Pseudomonas aeruginosa bioflm formation on endotracheal tubes requires multiple two-component systems

Introduction. Indwelling medical devices such as endotracheal tubes (ETTs), urinary catheters, vascular access devices, tra-cheostomies and feeding tubes are often associated with hospital- A cquired infections. Bacterial bioflm formed on the ETTs in intubated patients is a signifcant risk factor associated with ventilator- A ssociated pneumonia. Pseudomonas aeruginosa is one of the four frequently encountered bacteria responsible for causing pneumonia, and the bioflm formation on ETTs. However, understanding of bioflm formation on ETT and interventions to prevent bioflm remains lagging. The ability to sense and adapt to external cues contributes to their success. Thus, the bioflm formation is likely to be infuenced by the two-component systems (TCSs) that are composed of a membrane- A ssociated sensor kinase and an intracellular response regulator. 

Aim. This study aims to establish an in vitro method to analyse the P. aeruginosa bioflm formation on ETTs, and identify the TCSs that contribute to this process. Methodology. In total, 112 P. aeruginosa PA14 TCS mutants were tested for their ability to form bioflm on ETTs, their efect on quorum sensing (QS) and motility. Results. Out of 112 TCS mutants studied, 56 had altered bioflm biomass on ETTs. Although the bioflm formation on ETTs is QS-dependent, none of the 56 loci controlled quorum signal. Of these, 18 novel TCSs specifc to ETT bioflm were identifed, namely, AauS, AgtS, ColR, CopS, CprR, NasT, KdpD, ParS, PmrB, PprA, PvrS, RcsC, PA14_11120, PA14_32580, PA14_45880, PA14_49420, PA14_52240, PA14_70790. The set of 56 included the GacS network, TCS proteins involved in fmbriae synthesis, TCS proteins involved in antimicrobial peptide resistance, and surface-sensing. Additionally, several of the TCS-encoding genes involved in bioflm formation on ETTs were found to be linked to fagellum-dependent swimming motility. Conclusions. Our study established an in vitro method for studying P. aeruginosa bioflm formation on the ETT surfaces. We also identifed novel ETT-specifc TCSs that could serve as targets to prevent bioflm formation on indwelling devices frequently used in clinical settings.