Evolution in Action

Wow, according to the CDC a new mutated virus (actually a bacterium – afarensis) is going around.


The virus, Clostridium difficile, is particularly nasty:

“…a growing number of young, otherwise healthy Americans who are being stricken by the bacterial infection known as Clostridium difficile — or C. diff — which appears to be spreading rapidly around the country and causing unusually severe, sometimes fatal illness.”

There are two possible causes. First:

“This may well be another consequence of our use of antibiotics,” said John G. Bartlett, an infectious-disease expert at Johns Hopkins University in Baltimore. “It’s another example of an organism that all of a sudden has gotten a lot meaner and nastier.”


The antibiotics Flagyl (metronidazole) and vancomycin still cure many patients, but others develop stubborn infections like Shultz’s that take over their lives. Some resort to having their colon removed to end the debilitating diarrhea. A small but disturbingly high number have died, including an otherwise healthy pregnant woman who succumbed earlier this year in Pennsylvania after miscarrying twins.


The infection usually hits people who are taking antibiotics for other reasons, but a handful of cases have been reported among people who were taking nothing, another unexpected and troubling turn in the germ’s behavior.

The infection has long been common in hospital patients taking antibiotics. As the drugs kill off other bacteria in the digestive system, the C. diff microbe can proliferate. It spreads easily through contact with contaminated people, clothing or surfaces.


Canadian researchers, however, have found one possible culprit: popular new heartburn drugs. Patients taking proton pump inhibitors, such as Prilosec and Prevacid, are almost three times as likely to be diagnosed with C-diff , the McGill University researchers reported in the Dec. 21 issue of the Journal of the American Medical Association. And those taking another type called H2-receptor antagonists, such as Pepcid and Zantac, are twice as likely. By suppressing stomach acid, the drugs may inadvertently help the bug, the researchers said.

One of the reasons the virus is meaner and nastier:

In addition to being resistant, the dangerous C. diff strain also produces far higher levels of two toxins than do other strains, as well as a third, previously unknown toxin. That would explain why it makes people so much sicker and is more likely to kill.

Finally, an interesting epidemiological tidbit:

In the Dec. 8 issue of the New England Journal of Medicine, the CDC reported that an analysis of 187 C. diff samples found that the unusually dangerous strain that caused the Quebec cases was also involved in outbreaks at eight health care facilities in Georgia, Illinois, Maine, New Jersey, Oregon and Pennsylvania.

“This strain has somehow been able to get into hospitals widely distributed across the United States,” said Dale N. Gerding of Loyola University in Chicago, who helped conduct the analysis. “We’re not sure how.”

Abstracts can be found by following the links below:





Magnetic Bacteria

The above is a picture of Magnetospirillum gryphiswaldense a unique type of bacteriathat is magnetotactic. That is it uses the earth’s magnetic field to find suitable environmental conditions. How does it work? Well, Magnetospirillum absorb large amounts of iron to produce an oxide called magnetite. The magnetite is formed into magnetosomes which are strung out in a chain.

This raises two interesting questions. First, what are the genetics behind it? Second, how does the bacteria accomplish this? The two questions are related. Researchers, at the Max Planck Institute, first focused on identifying the part of the DNA that carried the code for magnetosome formation. They found a fragment containing about 25-30 different magnetosome genes. One gene had a product (MamJ) that was similar to proteins that control crystallization processes in bones, teeth and mussel shells among others. Once this gene was removed they discovered something interesting.

The picture on the left shows normal bacteria, the one on the right shows mutant bacteria with the Mamj gene disabled. Notice the magnetosomes form a straight chain in the normal but are clumped in the mutant. What was going on here? Researchers then used a relatively new technique called cyroelectron tomography to examine the magnetosome chain in more detail. This is what they saw:

The blue is cell membrane, the red are the magnetosomes, the green is a previously unknown filamentous structure (resembling a cytoskeleton)and the yellow is the MamJ product. Apparently, the MamJ product develops on the magnetosome and the filament and this is what allows them to form a chain. In the mutant bacteria, which lacks the MamJ, the magnetosomes clump toghether one they reach a certain size. This is fascinating, but there is an interesting evolutionary wrinkle. Some organisms, such as salmon and homing pidgeons, also orient themselves to magnetic fields. Interestingly, they also have magnetite chains in some of their tissue and may develop through similar mechanisms. I eagerly await further developments.

For more info:

Science Daily

The Press Release (where some of the pics and info for this post came from)

Magneto-Lab: Research(where some of the pics and info for this post came from)

The Research is also being published in Nature, Advanced Online Publication, November 20, 2005

Bacterial Adaptations to Cold Environments

This article from Science Daily is pretty interesting. A team of researchers from The Institute for Genomic Research have sequenced the genome of Colwellia psychrerythraea – a species of cold adapted bacteria that lives in temperatures below 5 degrees celcius (brrr).

“…these analyses offer a picture of evolution in action, as C. psychrerythraea uses subtle tweaks in common bacterial biology to adapt to its chilly environs. For instance, the bacterium taps a group of four to five genes to generate polyunsaturated fatty acids and pack those acids into cell membranes, resulting in membranes that are fluid and functional–rather than a frozen chunk of biomass–below the freezing point. The genome also possesses a number of duplicated genes important to cell membrane biosynthesis. What’s more, C. psychrerythraea dresses in layers, generating plenty of extracellular polysaccharides (sugars) that coat cell membranes.

