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Bacterial Pathogenesis

Members of the Faucher lab have a focused interest on the behavior of bacterial pathogens in non-clinical environments, such as in water. Survival and perhaps growth of water-borne pathogen in this environment is crucial for its transmission to its host. What are the genetic factors and environmental factors that influence its behavior in the non-clinical environment and its further transmission to the host are among the top questions that are shaping our research.

We use deep sequencing tools extensively to answer these questions, and the data generated from these studies are used to identify new systems and microbial interactions that promotes the survival, growth and spread of pathogens in the environment.

Our primary model organism is Legionella pneumophila, a Gram-negative pathogen that can be found in almost any natural or human-made water system. L. pneumophila is able to replicate inside a wide diversity of phagocytic protozoans found in water. It is the causative agent of Legionnaires' disease, an acute form of pneumonia. After inhalation of contaminated water droplets, Legionella infect and replicate inside alveolar macrophages. This phenotype is completely dependent on a Type IVb secretion system that translocates ~200 effectors into the host cells. These effectors modify the normal phagocytic pathway to the benefit of Legionella. Many regulators are known to play a role in the expression of virulence factors, such as two-component systems and small regulatory RNAs (sRNA). 

Human macrophages (grey circles) infected with green-fluorescent L. pneumophila. The green circles are macrophages infected and completely filled with L. pneumophila. The infected macrophage will soon explode, releasing hundreds of L. pneumophila that will then infect fresh macrophage. Source: Thangadurai Mani.

Model cooling tower build by Adriana Torres to study the interaction of Legionella pneumophila with the biofilm. Source: Adriana Torres.


There is no sin in being ignorant; the sin is to remain ignorant.

Roy Curtiss III

In the fields of observation, chance favors only the prepared mind.

Louis Pasteur

I believe in evidence. I believe in observation, measurement, and reasoning, confirmed by independent observers. I'll believe anything, no matter how wild and ridiculous, if there is evidence for it. The wilder and more ridiculous something is, however, the firmer and more solid the evidence will have to be.

Isaac Asimov


Sebastien P. Faucher

Associate Professor

Department of Natural Resource Sciences

McGill University

21,111 Lakeshore Rd.

Ste. Anne de Bellevue, QC

H9X 3V9

Tel: 514-398-7886




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