Studying bacteria that cause human diseases as if they were ecological communities could help improve the way doctors treat diseases such as cystic fibrosis (CF), according to new research presented at the British Ecological Society's Annual Meeting at the University of Birmingham this week.Illustration of bacteria (Shutterstock)

While some ecologists study plants or animals, Dr Christopher van der Gast of the Centre for Ecology & Hydrology (CEH) is part of a team of ecologists and clinicians working on the bacterial communities that inhabit the lungs of people with CF.

CF is a genetic disorder affecting around 9,000 people in the UK alone. People with CF typically suffer from chronic airways disease caused by bacterial infection, and as 95% of CF sufferers die from respiratory infections, doctors need better ways of treating them.

The traditional medical approach has been to diagnose these lung infections by taking sputum samples from CF patients and looking for a select group of disease-causing bacteria, such as Pseudomonas aeruginosa and Staphylococcus aureus, by culturing them on agar plates.

While this approach pinpoints the harmful bacteria, it tells clinicians nothing about the dozens of other bacteria that make up the microbial community of the lung. Dr van der Gast explained, “The traditional approach is to focus on key known pathogens using diagnostic microbiology – what you can grow on an agar plate. But we cannot grow every bacteria from a given habitat on an agar plate because they all need different growth media.”

Instead, the research team is using ecological models and high-throughput sequencing to get a complete picture of the bacterial community in the lungs of patients with CF.

They are currently collecting sputum samples from 1,000 CF patients in the UK and US, which are being sequenced by the Wellcome Trust Sanger Institute in Cambridge. This large new study will build on earlier work that has already produced fascinating findings.

Microbial diversity

The team found for the first time that lung function in CF is linked to microbial diversity – that paradoxically as lung function worsens, microbial diversity crashes and particular bacteria become dominant – and that sputum samples from CF patients contain hundreds of species of bacteria in very variable communities.

"As well as the pathogens, we found a surprisingly diverse community of bacteria," Dr van der Gast said. "The pathogens don't just exist on their own, they are part of a complex ecosystem. By using ecological models to identify core species we can help improve treatments for CF patients."

"We are, for the first time, treating infectious diseases as ecological communities, not just infections, using ecological insights for clinical benefit." Dr Christopher van der Gast, CEH 

"In order to treat what's there, you have to know what's there and what it's doing. It seems obvious, but it's not been done in the past. We are for the first time treating infectious diseases as ecological communities, not just infections, using ecological insights for clinical benefit.”

These ecological insights could also benefit people suffering from other respiratory infections, which the World Health Organization has identified as one of the leading causes of human morbidity and mortality.

According to Dr van der Gast, “Getting a handle on these infections is important for CF patients, but it's also important for people with other lower respiratory tract infections and conditions such as Chronic obstructive pulmonary disease (COPD), which affects more than one million people in the UK. Applying ecological approaches may provide fresh insights into many other clinical scenarios.”

Dr van der Gast presents the findings today, Tuesday 18 December 2012, to the British Ecological Society’s Annual Meeting at the University of Birmingham.

Additional information

The British Ecological Society issued a press release for this story.

A full programme for the British Ecological Society Annual Meeting is available from the BES website.

CEH science at the 2012 BES Annual Meeting

Staff page and research interests of Dr Christopher van der Gast




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