Prevalence study of Legionella spp. contamination in Greek hospitals

Area of Science:

• Environmental microbiology
• Hospital-acquired infections

Background:

• Legionella is a bacterium that can cause Legionnaires' disease, a severe form of pneumonia.
• Hospitals are environments where Legionella can proliferate in water systems, posing a risk to patients.

Purpose of the Study:

• To investigate the prevalence and characteristics of Legionella in hospital water systems.
• To identify potential sources and environmental factors favoring Legionella growth.
• To assess the association between staff immune response and environmental Legionella levels.

Main Methods:

• Water and swab samples were collected from 13 hospitals.
• Samples were analyzed for Legionella counts and serotypes.
• AFLP typing was used for L. pneumophila ser. 1 strains.
• Serum samples from staff were tested for IgG titres.

Main Results:

• Legionella was detected in 8 out of 13 hospitals and 22 out of 130 samples.
• L. pneumophila ser. 1 was the predominant serotype (72.7%).
• Cooling towers were more likely to harbor Legionella than other water systems.
• Water temperatures between 30-40°C favored Legionella growth.
• No significant correlation was found between sample type and Legionella recovery.
• AFLP typing identified two main types of L. pneumophila ser. 1.
• 89.4% of staff serum samples were negative for IgG antibodies, with 7.2% positive and 3.4% doubtful.
• No association was detected between staff IgG titres and environmental Legionella levels.

Conclusions:

• Legionella is prevalent in hospital water systems, with cooling towers being a significant reservoir.
• Environmental factors like temperature play a role in Legionella proliferation.
• Current staff IgG titres do not appear to be directly associated with the observed levels of Legionella in the hospital environment.