Legionnaires' Disease in Pediatric Patients, Control Measures and 5-Year Follow-up

Background: Legionnaires' disease (LD) occurs predominantly in adults and elderly people. Its incidence in Europe has been increasing in recent years. It is rare in younger age groups and prone to be reported as healthcare-associated infection with a higher risk of fatal outcome. Hospital-acquired LD is mostly associated with a colonized hospital water system. We describe 5 LD cases in a children's hospital in Slovakia, subsequent environmental investigation, control measures, and 5-year monitoring ofLegionellacolonization in hospital's water system. Methods: In 2014-2019, we tested clinical specimens from 75 hospitalized patients. Respiratory samples were cultured forLegionella, patient's urine was tested forLegionellaurinary antigens, and the microagglutination test was used for serologic testing. Samples of water were collected in 2015-2019 and processed according ISO11731. Results: We identified 5Legionellainfections in 2014-2015. Median age of patients was 15 years. All were high-risk patients hospitalized for their underlying diseases. All patients required admission to intensive care unit, and artificial ventilation due to general deterioration and respiratory failure.Legionella pneumophilawas isolated from 72% of water samples. Chlorine dioxide dosing into water system above 0.3 ppm caused significant decrease ofLegionellaconcentration in water samples. Samples taken from outlets with antimicrobial filter installed were legionellae-negative. Conclusions: Control measures led to decreased risk of infection, but not to eradication ofLegionellae. It is necessary to extend the diagnostics forLegionellainfection in hospitalized children with pneumonia, especially in hospitals with colonized water system.