Year of selection 2015
Institution Institut Pasteur in New Caledonia
Some bacteria can build their own suit of armor. Recently, researchers discovered the use of this protective structure in a new type of bacteria, Leptospira, that causes disease in humans and whose impact is likely to grow. This is important, because it could explain how the bacteria are able to survive for months in the environment and inside animal hosts. Leptospira is transmitted to humans mainly through water contaminated by the urine of other infected mammals. This environmental exposure is expected to grow as climate change brings heavier rainfall and increased flooding to the tropical zones where the disease is most prevalent, making it essential to understand how Leptospira circulate and what allows them to survive and multiply. Dr. Roman Thibeaux believes the previously unknown defensive structure used by the bacteria, called a biofilm, may be providing them with a safe haven that urgently requires further investigation. If he can understand its composition, formation and function, he may also find ways to create a chink in this bacterial armor, providing new ways to fight transmission.
Bacterial biofilms are multicellular communities of bacteria that are stuck together, and often to a surface, via a matrix they produce collectively themselves. This protective covering surrounds and defends them against both the immune system of their host and harsh environmental conditions, like UV exposure, dehydration, salinity and lack of nutrients. To begin his investigation, Dr. Thibeaux will search for Leptospira biofilms in natural habitats in New Caledonia, in the South Pacific. Leptospirosis is especially common to humid tropical zones and he will focus on “hot spots”, where infection rates are as much as ten times higher than other areas in the region. Water and soil samples will allow him to explore the environmental conditions that favor biofilm development, like temperature, pH, oxygen levels and more.
Back in the lab, Dr. Thibeaux will check for live Leptospira bacteria surviving inside the biofilms. This would mean that, contrary to current beliefs about the disease, Leptospira can reproduce in the environment, outside of a mammalian host. He’ll then investigate how, precisely, the biofilms work to protect the bacteria: What is their composition and how are they organized? Using advanced microscopy, he’ll even be able to observe their assembly over time.
These results will provide a thorough description of how Leptospira biofilms operate, offering new clues for evaluating the risk of leptospirosis outbreaks, as well as a much deeper understanding of the physical and chemical factors influencing the bacteria’s survival. Dr. Thibeaux’s work could indicate ways to impair their ability to generate biofilms, suggesting strategies for public health interventions that could make Leptospira vulnerable to the host’s immune system and to harsh conditions in the environment. Leptospirosis is already costly and can be life threatening; with the number of cases expected to increase to over a million per year worldwide, new approaches to treatment and prevention are badly needed.
Scientific title: Leptospires Bacterial Biofilm: An Unexplored Reservoir For Environmental Survival And Persistence Of Infectious Bacteria
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