Are pathogenic Legionella non-pneumophila a common bacteria in Water Distribution Networks?

Area of Science:

• Environmental microbiology
• Public health
• Bacteriology

Background:

• Artificial aquatic systems in facilities can harbor bacteria.
• Legionella species pose a significant public health risk through aerosol generation.
• Understanding Legionella prevalence in various water systems is crucial for risk assessment.

Purpose of the Study:

• To determine the national prevalence of Legionella in Spanish state-owned facility water systems.
• To analyze the geographical and annual distribution of Legionella isolates.
• To characterize Legionella non-pneumophila species using molecular techniques.

Main Methods:

• Collection and microbiological culture of 1754 water samples from diverse systems (cooling towers, water networks, fountains) over 12 months.
• Isolation and quantification of Legionella according to UNE-EN-ISO 11,731:2007 and UNE-EN ISO 8199:2008 standards.
• Molecular techniques for characterizing Legionella non-pneumophila isolates.

Main Results:

• Legionella was detected in 15.79% of analyzed water samples across 14 of 18 Spanish locations.
• High colonization rates were observed in cooling towers, domestic hot water, cold water, and decorative fountains.
• Legionella non-pneumophila (72%) was the most prevalent, with L. anisa and L. jordanis frequently isolated. L. donaldsonii was newly identified in Spanish water networks.

Conclusions:

• The presence of Legionella pneumophila and non-pneumophila species in artificial aquatic systems represents a potential public health threat.
• Routine diagnosis should incorporate molecular techniques for efficient screening.
• Continuous monitoring and risk management strategies are essential for preventing Legionnaires' disease.