Peracetic acid in the disinfection of a hospital water system contaminated with Legionella species.
OBJECTIVE
To assess the efficacy of an alternative disinfection method for hospital water distribution systems contaminated with Legionella.


METHODS
Disinfection with peracetic acid was performed in a small hospital contaminated with L. pneumophila serotype 1. The disinfectant was used at concentrations of 50 ppm (first three surveillance phases) and 1,000 ppm (fourth surveillance phase) for 30 minutes.


RESULTS
Environmental monitoring revealed that disinfection was maintained 1 week after treatment; however, levels of recontamination surpassing baseline values were detected after approximately 1 month. Comparison of water temperatures measured at the distal outlets showed a statistically significant association between temperature and bacterial load. The circulating water temperature was found to be lower in the two wards farthest away from the hot water production plant than in other wards. It was thought that the lower water temperature in the two wards promoted the bacterial growth even after disinfection.


CONCLUSIONS
Peracetic acid may be useful in emergency situations, but does not provide definitive protection even if used monthly.
Ditommaso
Savina
S
Dipartimento di Sanittà Pubblica e di Microbiologia, Università degli Studi di Torino, Torino, Italy. savina.ditommaso@unito.it
Biasin
Cinzia
C
Giacomuzzi
Monica
M
Zotti
Carla Maria
CM
Cavanna
Alberto
A
Ruggenini Moiraghi
Angela
A
D015169:Colony Count, Microbial; D004202:Disinfectants / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D007875:Legionella / Q000187:drug effects* / Q000302:isolation & purification; D008284:Maintenance and Engineering, Hospital; D010463:Peracetic Acid / Q000494:pharmacology*; D013696:Temperature; D014871:Water Microbiology
D004202:Disinfectants; D010463:Peracetic Acid