Thursday, 01 December 2011 11:16

mBio Study: New compound to control Listeria

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Cantaloupe contaminated with the bacterium Listeria monocytogenes killed 29 people in the U.S. this year in the deadliest foodborne outbreak since 1924, but the pathogen usually strikes in less public ways, quietly sickening an average of 1,600 people per year, according to the CDC. The authors of a study in mBio this week screened 57,000 small molecules to find one compound that can stop Listeria in its tracks. This needle-in-the-haystack approach has turned up a compound that could lead to novel therapeutics for listeriosis and other infections.
Antibiotics: they’re not just for curing the sick. Livestock farms in the U.S. regularly use antibiotic drugs as feed additives to boost animal growth, but a study in mBio this week reveals new evidence that adding antibiotics to pig feed stimulates gene exchange in the guts of these animals, a development that could move antibiotic resistance genes where they’re not wanted.
A parasite of animals (most notably cats) and humans alike, Toxoplasma gondii can boast a global distribution. But it’s not exactly the same organism the world over: one clonal type predominates in Europe and North America and another leads the pack in South America. One thing they do have in common is a chromosome called Chrla, which appears to interact with a major T. gondii virulence factor. Chrla is present in T. gondii isolates from all these regions. So, even though T. gondii from North America and Europe has many marked differences from South American isolates, you can still find…
Antibiotic-resistant enterococci are a serious problem for patients in the hospital, but little is known about how these bacteria are able to escape antibiotics. In mBio this week, Kristich et al. lay out some new discoveries about the ways in which enterococci turn their resistance to cephalosporin antibiotics on and off. The new details could lead to new therapies for preventing and treating enterococcal infections.
Antivirulence drugs disarm pathogens rather than kill them, and although they could be effective in theory, antivirulence drugs have never been tested in humans. A new study to in mBio this week reveals these drugs have the potential to fight infection while avoiding the pitfalls of drug resistance.
It may hardly seem like news, but here’s the latest: raw sewage is loaded with viruses. That’s the part you may have already guessed. The more astounding aspect of a study published in mBio this week is the diversity those viruses represent. Biologists have described only a few thousand different viruses so far, but this latest study reveals that raw sewage is home to the most diverse array of viruses ever found. Apparently, a vast world of unseen viral diversity exists right under our noses.
Neisseria gonorrhoeae, the bacterium behind “the clap”, has several tools in its shed to help it evade antibiotics. One such tool is the multidrug efflux pump MtrC-MtrD-MtrE, which shuttles low concentrations of antimicrobials out of the cell before they can take their toxic toll. In mBio this week, researchers describe a single point mutation that enables N. gonorrhoeae to dramatically increase production of this efflux pump without touching the promoters or repressors that normally control its manufacture.
Why did so many of the people who died from the new strain of H1N1 influenza that broke out in 2009 also have pneumonia? The authors of a study in mBio this week found out how the two infections, pandemic flu and pneumonia, interact to make to make a lethal combination: infection with the pandemic strain of flu caused more extensive damage to the lung epithelium than seasonal flu. The damage requires more extensive tissue repair and opens the body up to attack from bacterial invaders like Streptococcus pneumoniae.
The current vaccines for pneumococcal disease have succeeded in some ways and failed in others, and we still have a lot to learn about vaccine-mediated protection. A study out in mBio this week reveals that some antibodies instigate a Greek tragedy among pneumococci: they get the bacteria to kill their own “brother” cells.
Thursday, 08 September 2011 10:18

Sorry lab rats: E. coli is still cooler than you

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E. coli K-12 is a lot like your average lab rat: predictable, well-understood, and tame. However, there’s at least one important difference between a white rat and K-12: the rat can’t mutate and become a voracious, man-eating scourge.
Despite the great strides medicine has made in the past century, diagnosing infectious disease remains a difficult – and often impossible – task. One major barrier in diagnosis is the simple problem of knowing what to look for. Which of the millions of potentially antigenic products that a pathogen makes can actually be found in bodily fluids and used as indicators of infection? After all, not every protein or polysaccharide belonging to a pathogen can make it into a handy sample of urine or blood, so which CAN we use?
Wednesday, 07 September 2016 13:22

Fighting Zika with Functional Fashion

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Function is often thought of as the tradeoff for high fashion, but who says you can’t have both? Fawn Jordan, 2016-2017 DC Fashion Incubator Designer in Residence, is seeking to unite the two to help protect women against potentially Zika-transmitting mosquitoes. Her recent collection combines two major mosquito avoidance methods: skin-covering clothing and mosquito netting.
Gruesome, ghastly, grisly. These are the words that popped into my head when I googled images of diabetic foot ulcers—one of the most common chronic wounds creating a silent and costly epidemic in healthcare.
When Candida albicans encounters stressful conditions, does it curl up and die? No! According to a paper just published in mBio, this crafty pathogen gets to work on its inventory of genes, slashing away until it finds a winning combination that can get it through the tough times. (I’ve written up other mBio papers about Candida here and here. I think I am gaining a grudging respect for this feisty fungus.)
Tuberculosis is no picnic, but taking the required medicines to treat the disease is a long slog: it takes six months, at least, to treat TB. To prevent patients from quitting treatment too soon, many doctors insist on “directly observed therapy”, where patients take their antibiotics under the watchful eye of a medical professional. However, they may also give their patients a weekly 2-day vacation from treatment. Taking a “drug holiday” from TB antibiotics not only offers patients a break from seeing their doctor every day, it can also boost the effectiveness of the drugs and increase patient adherence to…
A search goes faster with a tool to separate the wheat from the chaff. A pan can help you find gold flakes, and a metal detector can help you find a coin at the beach, but what tools can you use when you’re searching for a bacterium that can manufacture biofuels? In a study in mBio this week, researchers applied an old familiar microscopy tool in a new high-throughput method to help identify new strains of hydrocarbon-making microbes.
In the hunt for new organisms, sometimes you just get lucky. The authors of a paper in mBio this week found a virus that offered two discoveries for the price of one: it’s a novel organism that also reveals lessons in evolutionary ecology.
To get around host defenses, Salmonella enterica serovars that specialize in a single type of host are known to shuffle their genomic decks by recombining their chromosomes, rearrangements that result in inversions, translocations, duplications, or deletions of various sizes.
When a successful bacterium begins to outgrow its physical niche, things can get ugly. Colonies Paenibacillus dendritiformis, for instance, turns on its brothers and produces a toxic protein called Slf, which kills cells of encroaching sibling colonies. The bacterium senses when space gets tight, then deploys its toxic protein on nearby colonies so it won’t lose out in the struggle for space and nutrients.
I attended the ASM General Meeting in New Orleans this week and soaked up some science and some amazing New Orleans cuisine. I also loaded up on vendor tchotchkes. While browsing around the vendor booths I managed to acquire no fewer than FOUR bottles of hand sanitizer. After reading the latest in mBio, I'm glad I did.