Transmission from sink to patient: an evaluation of sink generated bioaerosols and their role in hospital acquired bacterial infections

Healthcare Associated Infections (HAIs) pose a significant public health risk. Hospital sinks and associated plumbing are one likely source. This study investigates bioaerosol emissions from sink P-traps during faucet operation to assess their potential role in pathogen transmission in the hospital context. We designed an aerosol chamber system with adjustable air change rate and a functioning sink meeting hospital standards. We quantified bioaerosol and large droplet emission factors from the sink, using F amp Escherichia coli as a model for Enterobacteriaceae such as Klebsiella pneumoniae . We cultured Andersen Cascade Impactor and BioSpot sampler aerosol samples and deposition plates using MI agar, which is selective for E. coli . Across five experiments, deposition plate counts were substantial, while air samples were close to detection limits. We estimated bioaerosol emissions factors of 1.3 x 10 -10 to 1.9 x 10 -10 CFU emitted per CFU in P-trap for aerosol particles less than 5.0 μm in diameter. The large droplet emission factor was one order of magnitude larger, at 4.3 x 10 -9 ± 2.8 x 10 -9 CFU per CFU. To demonstrate the application of the measured emissions data, we predicted Klebsiella pneumoniae inhalation dose (0.78 to 1.12 CFU day -1 ) and inhalation infection probability (∼10 -5 ) for 5.5 day hospital stay with colonized plumbing (air change rate 6 h -1 ). This translates to ∼1 infection per year for a hospital with a severe plumbing system colonization affecting ∼2000 continuously occupied rooms. For pathogens with different dose response curves, we demonstrate how infection probability via inhalation depends on dose response.