Response to commentary on “Assessing risk of health care–acquired Legionnaires' disease from environmental sampling: The limits of using a strict percent positivity approach”

We appreciate the commentary from Pierre et al regarding our article published in the American Journal of Infection Control in 2012. One of our goals was to start a discourse on the utilization of 30% prevalence of Legionella in a hospital water system as a reliable decision point for determining the risk of Legionnaires' disease and subsequent interventions, and we welcome the opportunity to discuss this important issue further. As shown in our article, and will be further demonstrated in this response, this 30% cut-off has been adopted and referenced by various government agencies and peer-reviewed journal articles without critical evaluation since its emergence in 1983.