antibiotics
mikethemadbiologist | February 26, 2007When I heard that Republican Senator and presidential candidate John McCain spoke at the Discovery Institute, I was disappointed but not surprised. In March, there's going to be a report released about antibiotic resistance in bacteria. A major finding of the report: roughly 40,000 people die every year from hospital-acquired antibiotic resistant bacterial infections.
The problem of antibiotic resistance is, fundamentally, a problem of evolutionary biology. Species of bacteria which had very few resistant strains (or none at all) now contain high frequencies of resistance strains (e.g…
mikethemadbiologist | February 22, 2007Some of my fellow ScienceBloglings have written about Conservapedia's treatment of evolution. What has always puzzled me about creationists is the rather frequent denial of mutation. For example, in the section on macroevolution, titled "Is the theory of macroevolution true?"*--which should tell you what's to come right away, the entry reads:
2. Differences between organisms can be explained by known mechanisms of genetic mutation.
* Counter: There has not been enough time for mutation to generate existing biological diversity.
* Counter: There has been enough time enough…
mikethemadbiologist | February 15, 2007I've blogged before about how, for children under five, it's not the 'sexy' microbes that kill, but instead, the run of the mill ones: the bacteria that cause diarrhea and pneumonia are the culprits. One of the things I have heard a lot of recently regarding antibiotic development (and related therapies) is that we need to focus on 'non-paradigm' and non-model organisms. There's a problem with that approach:
The non-standard microbes aren't the ones causing the bulk of bacterial disease.
Oh dear.
In roaming around the International Society for Microbial Resistance website, I came across…
mikethemadbiologist | February 14, 2007Having been trained as an evolutionary biologist, I've always thought that the medical literature avoids using the word evolution: instead, words like emergence, development, spread, and acquisition are used. In PLos Biology, there's an article that quantifies what I've always suspected:
The increase in resistance of human pathogens to antimicrobial agents is one of the best-documented examples of evolution in action at the present time, and because it has direct life-and-death consequences, it provides the strongest rationale for teaching evolutionary biology as a rigorous science in high…
mikethemadbiologist | February 12, 2007Here's some very good news about MRSA (methicillin resistant Staphylococcus aureus): U.S. hospitals are beginning to implement their own versions of 'search and destroy' (italics mine):
Hospitals can stem the alarming spread of a dangerous and drug-resistant staph infection by screening new patients and keeping them quarantined, say doctors who tried this novel approach.
One model is a pilot program started in 2001 at the Pittsburgh Veterans Affairs Healthcare System, which has dramatically cut the rate of the potentially deadly germ, called methicillin-resistant Staphylococcus aureus, or…
mikethemadbiologist | February 8, 2007By way of Effect Measure, I came across this Consumer Reports article about bacterial contamination of chicken. The short version: I'm not convinced that the bacterial contamination problem has become worse--keep in mind, I'm not saying that bacterial contamination is not a problem, only that the problem has remained constant in scope.
A good comparison to the Consumer Reports ('CR') study is the National Antimicrobial Resistance Monitoring System ('NARMS') report. For almost ten years, NARMS has been collecting bacterial isolates nationwide from store-bought meat products, including…
mikethemadbiologist | January 31, 2007Methicillin resistant Staphylococcus aureus (MRSA) is a major public health threat. Currently, there are only a few antibiotics that are effective against it, and resistance is even a problem with these antibiotics. There is a potential treatment that might be effective against MRSA: heteropolymer (HP) antibody therapy.
To explain what HP antibody therapy is, I first want to give a vastly oversimplified explanation of what your immune system does when your bloodstream is infected with MRSA. The immune system, produces two molecules that attach to each other, one of which is an antibody.…
mikethemadbiologist | January 29, 2007I write often about irresponsible antibiotic use. But I want to make one thing clear: antibiotics are critical, life-saving and health-improving drugs. In the U.S., every year roughly two million people contract hospital-acquired infections (this ignores infections contracted outside the hospital). Roughly 96% don't die. Antibiotics are a major reason, if not the major reason, for why the mortality rate is so low. I'm pointing out the obvious because of an email I received (I've 'de-identified' all of the personal information):
hi, mike. i've been reading your blog on triclosan and…
mikethemadbiologist | January 24, 2007Well, kinda sorta. I'm mentioned in a UPI article about rapid diagnosis of influenza and antibiotic use. Rather than repeat the UPI story, here's the abstract (don't worry, I'll translate):
Background: Rapid influenza testing decreases antibiotic and ancillary test use in febrile children, yet its effect on the care of hospitalized adults is unexplored.We compared the clinical management of patients with influenza whose rapid antigen test result was positive (Ag+) with the management of those whose rapid antigen test result was negative or the test was not performed (Ag0).
Methods: Medical…
mikethemadbiologist | January 23, 2007Update: I was in error (long day at work). The article was published in Wired magazine
Seed Magazine, the meatworld Overlords of ScienceBlogs, has an article about Acinetobacter baumannii, a bacterium which can be resistant to virtually every antibiotic used to treat it--and in some cases, all antibiotics.
