Typhoid Fever: A race against time

Salmonella-infected cells (macrophages in blue, monocytes in turquoise). Dead Salmonella (only yellow), surviving Salmonella (yellow and red). Credit: University of Basel

The life-threatening disease typhoid fever results from the ongoing battle between the bacterial pathogen Salmonella and the immune cells of the body. Prof. Dirk Bumann's research group at the Biozentrum of the University of Basel has now uncovered how the typhoid pathogen repeatedly manages to evade the host's immune system. Their findings are published in the scientific journal Cell Host & Microbe.

Typhoid fever is a bacterial infection caused by the pathogen Salmonella. The infected host's detects Salmonella and activates such as neutrophils and monocytes. These cells infiltrate the infected tissue and enclose the infection to form an abscess. Although most Salmonella bacteria are readily killed by this immune reaction, Dirk Bumann's group has demonstrated that some escape from the abscess and thus ensure their survival.

Salmonella uses immune cells

Once outside the abscess, the Salmonella bacteria are attacked by other immune cells, the so-called macrophages that produce a less effective immune response. "Salmonella have developed a range of defense strategies to resist macrophage attacks. Many Salmonella are thus able to survive and even to replicate in macrophages," explains Neil Burton, one of the two first authors. With time, abscesses form around the new infection foci but again some Salmonella bacteria can manage to escape. "This drives the whole infection process further and makes particularly insidious," says Nura Schürmann, also a first author of the publication.

A battle on many fronts

The whole disease process is a race between Salmonella and the immune system of the infected organism, in which the battle is fought on many fronts. In this process many Salmonella bacteria are killed and others survive to spread the infection. It is the net balance of the outcomes of these individual Salmonella and immune cell encounters which in the end determines the course of the illness.

Typhoid fever is a life-threatening infection in countries with poor hygiene. Each year, more than 20 million people are infected with this disease. The illness is transmitted by ingesting food or water contaminated with this bacterium. Once inside the intestine, Salmonella crosses the gut mucosa and spreads to other organs such as the spleen and liver. Growing antibiotic resistance makes this illness increasingly difficult to cure.

Understanding what factors enable Salmonella to win many encounters with host cells might provide new strategies in the treatment of typhoid fever. Similar heterogeneous encounters likely determine the fights between the and many other pathogens. Findings of this study may thus be relevant for a wide range of infectious diseases.

More information: Neil A. Burton, Nura Schürmann, Olivier Casse, Anne K. Steeb, Beatrice Claudi, Janine Zankl, Alexander Schmidt, Dirk Bumann." Disparate Impact of Oxidative Host Defenses Determines the Fate of Salmonella during Systemic Infection in Mice." Cell Host & Microbe, Volume 15, Issue 1, 72-83, 15 January 2014 | DOI: 10.1016/j.chom.2013.12.006

add to favorites email to friend print save as pdf

Related Stories

Salmonella jams signals from bacteria-fighting mast cells

Dec 12, 2013

A protein in Salmonella inactivates mast cells—critical players in the body's fight against bacteria and other pathogens—rendering them unable to protect against bacterial spread in the body, according to res ...

Recommended for you

3-D printing offers innovative method to deliver medication

3 hours ago

3-D printing could become a powerful tool in customizing interventional radiology treatments to individual patient needs, with clinicians having the ability to construct devices to a specific size and shape. That's according ...

Mystery of the reverse-wired eyeball solved

Feb 27, 2015

From a practical standpoint, the wiring of the human eye - a product of our evolutionary baggage - doesn't make a lot of sense. In vertebrates, photoreceptors are located behind the neurons in the back of the eye - resulting ...

Neurons controlling appetite made from skin cells

Feb 27, 2015

Researchers have for the first time successfully converted adult human skin cells into neurons of the type that regulate appetite, providing a patient-specific model for studying the neurophysiology of weight ...

Quality control for adult stem cell treatment

Feb 27, 2015

A team of European researchers has devised a strategy to ensure that adult epidermal stem cells are safe before they are used as treatments for patients. The approach involves a clonal strategy where stem cells are collected ...

User comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.