Major articleComparing visual inspection, aerobic colony counts, and adenosine triphosphate bioluminescence assay for evaluating surface cleanliness at a medical center

- Quantitative methods (aerobic colony count and adenosine triphosphate) are effective in evaluating hospital cleanliness.
- Adenosine triphosphate assay is rapid and sensitive when assessing the quality of hospital cleaning.
- The optimal cutoff adenosine triphosphate value to discriminate an aerobic colony count <2.5 colony forming units/cm2 is 5.57 relative light units/cm2.

BackgroundEnvironmental cleaning is essential in reducing microbial colonization and health care-associated infections in hospitals. However, there is no consensus for the standard method to assess hospital cleanliness, and comparisons of newer methodology, such as adenosine triphosphate bioluminescence assay, with the traditional methods are limited.MethodsA prospective study was conducted at a medical center between January 2013 and August 2013. In each selected room, 10-12 high-touch surfaces were sampled before and after terminal cleaning. The adequacy of cleaning was evaluated by visual inspection, aerobic colony counts (ACCs), and adenosine triphosphate (ATP) bioluminescence assay.ResultsEighty-five environmental surfaces from 8 rooms were evaluated by all 3 methods. The overall inadequacy defined by visual inspection, ACC, and ATP level was 11.8%, 20.0%, and 50.6% before cleaning and 4.7%, 5.9%, 21.2% after cleaning, respectively. A correlation between the ACC and ATP was found (r = 0.285, P < .001) using log10 values. Using ACCs <2.5 colony forming units/cm2 as the cutoff for cleanliness, the ATP assay had better sensitivity than visual inspection (63.6% vs 27.3%). The receiver operating characteristics of the ATP assay indicated that the optimal ATP cutoff value was estimated to be 5.57 relative light units/cm2.ConclusionATP bioluminescence assay is a sensitive and rapid tool in evaluating the quality of terminal cleaning. We emphasize the value of using a quantitative method to monitor environmental cleaning at hospitals.