Snapshots of Life: Fighting Urinary Tract Infections

Urinary tract infection in a mouse

Source: Valerie O’Brien, Matthew Joens, Scott J. Hultgren, James A.J. Fitzpatrick, Washington University, St. Louis

For patients who’ve succeeded in knocking out a bad urinary tract infection (UTI) with antibiotic treatment, it’s frustrating to have that uncomfortable burning sensation flare back up. Researchers are hopeful that this striking work of science and art can help them better understand why severe UTIs leave people at greater risk of subsequent infection, as well as find ways to stop the vicious cycle.

Here you see the bladder (blue) of a laboratory mouse that was re-infected 24 hours earlier with the bacterium Escherichia coli (pink), a common cause of UTIs. White blood cells (yellow) reach out with what appear to be stringy extracellular traps to immobilize and kill the bacteria.

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Snapshots of Life: Portrait of a Bacterial Biofilm

Colony of Pseudomonas aeruginosa

Credit: Scott Chimileski and Roberto Kolter, Harvard Medical School, Boston

In nature, there is strength in numbers. Sometimes, those numbers also have their own unique beauty. That’s the story behind this image showing an intricate colony of millions of the single-celled bacterium Pseudomonas aeruginosa, a common culprit in the more than 700,000 hospital-acquired infections estimated to occur annually in the United States. [1]. The bacteria have self-organized into a sticky, mat-like colony called a biofilm, which allows them to cooperate with each other, adapt to changes in their environment, and ensure their survival.

In this image, the Pseudomonas biofilm has grown in a laboratory dish to about the size of a dime. Together, the millions of independent bacterial cells have created a tough extracellular matrix of secreted proteins, polysaccharide sugars, and even DNA that holds the biofilm together, stained in red. The darkened areas at the center come from the bacteria’s natural pigments.

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Mouse Study Finds Microbe Might Protect against Food Poisoning

T mu in a mouse colon

Caption: Scanning electron microscopy image of T. mu in the mouse colon.
Credit: Aleksey Chudnovskiy and Miriam Merad, Icahn School of Medicine at Mount Sinai

Recently, we humans have started to pay a lot more attention to the legions of bacteria that live on and in our bodies because of research that’s shown us the many important roles they play in everything from how we efficiently metabolize food to how well we fend off disease. And, as it turns out, bacteria may not be the only interior bugs with the power to influence our biology positively—a new study suggests that an entirely different kingdom of primarily single-celled microbes, called protists, may be in on the act.

In a study published in the journal Cell, an NIH-funded research team reports that it has identified a new protozoan, called Tritrichomonas musculis (T. mu), living inside the gut of laboratory mice. That sounds bad—but actually this little wriggler was potentially providing a positive benefit to the mice. Not only did T. mu appear to boost the animals’ immune systems, it spared them from the severe intestinal infection that typically occurs after eating food contaminated with toxic Salmonella bacteria. While it’s not yet clear if protists exist that can produce similar beneficial effects in humans, there is evidence that a close relative of T. mu frequently resides in the intestines of people around the world.

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LabTV: Curious About Bacteria

Robert Morton IIIOther than wondering what might be lurking in those leftovers stashed in the back of the fridge, you probably don’t think much about bacteria. But Robert Morton III—a Ph.D. candidate at Indiana University, Bloomington, and the focus of our latest LabTV profile—sure does. He’s fascinated by the complicated and even beautiful ways in which bacteria interact with their environments. In fact, scientists can learn a whole lot about biology by studying bacteria and other single-celled organisms.

Working in the NIH-funded lab of Yves Brun, Morton has spent many of his days peering through microscopes into the otherwise invisible world of bacteria. His sights are set on the relatively simple, two-component interactions that enable bacteria to sense and respond to various external factors. Each of these interactions features a histidine kinase sensor partnered with a response regulator. Specifically, Morton has focused much of his research on one particular protein thought to play a role in these interactions—a protein that he calls an “orphan” because no scientist has yet identified its partner or determined quite what it does.

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LabTV: Curious About Tuberculosis

LabTV-Bree AldridgeOne reason that I decided to share these LabTV profiles is that they put a human face on the amazingly wide range of NIH-supported research being undertaken every day in labs across the country. So far, we’ve met young scientists pursuing basic, translational, and clinical research related to the immune system, cancer, Alzheimer’s disease, and the brain’s natural aging process. Today, we head to Boston to visit a researcher who has set her sights on a major infectious disease challenge: tuberculosis, or TB.

Bree Aldridge, PhD, an assistant professor at Tufts University School of Medicine in Boston, runs a lab that’s combining microbiology and bioengineering in an effort to streamline treatment for TB, which leads to more than 2 million deaths worldwide every year [1]. Right now, people infected with Mycobacterium tuberculosis—the microbe that causes TB—must take a combination of drugs for anywhere from six to nine months. When I was exposed to TB as a medical resident, I had to take a drug for a whole year. These lengthy regimens raise the risk that people will stop taking the drugs prematurely or that an opportunistic strain of M. tuberculosis will grow resistant to the therapy. By gaining a better basic understanding of both M. tuberculosis and the cells it infects, Aldridge and her colleagues hope to design therapies that will fight TB with greater speed and efficiency.

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