Hospital environmental hygiene plays a central and decisive role in the emergence of Healthcare-Associated Infections (HAIs). The perception that environmental contamination contributes to this factor highlights the need to understand how the effectiveness of hygiene in intensive care unit (ICU) beds is associated with the incidence of HAIs among occupants.

This study analyzes, through an ecological study, the relationship between environmental cleaning and the occurrence of HAIs in ICU beds, associating environmental cleaning effectiveness with the incidence of HAIs in these spaces.

Using a chemiluminescent marking technique, an ecological study was conducted in three adult ICUs of a tertiary hospital between May and June 2025. A 20% alcoholic fluorescein suspension, easily removable by friction, was applied as markings invisible to the naked eye at strategic points (frequently touched areas and others that represent challenges to the process). The removal rate was considered as the ratio between removed points and the total evaluated—distinguishing cleaning under the responsibility of nursing staff from that performed by the hospital hygiene team—generating 95% confidence intervals using exact binomial distribution and comparing results using Clopper–Pearson tests. Finally, the point removal rate was correlated with the cumulative incidence of HAIs (VAP, PBSI, UTI, and SSI) per bed using Pearson’s test.

When associating HAIs with bed hygiene, an Odds Ratio (OR) of 1.29 with a confidence interval (CI) of 1.03–2.11 (p = 0.04) was found, with variation of up to 30% in cleaning rates of occupied beds depending on the day, professional responsible for cleaning, and ICU. In mixed-effects multivariate analysis, including a random intercept for bed type (standard or under special precautions) and collection unit, beds with cleaning effectiveness below 80% were independently and statistically significantly associated with a 29% increase in the odds of developing HAIs.

Adequate environmental hygiene is a determining factor in preventing HAIs, especially in ICUs. Even small inconsistencies in the protocol can have clinical repercussions for patients.