An intensive care unit outbreak with multi-drug-resistant Pseudomonas aeruginosa - spotlight on sinks.

BACKGROUND: Pseudomonas aeruginosa and other Gram-negative bacteria have the ability to persist in moist environments in healthcare settings, but their spread from these areas can result in outbreaks of healthcare-associated infections. METHODS: This study reports the investigation and containment of a multi-drug-resistant P. aeruginosa outbreak in three intensive care units of a Swiss university hospital. In total, 255 patients and 276 environmental samples were screened for the multi-drug-resistant P. aeruginosa outbreak strain. The environmental sampling and molecular characterization of patient and environmental strains, and control strategies implemented, including waterless patient care, are described. RESULTS: Between March and November 2019, the outbreak affected 29 patients. Environmental sampling detected the outbreak strain in nine samples of sink siphons of three different intensive care units with a common water sewage system, and on one gastroscope. Three weeks after replacement of the sink siphons, the outbreak strain re-grew in siphon-derived samples and newly affected patients were identified. The outbreak ceased after removal of all sinks in the proximity of patients and in medication preparation areas, and minimization of tap water use. Multi-locus sequence typing indicated clonality (sequence type 316) in 28/29 patient isolates and all 10 environmental samples. CONCLUSIONS: Sink removal combined with the introduction of waterless patient care terminated the multi-drug-resistant P. aeruginosa outbreak. Sinks in intensive care units may pose a risk for point source outbreaks with P. aeruginosa and other bacteria persisting in moist environments.

Eye-tracking to observe compliance with hand hygiene in the intensive care unit: a randomized feasibility study.

BACKGROUND: Healthcare-associated infections are associated with increased patient mortality. Hand hygiene is the most effective method to reduce these infections. Despite simplification of this easy intervention, compliance with hand disinfection remains low. Current assessment of hand hygiene is mainly based on observation by hygiene specialists. The aim of this study was to investigate additional benefits of eye-tracking during the analysis of hand hygiene compliance of healthcare professionals in the intensive care unit. METHODS: In a simulated, randomized crossover study conducted at the interdisciplinary intensive care unit at University Hospital Zurich, Switzerland, doctors and nurses underwent eye-tracking and completed two everyday tasks (injection of 10 µg norepinephrine via a central venous line, blood removal from the central line) in two scenarios where the locations of alcoholic dispensers differed ('in-sight' and 'out-of-sight'). The primary outcomes were dwell time, revisits, first fixation duration and average fixation duration on three areas of interest (central venous line, alcohol dispenser, protective glove box) for both scenarios. Compliance with hand hygiene guidelines was analysed. FINDINGS: Forty-nine participants (35 nurses, 14 doctors) were included in this study. Eye-tracking provided additional useful information compared with conventional observations. Dwell time, revisits, first fixation duration and average fixation duration did not differ between the two scenarios for all areas of interest. Overall compliance with recommended hand hygiene measures was low in both doctors (mean 20%) and nurses (mean 42.9%). CONCLUSION: Compared with conventional observations, eye-tracking offered additional helpful insights and provided an in-depth analysis of gaze patterns during the recording of hand hygiene compliance in the intensive care unit.

Protease-activated receptor-1 cleaved at R46 mediates cytoprotective effects.

BACKGROUND: Activated protein C (aPC) mediates powerful cytoprotective effects through the protease-activated receptor-1 (PAR1) that translate into reduced harm in mouse injury models. However, it remains elusive how aPC-activated PAR1 can mediate cytoprotective effects whereas thrombin activation does the opposite. OBJECTIVES: We hypothesized that aPC and thrombin might induce distinct active conformations in PAR1 causing opposing effects. METHODS: We analyzed antibody binding to, and cleavage and signalling of PAR1 in either endogenously expressing endothelial or overexpressing 293T cells. RESULTS: In thrombin-cleaved PAR1 neither the tethered ligand nor the hirudin-like domain were available for anti-PAR1 ATAP2 and WEDE15 binding unless the tethered ligand was quenched. In contrast, aPC irreversibly prevented ATAP2 binding while not affecting WEDE15 binding. Reporter constructs with selective glutamine substitutions confirmed R41 as the only thrombin cleavage site in PAR1, whereas aPC preferentially cleaved at R46. Similarly, we report distinct cleavage sites on PAR3, K38 for thrombin and R41 for aPC. A soluble peptide corresponding to R46-cleaved PAR1 enhanced the endothelial barrier function and reduced staurosporine toxicity in endothelial as well as in 293T cells if PAR1 was expressed. Overexpression of PAR1 variants demonstrated that cleavage at R46 but not R41 is required for cytoprotective aPC signaling. CONCLUSIONS: We provide a novel concept on how aPC and thrombin mediate distinct effects. We propose that the enzyme-specific cleavage sites induce specific conformations which mediate divergent downstream effects. This unexpected model of PAR1 signaling might lead to novel therapeutic options for the treatment of inflammatory diseases.

Coagulation factor Xa cleaves protease-activated receptor-1 and mediates signaling dependent on binding to the endothelial protein C receptor.

BACKGROUND AND OBJECTIVE: Coagulation is intrinsically tied to inflammation, and both proinflammatory and anti-inflammatory responses are modulated by coagulation protease signaling through protease-activated receptor-1 (PAR1). Activated factor X (FXa) can elicit cellular signaling through PAR1, but little is known about the role of cofactors in this pathway. Endothelial protein C receptor (EPCR) supports PAR1 signaling by the protein C pathway, and in the present study we tested whether EPCR mediates surface recruitment and signaling of FXa. METHODS AND RESULTS: Here, we show that FXa binds to overexpressed as well as native endothelial EPCR. PAR1 cleavage by FXa as analyzed with conformation-sensitive antibodies and a tagged PAR1 reporter construct was strongly enhanced if EPCR was available. Anti-EPCR failed to affect the tissue factor-dependent activation of FX, but high concentrations of FXa decreased EPCR-dependent protein C activation. Most importantly, the FXa-mediated induction of Erk1/2 activation, expression of the transcript for connective tissue growth factor and barrier protection in endothelial cells required binding to EPCR. CONCLUSIONS: Our results demonstrate that EPCR plays an unexpected role in supporting cell surface recruitment, PAR1 activation, and signaling by FXa.