Background and objective: Superheat-and-flush is one of the methods of disinfection used against Legionella in hospital water distribution systems. An outbreak of nosocomial legionellosis (NL) was detected in the hospital Germans Trias i Pujol in January 1996. The aim of this study was to evaluate the impact of this disinfection technique at an environmental and clinical level.
Material and method: Water samples were collected daily from central and tap water points 3 days prior to 15 days after superheating and flushing. Clinical surveillance of NL was performed 30 consecutive days following disinfection.
Results: After superheat-and-flush, the inoculum of Legionella pneumophila decreased in the central points but increased after day 11, achieving maximum values at 15 days. On the other hand, L. pneumophila was not detected in tap water points after 4 days but recolonization was observed after day 7, achieving 66% at day 9. No clinical cases of NL were detected during the study period.
Conclusions: Superheat-and-flush is an effective albeit transitory method of rapid disinfection in outbreaks of NL.