Comparison between adenosine triphosphate bioluminescence and aerobic colony count to assess surface sanitation in the hospital environment

Background The measurement of the bioluminescence produced by the firefly luciferase in the presence of adenosine triphosphate has been successfully introduced as a verification of the cleaning procedures according to the Hazard Analysis Critical Control Point system in the food industry. Our aim was to to evaluate the reliability of bioluminescence as a tool to monitor the effectiveness of sanitation in the hospital settings and to predict risk of healthcare associated infections, in  comparison with the microbiological gold standard assay. Methods 614 surfaces were randomly sampled in all hospital units to detect adenosine triphosphate bioluminescence and aerobic colony count. Statystical analysis relied on linear regression model and the calculation of Pearson correlation coefficient. Results Aerobic colony count had median values of 1.71 Colony Forming Units/cm 2 (interquartile range = 3.8), whereas adenosine triphosphate median was 59.9 Relative Light Units/cm 2 (interquartile range = 128.3). Pearson coefficient R 2 was 0.09. Sensitivity and specificity of bioluminescence test with respect to microbiology were 46% and 71%, whereas positive predictive value and negative predictive value were 53% and 65%, respectively. Conclusion According to our results, there seemed to be no linear correlation between aerobic colony count and adenosine triphosphate values, suggesting that the use of bioluminescence alone as predictor of infection risk is not sufficiently reliable.