Are hygiene standards useful in assessing infection risk?

Abstract

Background: We monitored the surface level cleanliness in a 5-bed surgical intensive care unit (SICU) over a 10-week period to evaluate proposed hygiene standards.

Methods: Ten environmental sites within the SICU were sampled twice weekly, along with collection of clinical and patient activity data. The standards designate aerobic colony counts (ACCs) > 2.5 colony-forming units/cm(2) from hand-touch sites and the presence of Staphylococcus aureus as indicating hygiene failure.

Results: Nearly 25% of the 200 samples analyzed did not meet the standards, mostly from hand-touch sites on curtains, beds, and medical equipment. The total number of failures each week was associated with bed occupancy (P = .04), with a trend toward association with SICU-acquired infection (P = .11). Environmental S aureus was associated with the proportion of beds occupied (P = .02). Indistinguishable genotypes were found between patient and environmental staphylococci, with time scales supporting staphylococcal transmission in both directions.

Conclusions: Hygiene standards based on microbial growth levels and the presence of S aureus reflect patient activity and provide a means to risk-manage infection. They also expose a staphylococcal reservoir that could represent a more tangible risk to patients. Standards for surface level cleanliness merit further evaluation.