Presentation Abstract

Abstract Title: Automobile Windshield Washer Fluid: a Novel Source of Exposure to Legionella
Author Block: D. O. Schwake, A. Alum, M. Abbaszadegan;
Arizona State Univ., Tempe, AZ
Keywords: legionella,pneumophila,automobile
Abstract: Legionellosis is a textbook example of a microbial disease inherently linked to not only the built environment, but also historically recent advances in man-made water distribution systems. Ubiquitious in natural fresh water, bacteria of the Legionella genus are capable of flourishing under conditions frequently generated in engineered water systems. While cooling tower vapor is often considered the primary source of human transmission for legionellosis, evidence for many other points of exposure related to the artificial environment has been reported, including automobiles. Epidemiological data suggesting driving automobiles as a risk factor for legionellosis prompted this study, with the goal of determining the potential for automobile windshield washer fluid to serve as a source of exposure for Legionella. To measure Legionella survival in washer fluid, Legionella pneumophila cultures were incubated in a variety of washer fluids. Legionella populations survived days to months depending on the washer fluid, with higher survival rates in one washer fluid when compared to sterile water. To determine the capability for Legionella growth in washer fluid reservoirs, reservoirs containing 1 L of L. pneumophila spiked or non-spiked tap water were incubated at room temperature and 37° C. Concentrations of Legionella increased over time for both inoculated and plain tap water at 37° C, with stable populations maintained for up to 14 months. Finally, a field study was conducted in central Arizona to detect and quantify Legionella in washer fluid collected from school buses. Culturable Legionella were isolated in approximately 75% of buses sampled, with L. pneumophila concentrations observed as high as 1.5 X 105 CFU/mL. Aerosolized cells were cultured from windshield wiper spray and seasonality was shown to have an impact on both positivity and concentration of culturable Legionella, both being lower in the winter. By demonstrating Legionella survival and growth in washer fluid reservoirs and documenting the presence of this pathogen in actual reservoirs, these results provide evidence suggesting this novel source of transmission, while simultaneously highlighting the potential for human-pathogen exposure in the relatively unexamined environment of automobiles.