ATP determination as a method for assessing cleanliness is not applicable in hospital environments

Introduction: Several publications have reported a relation between nosocomial infections and the number of microorganisms in a hospital environment. ATP determinations are listed as a possible method for assessing hospital cleanliness. Objectives: To determine whether ATP determination as a marker of the microbial load can be used to assess level of hospital cleanliness compared to visual inspections and microbiological control. Methods: During one month four hospital rooms in an oncology ward were inspected using 1. Visual inspections according to Danish standards (DS-2451-10 and DS INSTA 800) 2. ATP determinations using 3 M" Clean-Trace" NGi Luminometer 3. Microbiological control using a TSI contact plate. Microbial load was determined by aerobic colony count and expressed as colony forming units per cm2 (CFU/cm2). All microorganisms were identified. The visual control and ATP determinations were made by the same supervisor. The cleaning staff was the same throughout the period. The microbiological control was performed by a microbiologist. Results: There is no consistency between the various techniques. There is a major difference between the two visual methods, and these are not concordant with ATP determinations. In only 70% of cases there is consistency between ATP measurements and microbiological control. Conclusions: ATP determinations cannot currently be recommended for controlling hospital cleanliness, because of the absence of sufficient correlation between this technique and microbiological controls. ATP determination may be useful as a method to identify surfaces which are difficult to clean.