At what temperature range can Legionella pneumophilia bacteria survive?

Legionella pneumophila bacteria thrive in warm water environments typically found in man-made water systems such as cooling towers, hot tubs, and large plumbing systems. The optimal growth temperature for these bacteria ranges between 20 °C and 55 °C. Within this temperature range, they can proliferate significantly, leading to potential outbreaks of Legionnaires' disease, which can occur when aerosolized droplets containing the bacteria are inhaled.

Temperatures below 20 °C are usually too cool for Legionella to survive effectively, while temperatures over 60 °C are generally lethal to the bacteria, especially as water reaches sterilization temperature ranges. Although temperatures between 55 °C and 70 °C may allow them to survive temporarily, extended exposure to those higher ranges typically reduces their numbers significantly. Thus, the primary concern for managing Legionella is in the moderate temperature range from 20 °C to 55 °C, making this the correct answer.