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Tag: resistance (page 2 of 2)

09.27.2012

resitant gonorrhea

The New Yorker magazine reports this month on the appearance of drug resistant gonorrhea. The trend is worrisome to the medical community. Even though the body can usually get rid of the infection without antibiotics, most times it can’t do so before it wreaks havoc and leaves damage. The abstract is below. Click here for the article (requires subscription).

ABSTRACT: MEDICAL DISPATCHES about the rise of drug-resistant gonorrhea. In January, 2009, a prostitute visited a clinic in Kyoto, Japan, for a routine checkup. Her lab test came back positive for gonorrhea. She was given several doses of ceftriaxone, the definitive treatment for gonorrhea, over a period of time, but her condition persisted. Now, public-health experts view the Kyoto case as something far more alarming: the emergence of a strain of gonorrhea that is resistant to the last drug available against it, and the harbinger of a sexually transmitted global epidemic. Gonorrhea is the second most commonly reported infectious disease in the U.S. Only one class of drugs, called cephalosporins—cefixime and ceftriaxone—is known to reliably treat it, and for several years resistance to cefixime has been rising. Some public-health officials predict that in five to eight years the superbug will be widespread. In the U.S., gonorrhea in general is linked to poverty and youth. Scientists have made little progress in developing a vaccine that would protect against a gonococcus infection. The primary hope for stemming the expected epidemic of resistant gonorrhea lies in persuading people to alter their behavior. Mentions Boston Medical Center and the walk-in clinic at Fenway Health, in Boston.

04.12.2012

resistant bacteria are as old as time

Inside the Lechuguilla cave

Antibiotic resistant bacteria are an increasing threat to our health care system. Because antibiotics are over-prescribed and also administered to livestock in their feed, bacteria have developed mechanisms to withstand antimicrobial drugs. As bacteria evolve to evade current antibiotics they become harder and harder to treat. While this may appear to be a problem created by modern medicine, there is evidence that the ability to develop drug resistance mechanisms is hard wired in bacteria. A group of scientist have uncovered species of drug resistant bacteria in a 4 million year old cave. From Scientific American:

But the capacity to fend off antibiotics might actually be lodged deep in bacteria’s evolutionary history. A new study has uncovered dozens of species of bacteria in a 4 million-year-old cave that harbor resistance to both natural and synthetic antibiotics.

A team of researchers descended to 400 meters in distant, untrafficked reaches of Lechuguilla Cave in New Mexico to collect samples of bacteria. Few people have entered the cave’s deepest regions since its discovery in 1986, and surface water takes thousands of years to percolate through the nearby dense Yates Formation rock down to the cave. As a consequence, the area is a prime place to study naturally occurring antibiotic resistance, noted the researchers, whose results were published online April 11 in PLoS ONE.

…

Wright and his colleagues found that of the 93 bacterial strains tested from the cave, most were resistant to more than one of the 26 different antimicrobials. And some bacteria were resistant to more than a dozen antibiotics used by doctors, such as telithromycin, ampicillin and daptomycin, which is currently a treatment of last resort to combat resistant infections. The cave bacteria were not likely to cause infection in humans, but could provide the genetic traits that confer resistance to that are.

Check out the research article on PLoS ONE.

03.09.2012

how cancers become resistant

From ScienceNOW:

The big push in cancer treatment these days is to sample a person’s tumor, test it for mutations, and give the patient a drug tailored to a genetic weak spot in the tumor. A new study suggests one reason why this targeted drug strategy doesn’t always work. A solid tumor, it turns out, is not a mass of identical cancerous cells but a mosaic of genetically different cells that aren’t captured with a single biopsy. Some of these distinct cells may be resistant to the targeted drugs, allowing a tumor to persist or grow.

The classic view of how cancer develops is that a single, normal cell accumulates mutations that eventually allow or force it to divide uncontrollably. This “clone” then grows into a tumor of identical cells, which can also sow seed cells into the bloodstream that then take root somewhere else in the body, or metastasize. The assumption that tumors grow out from a single clone has spurred a rush to find drugs that block one of the clone’s genetic weak spots. But although the strategy has resulted in some very effective drugs—Iressa for lung cancer and a new melanoma drug called Zelboraf, for example—these drugs often stop working within a year or two. One reason could be that solid tumors already harbor a few cells, or clones, with “resistance” mutations that take over when the cells targeted by the drug are wiped out.

More here.

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