Testing the waters: Legionnaires’ disease and the Olympics

Over the next few weeks, we’ll be exploring the molecular methods that enable scientists to investigate disease outbreaks, often in real time. This week, research from the Journal of Medical Microbiology on dealing with outbreaks of Legionnaires’ disease.

Water was a big topic of conversation at the Olympics in Rio this year. Guanabara Bay,
where the sailing took place, was reported to be full of untreated sewage, as well as high levels of harmful bacteria and viruses. And over the course of the swimming events, first the diving pool and then water polo pool turned bright green due to unchecked growth of algae.


Now that the Paralympic swimming events are in full swing (well done Team GB!), we can only hope that the officials in Rio can keep the water blue and avoid another incident. But if we turn the clocks back to just before the 2012 Olympics in London, a group of scientists here in the UK were also thinking about water ­– and how to keep people safe from the pathogens lurking within it.

Legionnaires’ disease, a potentially life-threatening lung infection caused by Legionella bacteria, is caught by inhaling contaminated droplets of water. The bacteria are naturally present at low levels in ponds and rivers, but if they make their way into man-made water systems – like cooling towers, hot tubs and fountains – they can multiply and spread. They grow most rapidly at temperatures between 20–45°C, and impurities like rust and limescale (often found in the above systems) can fuel them with nutrients to do so.

Legionnaires’ disease can’t usually be spread from person to person, but a single contaminated water source could infect many people if it’s found in somewhere like a hospital, a hotel or a gym. So keeping tabs on incidents of Legionnaires’ disease when they do crop up is important to prevent outbreaks.

“An outbreak of Legionnaires’ disease in the Olympic Village, for example, would have been on every headline all over the world,” says Massimo Mentasti, an Advanced Healthcare Scientist at Public Health England (PHE). “So in preparation, we were trying to develop a rapid testing and typing protocol.”

Analysing DNA of the infecting strains (known as ‘typing’) can tell you a lot. If the strains from cases of Legionnaires’ disease are all the same type, they probably all originated from the same place, which implies a common contaminated water source. But if they are different, that tells you that the increase in cases isn’t linked to an outbreak – for example, hot dry weather after heavy rain makes people slightly more likely to contract Legionnaires’ disease from any source.

“You have to get a typing result as soon as possible,” says Massimo. “That would quickly trigger an environmental response to find the source of the outbreak. If you shorten this process, you can potentially save lives because fewer people will contract the disease.”

The trouble is, normally this typing process takes around eight to ten days. This is because Legionella bacteria take a long time to grow in the lab, at least a few days, before you can harvest enough DNA for the analysis. They are also very fussy, and can easily be outgrown by other bacteria.

To get round this, the team used a modification of the standard typing technique that quickly amplifies Legionella DNA in their samples to high levels, prior to analysis. “The new method is quicker because you don’t need to wait for the Legionella to grow and then do the typing procedure,” explains Massimo. “In this case, we use this method directly on the clinical sample, as soon as we know that it contains Legionella DNA.”

This meant that PHE scientists were able to characterise the infecting strains from suspected outbreaks much quicker – in just one and a half days compared to over nine days with the usual method.

“The results were brilliant,” says Massimo. “So we decided to adopt this approach for urgent cases and clusters when we have reason to suspect something is going on.”

For other pathogens, this kind of technique may not be appropriate, for example if the strains are easier to grow in the lab. But the long time it takes to culture and then type Legionella bacteria in the lab, and the high potential impact of outbreaks, mean that the rapid protocol they have developed can be a very valuable tool. The technique also allows them to type infecting strains in situations when they can’t be grown – like if they have been killed by antibiotics given to the patient.

In the end, the method was used during the Olympics at an outbreak in the Midlands. Since then, it’s also been used to confirm or exclude outbreaks of Legionnaires’ disease and provide crucial results in at least six other incidents. The authors have reported their findings in the Microbiology Society’s Journal of Medical Microbiology.

“We don’t use this method on a routine basis,” explains Massimo. “But when we need a quick response, it’s another powerful weapon that we have to tackle Legionella outbreaks.”

Anand Jagatia

Image credit: Shizhao on Wikimedia Commons under CC BY 2.5 CN; CDC in the Public Domain
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New to science: August 2016

Each month, the Microbiology Society publishes the International Journal of Systematic and Evolutionary Microbiology (IJSEM), which details newly discovered species of bacteria, fungi and protists. Here are a few of the new species that have been discovered and the places they’ve been found. The full papers are available to journal subscribers, but the abstracts are free to read.

