Effect of rubbers and their constituents on proliferation of Legionella pneumophila in naturally contaminated hot water.

The proliferation of Legionella pneumophila serogroups 1, 9, and 10 in naturally contaminated hot potable water was measured after the addition of various rubbers and their constituents. When compared with controls 9/14 rubbers and 15/30 constituents shortened lag time for growth of L pneumophila at 37 degrees C and, produced a 10-100 000 fold increase in the number of L pneumophila organisms. In most experiments this increase was due mainly to the growth of L pneumophila serogroup 10, which predominated in all fresh water samples (47-53 degrees C); in others a shift in predominance from serogroup 10 to serogroup 1 occurred. Rubbers containing thiuram did not enhance the growth of L pneumophila, while the addition of thiuram alone inhibited growth. Therefore thiuram-containing rubbers should be used in water systems.