Commensals
kbonham | March 1, 2013[This is my latest review for Download the Universe]
Honor Thy Symbionts, by Jeff Leach. Kindle
In 2003, the Human Genome Project--an effort to sequence every gene in a human being--was completed. The success, announced to great fanfare, was supposed to herald a new era in health care. Unfortunately, the promises of personalized medicine, in which treatments are tied to a person's genetic sequence, have not yet come to fruition. A few of the reasons for this are obvious (at least in hindsight). Knowing the location and sequence of a gene is one thing, knowing what it does is quite another.…
kbonham | January 21, 2013[This question was originally asked on www.reddit.com/r/askscience on Jan 17, 2013]
Why do microorganisms only begin breaking down our tissues after death? What stops them from doing so whilst we are still alive?
The main reason is that our body maintains a multitude of barriers that largely prevent bacteria and other microorganisms from gaining entry. The first and most obvious of these barriers is the skin, but there are also similar barriers along all of your mucosal surfaces (gut, ear, genital tract etc). These barriers consist of cells that are knit together incredibly tightly (google:…
kbonham | July 5, 2011There's a great post at the Sciam guest blog describing the science of antimicrobial cleaners, and it doesn't look promising:
perhaps the most comprehensive study of the effectiveness of antibiotic and non-antibiotic soaps in the U.S., led by Elaine Larson at Columbia University (with Aiello as a coauthor), found that while for healthy hand washers there was no difference between the effects of the two, for chronically sick patients (those with asthma and diabetes, for example) antibiotic soaps were actually associated with increases in the frequencies of fevers, runny noses and coughs. In…
kbonham | June 1, 2011You've all heard of Malaria. It's bad. It infects hundreds of millions of people, mostly in developing nations. It rarely leads directly to death*, but the resulting illness can lay people out for days or weeks, increasing an already heavy economic burden on many of the poorest countries in the world.
Folks from affluent regions can get medication to prevent or treat the illness, but treatments can be expensive and have nasty side effects, so it's not practical for most of the population. The good news is that Plasmodium, the parasite that causes the disease, can only be transmitted by…
kbonham | April 21, 2011When I first got into blogging, I thought I could carve out my niche talking about the microbiome - that enormous ecosystem of trillions living inside and on every one of us. However, it's become increasingly clear that writers far more skilled than I have also decided to tackle this weighty (2-5lbs on average) subject.
Take this new paper published yesterday in Nature, describing 3 different "enterotypes" - different ways of balancing that ecosystem. I saw it last night in my Nature RSS feed, and was hoping to tackle it today.
But Ed and Carl beat me to it with a couple of stereotypically…
kbonham | March 9, 2011I saw this link on a friend's facebook page, and left that tab open in my browser for a while, intending to write a post on it.
Professor Charles Gerba, the lead researcher, swabbed the handles of 85 carts in four states for bacterial contamination.
Gerba says 72% of the carts had a positive marker for fecal bacteria. When they examined some of the samples, they found Escherichia coli, also known as E. coli, on half of them.
I just couldn't muster the energy. Thankfully, Mike the Mad Biologist took care of this one.
both S. aureus and E. coli are commensal organisms: they live on and in us,…
kbonham | February 28, 2011I started writing a lengthy response to a reader comment on one of Heather's posts, but decided it could use a post of it's own.
The question:
As to being pathogenic, is it possible that many bacteria are pathogenic if given sufficient opportunity?
[snip]
It seems largely to me that the line between pathogenic and non-pathogenic is pretty blurry.
Totally.
Let's get some definitions out of the way first - a pathogen is an organism that causes disease. That seems simple enough, but when you examine the real world more carefully, things turn complicated pretty fast. What do I call the cold I was…
kbonham | February 23, 2011If you were going to design the perfect immune system, what would you do? This question is often posed to beginning immunology students, and the best answer may be so obvious that it doesn't occur to most. The best immune system is one that prevent pathogens from ever gaining access to your squishy bits in the first place.
And so we have barriers - lots of them. Unfortunately, the best barriers are not always practical. Plants have rigid cell walls that are almost impervious to pathogens, but plants don't need to walk around. We trade that in for skin and that does pretty well, but it has…
kbonham | February 1, 2011PalMD has a great post about vaginas. More specifically, about the wonderful commensal bacteria that help keep a vagina at the proper pH, and what happens when they get booted out:
From time to time, this normal balance of bacteria is disrupted. When this happens, the normally dominant Lactobacilli are outgrown by various anaerobic bacteria. These bacteria break down proteins in the vagina and create various malodorous compounds that are discharged in a thin, grey discharge. It is this symptom that normally drives a woman to the doctor where she is diagnosed with bacterial vaginosis (BV).…
kbonham | January 4, 2011The vermin only teaze and pinch
Their foes superior by an inch.
So, naturalists observe, a flea
Has smaller fleas that on him prey;
And these have smaller still to bite 'em,
And so proceed ad infinitum*:-Jonathan Swift
Even though I study the immune system, it always amazes me just how many creatures make their living by parasitizing other creatures. It's like the food chain turned on its head. The food chain you probably learned about in school says that many organisms feed on other organisms, which get fed on by others until you reach whatever ultimate predator sits at the top of the food…
kbonham | December 26, 2010As Boston gets buried under a layer of snow (wooo! blizzard!), the the Weekend Review makes a return with one of my favorite topics: gut microbes.
The fields of immunology, microbiology, nutrition and metabolism are rapidly converging. Here we expand on a diet-microbiota model as the basis for the greater incidence of asthma and autoimmunity in developed countries.
Two important advances in the fields of immunology and gut microbiology have emerged in recent years. First, it has been clearly demonstrated that diet has a considerable effect on the composition of the gut microbiota. Different…
kbonham | November 29, 2010Did you know that bacteria make up 90% of the cells in your body? That they make up ~5% of your mass? That they colonize you at the moment of birth and are different if you were born via c-section than if you were born naturally?
All this and more in the SITN production, "Our Microbial Organ: The good and bad bugs of the gut." And who's that handsom devil presenting (at least the first part)? Why, it's me!
Part 1: Living in a microbial world
2010 Fall Lecture 7.1: Our Microbial Organ: The Good and Bad Bugs of the Human Gut from Science in the News on Vimeo.
Part 2: Our Microbial Organ
Part 3…
kbonham | October 18, 2010This post was originally published at webeasties.wordpress.com
Have you noticed the recent spate of people coming down with terrifying bacterial infections contracted at Apple stores? Yeah, me neither. Still:
A leading Australian expert in infectious diseases says people who use display iPads and iPhones at Apple stores are risking serious infections and the company should do more to maintain hygiene[...]
"You wouldn't have hundreds of people using the same glass or cup, but theoretically if hundreds of people share the same keyboard or touch pad, then effectively that's what you're doing,"…