This post follows hot on the heels of several other posts highlighting the potential benefits of water free care. A new retrospective cohort study in German ICUs has concluded that patients cared for in ICU single rooms or bays without sinks have fewer HCAI. Another nail in the coffin for sinks!

This multi-centre retrospective cohort study was based on a survey of German ICUs to identify which had sinks in patient rooms and which did not, and then compare HCAI outcomes from an established (and impressive!) national surveillance system. A total of 552 ICUs were included in the study, of which 80 didn’t have sinks in patient rooms / bays and 472 did. There were some differences in baseline characteristics between the two groups (i.e. sink vs. no sink). Units with no sinks in patient rooms / bays tended to be a bit smaller, more likely to be a tertiary referral centre, and a bit newer. All of these factors would feed into HCAI risk, particularly the tertiary referral aspects, with an expectation that tertiary referral centres would have patients with more co-morbidities and a higher underlying risk of HCAI.

In the multivariable analysis, the presence of a sink in a patient room, the type of ICU, the length of stay, ventilation, and urinary catheter were all associated with a significantly increased risk of HCAI. The adjusted incidence rate ratio of having a sink in the patient room was 1.21 (95% CI 1.01-1.45), meaning there was a 21% increase in infection risk associated with sinks. A range of HCAIs were significantly lower in rooms without a sink, including BSI, UTI, and lower respiratory tract infection caused by P. aeruginosa. Multivariable analyses identified sinks as a risk factor for BSIs and UTIs also (in addition to all HCAIs).

So, what’s going on here? Previous studies have explored whether going water-free reduces risks from either multidrug-resistant bacteria, or specifically from Pseudomonas. In the context of water-related Pseudomonas, and MDROs in general, exogenous transmission is recognised as the major player. However, received wisdom is that a large chunk of HCAIs originate from endogenous organisms. Therefore, is it biologically plausible for around 20% of HCAI to originate in micro-organisms from the sink? It’s an open question for me. I do think there is a significant confounding influence in this study – namely that there were more tertiary referral ICUs in the sink group, which creates some underlying imbalance in the system. The multivariable analysis went some way to control for this, but it’s a difficult thing to adequately control for underlying differences in case mix when looking at HCAI as an outcome.

For me, this study forms part of an ongoing narrative highlighting the risks from sinks and other water sources in the prevention and control of HCAI.