Improving environmental hygiene reduces HCAI: but which monitoring method is most effective?

A superb cluster randomised trial has just been published in Clinical Infectious Diseases testing whether improved environmental hygiene via objective monitoring and feedback reduces HCAI. The study also tests whether ATP or UV fluorescent marker monitoring is more effective. The findings reinforce that improving environmental hygiene reduces HCAI, and (I think surprisingly) suggest that ATP is more effective than UV monitoring.

This cluster RCT was undertaken in 6 ICUs in 3 US hospitals. Each unit received a period of UV fluorescent marker and ATP evaluation of cleaning effectiveness, in a randomised order with a washout period in between. A retrospective 12 month period before the interventions was used as a baseline period. Importantly, the UV or ATP assessments were undertaken by study staff, and hospital environmental hygiene staff were not notified when they would happen. So, limited prospects for “gaming the system”, which has been observed previously with the UV method. Results of the evaluation were reported back immediately to local staff, and surfaces recleaned if needed. There was also a weekly monitoring report sent to managers. The combined rate of infection or colonization with target HCAI organisms (C. difficile, MDR Gram-negatives, MRSA, and VRE) was the primary outcome. Infection rate (excluding colonisation) was a secondary outcome.

The rate of infection or colonisation was significantly lower in the ATP monitoring period compared with the UV monitoring period. Also, the rate of infection or colonisation was significantly lower for the ATP monitoring period compared with baseline, whereas this was not the case for UV. Interestingly, the overall fair rate was lower for ATP – but was proportionally higher for patient care objects than for room objects compared with UV. In addition, there was a significant correlation between ATP cleaning fails and HCAI, but not so for UV. Other possible confounders (such as antimicrobial consumption) were looked at and didn’t explain the difference. So, on the face of it, this seems to suggest that ATP is more effective than UV at focusing environmental hygiene activities on the surfaces that matter most.

However, there is an alternative explanation. As it happened, 4/6 units were randomised first to UV and then to ATP, and there was quite a “lead in” time for the hygiene fails (according to the UV method) to come down (as has been seen in other studies). See Figure 1 below. Could it be that the intervention had a cumulative effect and that the randomisation order favoured the ATP method by coming second most of the time? The comparison with the baseline period may also have been influenced by randomisation order. I did take a quick look at the corresponding trends of HCAI rates by time and unit in the supplementary data and the picture there wasn’t so clear. Also, the study team did a good job of trying to control for this statistically, and randomisation order was not associated with HCAI rate. But even so, it’s possible that this could have played a role.

Figure 1: Rate of hygiene fails by monitoring method and unit, over time.

Overall I really enjoyed reading this study, and hope you will find time to do the same. The findings reinforce that improved environmental hygiene reduces HCAI – easy to forget that this simple fact was disputed hotly not so long ago. The study goes further and suggests that ATP monitoring is more effective than UV monitoring when it comes to clinical outcomes. Whilst I hate to say it after reading a well planned RCT, I think we could do with a bit more comparative effectiveness data before we conclude categorically that ATP is superior to UV – but it’s looking that way from this study.


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