Comparing bacterial, fungal, and human cell concentrations with rapid adenosine triphosphate measurements for indicating microbial surface contamination

Abstract

The goal of this study was to test for associations between adenosine triphosphate (ATP) content and microbial concentrations on desk surfaces in school classrooms. ATP bioluminescence and quantitative polymerase chain reaction (qPCR) techniques were employed to measure total bacterial, fungal, and human cell concentrations on 66 high-traffic desks spread across 9 schools: 3 in Connecticut (CT) and 6 in Oklahoma (OK). In CT, 6 samples were taken from each desk, 1 precleaning and 5 postcleaning (after 30 minutes, 1 day, 3 days, 7 days, and 21 days). In OK, samples were taken immediately before and after cleaning each desk. Based on simple linear regression analyses, ATP values were good predictors of microbial concentrations (r = 0.8, P = .003) in both CT school postcleaning samples and OK pre- and postcleaning samples (r = 0.7, P = .00002). However, biomass reductions measured after cleaning were 1.5-2 times greater when measured by ATP than by qPCR (P = .007). Overall, ATP bioluminescence measurements correlate with qPCR-based surface measurements on school desks but may overestimate the physical removal of bacteria and fungi due to cleaning.