomonas aeruginosa and Candida albicans, individually or
jointly, before and after antibiotic and antifungal co-treatment was tested.
Biofilms were characterized in terms of total mass and cell viability.
Results showed that no antimicrobial combination was successful in the
binary biofilms eradication. In some cases, the tolerance of the
polymicrobial consortia was higher than that of single biofilms,
highlighting that P. aeruginosa and C. albicans established synergistic
relationships. To gain knowledge helping to explain those interactions, a
quantitative real-time PCR approach was followed to inspect the
expression profiles of some cell-cell communication genes involved in
biofilm resistance. To overcome the tolerance issues, new antimicrobial
combinatorial approaches using QS-inhibitors are being tested. Some
combinations involving chlorogenic acid and ciprofloxacin displayed
promising anti-biofilm potential
