Control measures needed in water systems to reduce Legionellae infection

A recent study has shown the effectiveness of control measures in reducing, but not eradicating, the risk of infection with Legionellae, the bacteria that causes the legionnaires disease (LD).

“It is necessary to extend the diagnostics for Legionella infection in hospitalized children with pneumonia, especially in hospitals with colonized water system,” the authors said.

Clinical specimens from 75 hospitalized patients were tested in 2014–2019. Respiratory samples were cultured for Legionella, while urine samples were tested for Legionella urinary antigens. In addition, the microagglutination test was used for serologic testing. Finally, the authors collected water samples in 2015–2019 and processed these according to ISO11731.

In 2014–2015, five Legionella infections were identified in a children’s hospital in Slovakia. Patients had a median age of 15 years, and all were at high risk and hospitalized due to underlying diseases. Moreover, all patients required intensive care and artificial ventilation due to general deterioration and respiratory failure.

The authors isolated Legionella pneumophila from 72 percent of water samples. Administration of chlorine dioxide above 0.3 ppm into the water system significantly reduced Legionella concentration in water samples. Samples taken from outlets with antimicrobial filter installed tested negative for Legionellae.

“LD occurs predominantly in adults and elderly people… It is rare in younger age groups and prone to be reported as healthcare-associated infection with a higher risk of fatal outcome,” the authors said.

“Hospital-acquired LD is mostly associated with a colonized hospital water system,” they added.