It's pretty good, although I think A. baumanii is less of a problem than MRSA, for example. It's also never been clear to me why the strains that circulate in hospitals are resistant to fewer drugs than those recovered from environmental trauma wounds (e.g., wounded soldiers). Anyway, I…
mikethemadbiologist | January 18, 2007In the developed world, shigellosis, a diahrreal disease caused by the bacterial species Shigella, typically isn't considered dangerous, even though it makes about 450,000 ill in the U.S. To shorten the length of illness and to reduce potential infection of other people, antibiotics are typically prescribed, usually cotrmoxazole or ampicillin. However, recent shigellosis outbreaks are cause for concern (italics mine):
Surveillance data for antimicrobial resistance among all S. sonnei isolates received by NARMS during 1999--2003 indicated that 80% of the isolates were resistant to ampicillin…
mikethemadbiologist | January 13, 2007The most common hospital-acquired infections in intensive care units are ventilator-associated pneumonias ('VAP'), which have mortality rates between 20-50 percent. The more quickly the appropriate antibiotic can be given to the patient, the more likely the patient is to survive. Researchers in Spain have developed a rapid technique for determining which antibiotic (or antibiotics) to use.
First, a very brief bit about VAP. These infections usually result from intubation--a tube is inserted into the the mouth, through the larynx, and into the trachea, and is hooked up to a ventilator (…
mikethemadbiologist | January 4, 2007A while back I posted about how awful it would be for the FDA to approve the use of cefquinome, an antibiotic similar to the medically important drug cefepime. I even coauthored a letter about it. Well, it turns out the IDSA wrote a letter about cefquinome too (the whole letter, in pdf). There's good and bad things about the letter. First, the bad--the IDSA proposals about what to do if cefquinome is approved:
1. Limit the marketing status to prescription only.
2. Prohibit extra-label use of the product.
3. Limit the extent of use to "low," meaning that the drug will be administered…
sporte | January 4, 2007The wind storms and heavy rains that hit Seattle recently, demonstrated why a bypass mechanism can be a helpful thing - for both bacteria and motorists.
Under the bridge on Mercer, from the Seattle Times
When the weather is nice, I bike to work. But when the weather gets bad, (I consider rain and 69 mph winds to be BAD), I take the easy way out. On the day of the big windstorm though, driving home was not so easy. A mudslide covered one of my usual paths, blocked two lanes on a very busy street, and stopped traffic well into the depths of the city.
Since we had to get to a soccer…
sporte | January 3, 2007This is the fifth part of a multipart series on antibiotic resistance in bacteria.
The previous installments:
1. A primer on antibiotic resistance: an introduction to the question of antibiotic resistance.
2. Natural vs. synthetic drugs: what is the difference between an antibiotics and synthetic drugs.
3. How do antibiotics kill bacteria? a general discussion of the pathways where antibiotics can act and one characteristic that helps some bacteria survive.
4. Are antibiotics really only made by bacteria and fungi? It depends on what you'd like to call them.
Before we go on, I think it's time…
sporte | January 2, 2007After reading Kevin C.'s question in the comments on my last antibiotic post, I decided to look into this question a bit further.
As far as I can tell, most of the commercially producted antibiotics are made by bacteria, fungi, and a bit chemistry (more on that in a moment). It appears, however, that compounds with antimicrobial properties are made by just about everything. Just to make things complicated, these molecules are sometimes called "antibiotics" in the literature and sometimes they're not.
Many of the molecules with antimicrobial activity are short peptides- chains of amino…
sporte | December 30, 2006This is multipart series on antibiotic resistance in bacteria.
Check out the previous bits:
1. A primer on antibiotic resistance
2. Natural vs. synthetic drugs
Eventually, we'll reach the ways in which bacteria develop antibiotic resistance, but before we get there, we'll spend a little more time on antibiotics themselves.
What have we learned so far?
1. Antibiotics are natural products, made by bacteria and some fungi.
We have also learned about the difference between antibiotics and synthetic drugs. There isn't always a clear distinction since chemical groups can be added to…
mikethemadbiologist | December 27, 2006Thankfully for the readers, most of the scientific literature I read doesn't make it into this blog. But one paper about a comparative drug trial had some very interesting results. In short, obesity and smoking are significant risk factors for post-operative infections.
The article, published in the NE Journal of Medicine, is a comparative study of which is the better antibiotic use to use after colorectal surgery to prevent infections: etrapenem or cefotetan. While cefotetan is typically used, etrapenem was was associated with significantly fewer post-operative complications.…
mikethemadbiologist | December 26, 2006From the archives, I'm reposting this article about MRSA and VRSA. I've made some changes because the science and medical practice have changed.
The Chicago Tribune reports that three children died from toxic shock syndrome caused by methicillin resistant Staphylococcus aureus ("MRSA"). Toxic shock syndrome is not typically associated with MRSA. What's worse is that these infections were "community-acquired" (CA-MRSA) In other words, the kids were not infected in the hospital-many staph infections are hospital acquired due to puncturing the skin barrier (e.g., catheters, IVs, surgery).…
mikethemadbiologist | December 23, 2006At a recent conference (pdf), Dr. Rebecca Roberts described how medical residents and doctors treat urinary tract infections. But first, a bit about 'empirical therapy.'
When a patient is sick it can take anywhere from 24-72 hours at a hospital with good facilities to identify what organism is causing the disease and which antibiotics will be effective against it. Empirical therapy uses the patterns of resistance (and infections) of previous cases at the hospital in conjunction with other guidelines to choose the most effective antibiotic therapy. Think of it as a highly educated guess--…