Goodbye summer. Well, goodbye meteorological summer, which is based on the calendar. Astronomical summer, which is based on the movements of the Earth, doesn’t end until 22 September – so make the most of it.

The August issue of IJSEM is chock-full of microbes from interesting organisms and places –including the human body. Researchers from Germany have isolated the bacterium Prevotella colorans from a wound in a 77-year-old patient. And a team from the USA have discovered a new species from human abscesses, which they name Lawsonella clevelandensis.

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Microbe Talk: August 2016

I Contain Multitudes: An interview with Ed Yong


“Every one of us is a zoo in our own right – a colony enclosed within a single body. A multi-species collective. An entire world.”

Yong, Ed 2016 (1) - c Urszula Soltys

In this episode, we chat to science writer Ed Yong about his upcoming book and The New York Times Bestseller, I Contain Multitudes: The Microbes Within Us and a Grander View of Life.

It’s a book about the trillions of microbes that live on us and within us; microbes that build our bodies and organs, protect us from disease, shape our behaviour and drive the processes for life on earth.

Anand Jagatia

Don’t forget, you can subscribe to Microbe Talk on iTunes. You can also find us on Soundcloud and Stitcher.

Image credit: Urszula Soltys
Music: NeVe by Manuele Atzeni
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On the Horizon: Nipah Virus

FruitbatOur past two articles in the On the Horizon series have focused on diseases that were first identified decades ago. In this edition of the series, we’ll be looking at a virus that was only discovered at the very end of the 20th century, and the efforts being made to control it.

In late 1998, an outbreak of an unknown disease occurred in pigs and pig farmers in Kampung Sungai Nipah, a village in Malaysia. The transporting of infected pigs also led to cases of the disease being identified 200 miles away in Singapore. The outbreak caused almost 300 human cases and over 100 deaths were reported. Over a million pigs had to be destroyed at large economic cost to the region.

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From space to stomach ulcers

Could a machine for detecting molecules in space be used to identify bacteria that cause stomach ulcers? This is the question that Dr Geraint ‘Taff’ Morgan and his colleagues, Professors Ejaz Huq and Phil Prewett, from Oxford MicroMedical Ltd are trying to solve.

Their work centres on the study of stable isotopes, which are different forms of an atom that have varying amount of neutrons and protons in their nuclei. The majority of elements exist in multiple forms – for example, an oxygen atom can naturally occur with 16, 17 or 18 protons and neutrons within its nucleus and is denoted as 16O, 17O and 18O respectively. The isotopes of higher numbers are heavier and behave in a slightly different manner to their lighter counterparts. Continue reading

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Could we use bacteria to power tiny wind farms?

Sunset_at_Royd_Moor_Wind_FarmA single drop of fluid can contain billions of bacteria swimming around inside it. For the most part, the movements of these bacteria are random and chaotic. But if you look at them under the microscope, you begin to see patterns emerging – swirls and vortices that come in and out of existence as groups of bacteria briefly swim in the same direction.

Scientists refer to these kinds of systems as ‘active matter’. They are made up of large numbers of active individuals that take energy from their surroundings to move around. which means the system is out of thermal equilibrium.

Because of this, interesting collective behaviour can spontaneously arise as the individuals interact with each other in complex ways, like in flocks of birds or shoals of fish.

Under the right conditions, organised collective behaviour can also be seen in bacterial suspensions. For example, if you let bacteria swim round an array of small wells, they begin to move in a synchronised way, and a regular pattern arises. Continue reading

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Microbe Talk Extra: Handwashing and Healthcare-associated Infections

Nurse using hand sanitiserEvery year, hundreds of millions of patients across the world are affected by Healthcare-associated Infections, according to estimates from the World Health Organization (WHO). These infections can result from a surgery, or from the use of a medical device like a catheter, for example, and cause significant mortality and economic losses.

One of the things that hospital staff can do to prevent these infections is effective handwashing. In this podcast we spoke to Professor Didier Pittet, who has been leading a WHO campaign to promote the use of alcohol-based hand sanitiser in hospitals and clinics across the globe.

Benjamin Thompson

Don’t forget, you can subscribe to Microbe Talk on iTunes. You can also find us on Soundcloud and Stitcher.

Image credit: Bananastock/Thinkstock
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