How clean is clean? Proposed methods for hospital cleaning assessment

Abstract

Reducing infection rates in hospitals depends on a variety of factors, including environmental measures. Although microbiological standards have been proposed for surface hygiene in hospitals, standard methods for environmental sampling have not been discussed. The aim of this study was to assess the effectiveness of cleaning/disinfection in critical care units using the wipe-rinse method to detect an indicator organism and dipslides to quantitatively determine the microbial load. Frequent-hand-touch surfaces from clinical and non-clinical areas were microbiologically surveyed, targeting both meticillin-susceptible (MSSA) and meticillin-resistant (MRSA) Staphylococcus aureus. A subset of the surfaces targeted was sampled quantitatively to determine the total aerobic count. MRSA was isolated from 9 (6.9%) and MSSA was isolated from 15 (11.5%) of the 130 samples collected. Seven of 81 (8.6%) samples collected from non-clinical areas grew MRSA, compared with two (4.1%) from 49 samples collected from clinical areas. Of 116 sites screened for the total aerobic count, 9 (7.7%) showed >5 cfu/cm(2) microbial growth. Bed frames, telephones and computer keyboards were among the surfaces that yielded a high total viable count. There was no direct correlation between the findings of total aerobic count and MRSA isolation. We suggest, however, that combining both standards will give a more effective method of assessing the efficacy of cleaning/disinfection strategy. Further work is required to evaluate and refine these standards in order to assess the frequency of cleaning required for a particular area, or for changing the protocol or materials used.