Evolutionary war between microorganisms affecting human health, IU biologist says

I found this article funny, in a black humor way. The bacteria are doing to us what we do to other forms of life.

From the point of view of some bacteria and parasites, humans exist for their benefit.

http://www.eurekalert.org/pub_releases/2015-07/iu-ewb073015.php

Public Release: 30-Jul-2015
Evolutionary war between microorganisms affecting human health, IU biologist says

Indiana University

Health experts have warned for years that the overuse of antibiotics is creating "superbugs" able to resist drugs treating infection.

But now scientists at Indiana University and elsewhere are finding evidence that an invisible war between microorganisms may also be catching humans in the crossfire.

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Bacteria aren't just evolving to resist new drugs, they are also constantly evolving due to competition with other microorganisms," said Bashey-Visser, an assistant scientist in the IU Bloomington College of Arts and Sciences' Department of Biology.

The result is that humans can be left trying to play catch-up.

The highly antibiotic-resistant bacteria MRSA, or methicillin-resistant Staphylococcus aureus, for example, has been shown to resist treatment in some cases due to competition with other microorganisms.

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The new mutant strain of MRSA in the overseas study overtook the original MRSA strain by producing a growth-inhibiting toxin. These toxins, called bacteriocins, are a common defense mechanism used by bacteria to compete against genetically similar microorganisms. However, in response to exposure to the bacteriocin, a third strain evolved resistance to the toxin and, coincidentally, to vancomycin.

This MRSA strain could resist the drug as a side effect of its evolutionary interactions within a host -- a process that differs from the more typical path where antibiotic resistance arises in direct opposition to treatment.

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"We're realizing more and more that harmful bacteria are just one part of our body's ecosystem, or 'microbiota,'" she said. "Broad-spectrum antibiotics can wipe out numerous beneficial bacteria species too -- or worse, create an unprotected space where new species come in and wreak havoc."

Evolutionary competition among microorganisms can benefit human health too, Bashey-Visser said.

"Other studies are increasingly tracing situations where one person becomes sick while another doesn't to the presence of beneficial microorganisms," she said. "These probiotics, or 'good bacteria,' prevent infection by attacking disease-causing bacteria."

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The use of less virulent bacteria to competively defeat disease-causing microorganisms is the basis of "replacement therapies," Bashey-Visser said. The process is similar to new treatments such as fecal transplants, in which a stool sample from a donor is introduced into the gastrointestinal tract of a patient through colonoscopy, which can restore a healthy microbiota. The procedure is an increasingly common treatment for life-threatening conditions such as Clostridium difficile infection, or CDI.

According to Monika Fischer, an assistant professor of clinical medicine at the IU School of Medicine in Indianapolis who established one of the first fecal transplant programs in Indiana in 2012, doctors who perform the procedure, which colonizes patients' "gut flora" with healthy microorganisms, report a cure rate of about 90 percent.

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