A note on the temperature tolerance of Legionella

A strain of Legionella pneumophila serogroup 1 isolated from the environment had a decimal reduction time in water at 50 degrees C (D50) of 111 min, a D54 of 27 min and a D58 of 6 min. There was little loss of viability at 46 degrees C. Other environmental organisms, a Pseudomonas sp., a Micrococcus sp. and a coliform survived less well at these temperatures. A species of Sarcina had a survival time greater than the L. pneumophila at all the temperatures tested. Other strains of legionellas were tested at 50 degrees C and decimal reduction times calculated. These ranged from 80 min for another strain of L. pneumophia serogroup 1 to 216 min for L. bozemannii . Legionella micdadei did not survive well at 50 degrees C.