Viability of Pseudomonas aeruginosa in cough aerosols generated by persons with cystic fibrosis

Knibbs, Luke D; Johnson, Graham R; Kidd, Timothy J; Cheney, Joyce; Grimwood, Keith; Kattenbelt, Jacqueline A; O'Rourke, Peter K; Ramsay, Kay A; Sly, Peter D; Wainwright, Claire E; Wood, Michelle E; Morawska, Lidia; Bell, Scott C

A practical example of when to employ such models is when seeking to adhere to the US Centers for Disease Control and Prevention recommendation of allowing sufficient time for ≥99% removal of airborne contaminants following the departure of a patient with suspected or confirmed tuberculosis from a room before another patient enters. [16] Similarly, the model can help determine the time required to achieve a specified reduction in airborne P. aeruginosa in a CF clinic setting by taking into account the known room ventilation rate. Figure 3 in the paper shows that it would take approximately 50-min to achieve this removal, due to combined effect of ventilation and biological inactivation, in a clinic room ventilated at the guideline rate of two ACH. In addition to assuming that ventilation and biological decay are the major mechanisms which remove airborne P. aeruginosa from room air, we made two other key assumptions that underpin equation 1 and its use that affect the accuracy of our predictions. Firstly, and most importantly, the pathogen is assumed to be to be perfectly mixed with the room air, which is almost never the case in practice.