Pathogens
kbonham | February 8, 2013A "potentially historic" blizzard is barreling down on us here in New England, and is poised to drop up to two feet of snow on Boston. All of the schools in the area preemptively closed, our public transit system is shutting down at 3:30pm, and trying to buy groceries last night was bedlam. The snow is just now beginning to fall. Winter in New England can be rough, especially for a California-raised boy like me. It's not just because of the snow and cold, it's also the influenza and common colds.
Source - Flickr user "Placbo"
The fact that the rate of some infections can vary by season is…
kbonham | January 15, 2013There are a lot of reasons that posts to this blog sometimes don't happen for months at a time, but one of them is that I can often get sucked down the rabbit hole that is Reddit. If you don't know about reddit yet, you may not want to click that link, but if you do know (and you're reading this blog), you may know about one of the communities (subreddits) there - a place called r/askscience. It's a forum where people can ask questions of a scientific nature (anything from "Why are pigeons so successful as an urban animal?" to "What's so special about the speed of light?"), and then actual…
kbonham | May 12, 2012No technology is inherently good or evil, it's the use of that technology that determines its value. A blade can be used in surgery to save a life, or as a weapon to take one. The ballistics that enable missiles to destroy enemies also enables the launch of communication satellites and exploration of other worlds. For quite a while, I've been reading +Jeff Jarvis' commentary on these issues in the realm of the internet. His principal argument is that regulation that aims to block technology in order to keep people safe will also block the innovation and potential benefits of that technology…
kbonham | September 27, 2011In other words, you're more likely to catch a cold from shaking their hand than to get an STI from Sitting on the same bench.
There isn't much reason to fear getting a sexually transmitted disease from naked sitters. These infections are most commonly the result of vigorous and prolonged exposure of a person's mucous membranes, the thinner and more permeable skin found in the mouth and on the genitals. If you happened to share a seat with an infected nudist, you'd be protected both by your clothes and by your epidermis, which serves as an effective barrier against pathogens all by itself.…
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 9, 2011In the wild, as I wrote about last week, some strains of commensal bacteria in mosquitoes seem to confer some resistance to infection with Plasmodium, the parasite that causes malaria in humans. Not content to wait for for nature to get around to it, researchers at Johns Hopkins University decided to see if they could nudge the process along:
Wolbachia Infections Are Virulent and Inhibit the Human Malaria Parasite Plasmodium Falciparum in Anopheles Gambiae
Wolbachia is a type of bacterium that often infects insects, including mosquitoes, and causes incredibly strong immune responses, but no…
kbonham | May 11, 2011Maryn McKenna has a typically great post about the rise and spread of a strain of multi-antibiotic resistant Staph aureus. It arose in Holland, where it spread to pigs, picked up resistance to the antibiotic tetracycline, and then jumped back into humans. Then it spread across the EU and into the US.
As is often the case, reading McKenna's blog is fascinating, but sobering.
One of the persistent mysteries about ST398 is how far it has spread in the U.S.. That's a very difficult question to answer, because no one is consistently doing the tests that would provide data. The national meat-…
kbonham | May 3, 2011[A while back, I received a question from a reader via e-mail.
Dear Beasties:
If you had a mutation in either C4 or C5 which one would be worse... I guess the question is is it more important to have the ability to opsonize or the ability to lyse cells with the MAC complex?
I could have done some digging and given a perfunctory answer, but I decided instead to ask my friend Matt Woodruff, another 3rd year grad student in my program whose lab works on compliment, if he could provide an answer and a bit of background. I think you'll agree it was the right choice.
The Compliment System
by Matt…
kbonham | March 22, 2011I feel like I've seen this movie before. A group of thieves need to gain entry to a highly secured vault. The vault door is nearly impregnable, and once inside, there are motion sensors, security cameras and laser trip lines, all of which sound the alarm. When the security guards hear what's happening, they are told to release a deadly gas into the vault, killing anyone inside. But Salmonella enterica, that charming bug responsible for all manner of unpleasantness, is a clever burglar. It has learned to live inside macrophages - cells that are usually used to destroy bugs - and uses their own…
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,…
heathero | March 2, 2011Check out this explanation in the New York Times science section of the 5 second rule. For the record, this will not stop me from eating fallen food off the floor. But that's just now I roll.
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 | January 11, 2011There's more to learn about the viruses that infect bacteria over at Discover. This time, it's Ed Yong talking about the bits of DNA that can be leftover in bacterial genomes from viral infections, and how they might actually be helping their hosts:
These captives are called cryptic prophages and they can make up a fifth of a bacterium's DNA. Their existence is puzzling. Bacteria are known for having small, streamlined genomes, yet in they have foreign and potentially harmful viral DNA loitering among their genes. Why?
To find out, Xiaoxue Wang from Texas A&M University found all nine…
kbonham | December 2, 2010(No pun intended)
This just sucks:
As cholera rampages through Haiti, some epidemiologists are warning that the country could face more than half a million cases over the coming year. Yet tracking and treating the disease is proving increasingly difficult as civil unrest grips the county.
As if Haiti hasn't already suffered enough. Vibrio cholerae, the bacterium that causes the disease is transmitted in contaminated water, and can divide rapidly in the digestive tract. The bacterium causes disease by secreting cholera toxin, a group of proteins that hitches a ride into the cell, sneaks…
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 | September 3, 2010[This post was originally published at webeasties.wordpress.com]
Antibiotics are awesome. They can be credited with saving more human life than any other invention and have been one of the best advancements in public health second only (maybe) to sanitation. But, as with all things pathogen related, the microbes are fighting back. Antibiotic resistance is on the rise, and diseases like MRSA (Methicillin-resistant Staphylococcus aureus) have been making the rounds in hospitals and causing a significant number of deaths.
Antibiotic resistance arises due to random mutation and natural selection…