Enumeration and characterization of five pathogenic Legionellaspecies from large research and educational buildingsElectronic supplementary information (ESI) available. See DOI: 10.1039/d0ew00893a

Legionella pneumophilais the species that is most often cultured from the natural environment, while disease-relevant Legionellaspecies, such as Legionella micdadei, Legionella bozemanii, Legionella anisa, and Legionella longbeachaehave yet to be extensively explored in premise plumbing systems. This study examined the concentrations of five pathogenic Legionellaspecies (listed previously) in the influent and the taps of five different large buildings (BPS, ERC, F, FH, and M), undertaken during the start of two semesters (late summer/fall (August–September) and early winter/spring (January)). A total of 37 large-volume samples to examine building water quality (influents to the buildings and exposure sites (taps)) were collected and analyzed using droplet digital™ PCR. Legionellaspp. (23S rRNA) were present in all water samples during both seasons. The majority (66%) of the exposure sites (bathroom taps) were positive for at least one target Legionellaspecies (listed above). Results showed that pathogenic Legionellaspecies were most often detected during the winter/spring sampling event – the percent positives for any one of the pathogenic Legionellaspecies at the hot-water taps was 80% in building F and 40% in BPS, M, FH, and ERC. Legionella pneumophilaand L. longbeachaewere found in the highest concentrations (2.0 log10gene copies (GC)/100 mL) at the hot-water taps in buildings F and ERC, respectively. No strong relationships were found with the physical–chemical parameters. Overall, general Legionellaspp. concentrations increased in the winter/spring samples due possibly to lower water usage (lower occupancy and no use of cooling towers, which led to more water stagnation or time in the system).