Aside from its cellular outerwear, C. psychrerythraea generates a range of potential cold-protective compounds. One example is a family of polyesters, known as polyhydroxyalkanoate (PHA) compounds, that may also boost reserves of nitrogen and carbon, which could be in short supply in the extreme cold. The organism also engineers cold-hardy versions of ordinary enzymes found in free-living bacteria, such as enzymes that break down organic matter. C. psychrerythraea possesses genes that may break down complex compounds, including pollutants, as well.”

Lest you think this is just pure science, the analysis does have applications:

More than just marvels of nature, cold-adapted enzymes hold industrial promise, as active ingredients in coldwater detergents, clean-up for industrial contaminants, and food treatments. Psychrophiles could hold clues to microbial life on other planets, as well, such as the frozen surface of Mars or one of Jupiter’s moons, Europa.

So evolutionary theory could lead to a better way of cleaning up industrial contamination…

Deep Ocean Photosynthesis in Bacteria

This is cool.

Most bacteria use photosynthesis, powered by sunlight to create sugars for fuel. Recently, a species of bactera was discovered that uses light given off by hydrothermic vents to power the photsynthetic reaction.

From the article:

The bacteria have a sophisticated antenna system that allows them to collect the low light emanating from hydrothermal vents, the researchers explain in a report published online this week by the Proceedings of the National Academy of Sciences. This light energy is then transferred to the organism’s reaction center, where photosynthesis takes place. “This shows that photosynthesis is something that is not limited only to the very surface of our planet,” Blankenship says. “It lets you consider other places where you might find photosynthesis on Earth as well as on other planets.”

Friday Staphylococcus aureus Blogging

I think this is the one that put me in the hospital. Still can’t figure out how I caught it though.

Posted by Hello

Posted by Hello

Here is an interesting story on the subject though.

Staphylococcus aureus, a common germ that infects countless scrapes and scratches a year, is fast becoming an uncommon public health threat. Drug-resistant strains of staph known as MRSA, once confined to hospitals and nursing homes, have been turning up among pro football players in St. Louis, Marine recruits in North Carolina, inmates in Georgia prisons, gay men in Los Angeles, native Americans in Minnesota and pediatric wards in Atlanta.

“Close to one-fifth of what used to be a hospital-specific problem is now a community problem, and that’s a large number,” said Scott Fridkin of the Centers for Disease Control and Prevention. “We didn’t think it would be anywhere near that high when we started the study.”

Now to scare you a little:

Until a few years ago, reports of MRSA were so rare outside of hospitals that many doctors may have unwittingly aided its spread by treating it with antibiotics that didn’t work.

In the last few years, outbreaks of several new staph strains have been reported in dozens of states, as well as in England, France, Switzerland, Saudi Arabia, India, Australia and New Zealand. In the United States, at least two dozen people have died of MRSA pneumonia during the last two flu seasons.

Overall, health authorities have only a piecemeal picture of MRSA’s prevalence — much of it based on isolated outbreaks and limited surveillance of a few communities.

A 2002 survey by the Georgia Division of Public Health, for instance, found that nearly 600 people seeking treatment for staph infections at hospitals and clinics in the eight-county metro Atlanta area were infected by MRSA. The rate doubled in just a year, but the study was discontinued for budgetary reasons.

The Georgia survey found that 70 percent of people treated for such infections were getting antibiotics to which the microbe was already resistant — an error that gave otherwise mild infections an opportunity to fester and spread.

Fortunately, association with necrotizing faciitis is rare (only 14 cases so far -all in Los Angeles).

Part of the problem is caused by an evolutionary response to the overuse of antibiotics:

MRSA struck the St. Louis Rams in September 2003, when five linebackers who did not cover their artificial turf abrasions were infected. Investigators suspect players passed the bug to each other by sharing towels, using a whirlpool without showering, and by only sporadic hand washing. They also passed the bacteria — through contact on the field — to three San Francisco 49ers during a game in St. Louis on Sept. 14.

CDC epidemiologist Sophia Kazakova, who headed the Rams study, said the reasons for the outbreak are unclear, but the team’s heavy use of antibiotics may have been a contributing factor.

“The players in our investigation were receiving 10 times the number of anti-microbial prescriptions dispensed to the public,” she said.


In the 1940s, when modern medicine first used antibiotics, no one realized that was the beginning of an arms race between man and microbe that would rage across the medical landscape for the next 60 years.

Penicillin, introduced during World War II, greatly reduced staph as a threat in hospitals and operating rooms. But within two years, a strain of penicillin-resistant staphylococcus had emerged. By the 1950s, the germ was universally present in hospitals. And by the 1970s, it had spread to the community at large. Today, 95 percent of all staph strains in the world are resistant to penicillin.

Modern medicine fought back. And so did staph. A new class of antibiotics, led by methicillin, was introduced in the early 1950s. And within a few years, methicillin-resistant staph had emerged in hospitals and nursing homes, where the new antibiotics were most heavily used.

Today, staph is one of the leading causes of the estimated 2 million infections and 88,000 deaths among people who get an infection in a hospital. At least 55 percent of all hospital staph infections, 60 percent of infections in intensive care units and 71 percent in nursing homes are now caused by MRSA.

2.5 Billion Year Old Sulpher Eating Bactera?

Sulpher-eating Bacteria? Posted by Hello

According to a story in today’s St. Louis Post-Dispatch the above picture is of fossils dating to 2.5 billion years ago. It was found in China, by a geologist affiliated with St. Louis University, in what is believed to be the geological remnants of a black smoker chimney.