LEGIONELLACEAE IN THE POTABLE WATER OF NOVA-SCOTIA HOSPITALS AND HALIFAX RESIDENCES

Water was cultured from 39 of 48 hospitals (7 Halifax hospitals and 32 non-Halifax hospitals) in the province of Nova Scotia and from 90 res idences (74 private dwellings, 16 apartments) in Halifax to determine the frequency of legionella contamination. Six of seven Halifax hospit als had Legionellaceae isolated from their potable water compared with 3 of 32 non-Halifax hospitals (P < 0.0001). Overall, 19 of 59 (32%) o f the water samples from Halifax hospitals were positive for legionell ae compared with 5 of 480 (1%) samples from non-Helifax hospitals (P < 0.0000). Five of the six positive Halifax hospitlals had Legionella p neumophila serogroup 1 and 1. had L. longbeachae serogroup 2 recovered from their potable water. Legionella contamination was associated wit h older, larger (equal to or greater than 50 beds) hospitals with tota l system recirculation. These hospitals also had water With a higher p H and calcium content but lower sodium, potassium, nitrate, iron and c opper content. Fourteen of the 225 (6.2%) water samples from Halifax r esidences were positive for legionellae - 8% (6/74) of the single fami ly dwellings were positive, compared with 25% (4/16) apartments. The p ositivity rate of 15.7% for the 19 electric hot-water heaters in Halif ax homes was not significantly different from the 32% positivity for H alifax hospitals. L. longbeachae accounted for 2 of the 14 isolates of legionellae from Halifax homes.