Wow, it’s been ages since I’ve posted – sorry about that. I’m blaming the Omicron wave and my own personal dose of COVID-19 recently (you can see my reflections about that on Twitter…)

We have had #covid19 in Otter household (hence the quieter than usual twitter feed!). It's 2 weeks today since I tested positive so thought I'd share some reflections…

— Jon Otter (@jonotter) March 22, 2022

And so to today’s blog. Lots of interest in air disinfection systems. And some important research articles coming through. This one in JHI caught my attention, because there’s a suggestion of a link between improved air hygiene and reduced HCAI. However, I am unconvinced (from this study) that this link has been demonstrated – so a key opportunity for applied research!

This Turkish intervention cross-over study tested the impact of introducing a stand-along air disinfection system into two comparably sized 8-bedded critical care units. The air disinfection system used in this study combined HEPA filtration with plasma air disinfection to capture and/or inactive microbes in the air. A total of three units were placed in the first ICU, operated for 2 months with microbiological testing of air and surfaces, a 1 month washout period, and then the units were moved to the second ICU.

Whilst air and surface counts fluctuated, as you would expect, there seemed to be an overall reduction in the colony counts from air and surfaces in the intervention vs. the control ICU. Quite a few pathogens associated with HCAI were identified on air and surface samples from both units in all study phases. Rather shockingly, all A. baumannii and K. pneumonaie were resistant to carbapenems, and one K. pneumoniae was also resistant to colistin! There was a significant correlation between colony counts and the rate of HCAI in both the intervention and control ICUs. However, the study didn’t nail that the intervention was temporarily linked with a reduction in HCAI.

The study was limited by the fairly small size of the units chosen for the evaluation, and the short study duration. This resulted in natural fluctuations in colony counts and HCAI rates, and made the study difficult to interpret.

Overall, these findings are promising, and should lead to large studies with a more optimal design to evaluate a potential link between improvements in air hygiene and HCAI rates.