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:





3 Responses

  1. Scary and interesting stuff, Afarensis, thanks for the post.

  2. The interesting thing, to me, was the way the antibiotics and the heartburn meds were working together…The antibiotics killed off all the competing bacteria and the heartburn meds modified the environment to make it safe and cozy for C. diff. The law of uninteded consequences can be scary…

  3. Um – C.difficile is a bacterium, not a virus, as it says in the second line of your first quote. You might want to correct that before some smart alec pulls you up on it. Whoops, too late…

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