Key Genetic Analysis of Legionella Bacteria

Recent research has suggested that routine sampling of water supplies and genomic sequencing to determine the entire genetic makeup of Legionella bacteria could play a key role in identifying the source of Legionnaires' disease outbreaks. (Source here) 

 

Legionnaires' disease is a severe form of pneumonia — lung inflammation usually caused by infection. It's caused by a bacterium known as legionella. Most people catch Legionnaires' disease by inhaling the bacteria from water droplets. Older adults, smokers and people with weakened immune systems are particularly susceptible to Legionnaires' disease. 

 

A comparison of the entire genome or genetic code of more than 3,000 Legionella bacteria samples found in patients and water sources from Scotland and around the world was conducted by a team from the Universities of Edinburgh and Glasgow, Public Health Scotland, and the Scottish Legionella Reference Laboratory revealing a brand-new level of detail into the characteristics of Legionella bacteria and its transmission in Scotland. 

 

The analysis of the genetic code has shown that infections following travel were often closely related to other variants from the same U.K. or international travel destination. It also found that nearly one-third of infections in Scotland were acquired in the community—not hospital or travel associated—were caused by a single variant. The team say this variant should be closely monitored. 

 

The article goes on to say that distinct variants of the bacteria were found in some hospitals over a long period—up to 17 years in some instances—which suggests that the bacteria persisted or were repeatedly introduced into hospital water systems. 

 

The team also found that there had been no reported cases of Legionnaires' disease in any Scottish hospital in the past 10 years. This is likely due to the effectiveness of new control measures introduced during this time, experts say. 

 

Professor Andrew Smith, a co-author on the study from the University of Glasgow said, "As head of the Scottish Legionella Reference Laboratory it has been a privilege to be part of this study which is a fantastic exemplar of team-working involving National and Internationally recognised experts. 

 

"We have been able to have a more detailed understanding of the population biology of Legionella pneumophila informing future sampling strategies and also a framework for investigating sources of future outbreaks as part of public health control measures in Scotland." 

 

Professor Ross Fitzgerald, the lead researcher from the University of Edinburgh's Roslin Institute, said, "Our study indicates that regular sampling of water systems and genome sequencing of Legionella could be used to identify the source of new pathogenic variants before they become a clinical problem."