CLINICAL APPLICATION Legionella pneumophila in hospital water distribution sult,
ID: 281906 • Letter: C
Question
CLINICAL APPLICATION Legionella pneumophila in hospital water distribution sult, hospitals are investigating eradicatin to determine the effects of heat (50°C), light area. D method? If the rates continue, which method(s) will kill all the bacteria in 320 minutes? systems has been linked to ne methods for eradicating Legionella in their water systems. Plate counts were used ata are shown ozone, and UV light area. Data are shown below. Which is the most effective L. pneumophila (CFU/ml) Time (min) Control 23 C 1 x 107 2×107 Ozone at 23°C UV light at 23°C 1 x 10 1 x 10 1 x 10 1 x 10* 1 x 10 0 1 × 107 1 x 10 1 x 10 1 x 10 1 x 10 1 x 10 20 1×107 5 × 107 6 x 10 9 x 107 1 x 10 5 x 10 1 x 10 40 160 320 1 x 10Explanation / Answer
The UV light method kill all the bacteria in 320 minutes.
The legionellae are highly susceptible to UV irradiation. In the dark, a 90% reduction has been achieved. On exposure to photoreactivating light, however, doses at least 3 times higher are needed because of the organism’s effective light-dependent DNA repair system.