New Antibiotic May Combat Resistant Bacteria

Teixobactin shows promise in early experiments, researchers say

Wednesday, January 7, 2015

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WEDNESDAY, Jan. 7, 2015 (HealthDay News) -- Laboratory researchers say they've discovered a new antibiotic that could prove valuable in fighting disease-causing bacteria that no longer respond to older, more frequently used drugs.

The new antibiotic, teixobactin, has proven effective against a number of bacterial infections that have developed resistance to existing antibiotic drugs, researchers report in Jan. 7 in the journal Nature.

Researchers have used teixobactin to cure lab mice of MRSA (methicillin-resistant Staphylococcus aureus), a bacterial infection that sickens 80,000 Americans and kills 11,000 every year, according to the U.S. Centers for Disease Control and Prevention (CDC). The new antibiotic also worked against the bacteria that causes pneumococcal pneumonia.

Cell culture tests also showed that the new drug effectively killed off drug-resistant strains of tuberculosis, anthrax and Clostridium difficile, a bacteria that causes life-threatening diarrhea and is associated with 250,000 infections and 14,000 deaths in the United States each year, according to the CDC.

"My estimate is that we will probably be in clinical trials three years from now," said the study's senior author, Kim Lewis, director of the Antimicrobial Discovery Center at Northeastern University in Boston.

Lewis said researchers are working to refine the new antibiotic and make it more effective for use in humans.

Dr. Ambreen Khalil, an infectious disease specialist at Staten Island University Hospital in New York City, said teixobactin "has the potential of being a valuable addition to a limited number of antibiotic options that are currently available."

In particular, its effectiveness against MRSA "may prove to be critically significant," Khalil said. And its potent activity against C. difficile also "makes it a promising compound at this time," she added.

Most antibiotics are created from bacteria found in the soil, but only about 1 percent of these microorganisms will grow in petri dishes in laboratories, Lewis said.

Because of this, it's become increasingly difficult to find new antibiotics in nature. The 1960s heralded the end of the initial era of antibiotic discovery, and synthetic antibiotics were unable to replace natural products, the authors said in background notes.

In the meantime, many dangerous forms of bacteria have developed resistance to antibiotics, rendering useless many first-line and even second-line antibiotic treatments. Doctors must use less effective antibiotics that are more toxic and more expensive, increasing an infected person's chances of death.

The CDC estimates that more than 2 million people are sickened every year by antibiotic-resistant infections. "Pathogens are acquiring resistance faster than we can come up with new antibiotics, and this of course is causing a human health crisis," Lewis said.

Lewis and his colleagues said they have figured out how to use soil samples to generate bacteria that normally would not grow under laboratory conditions, and then transfer colonies of these bacteria into the lab for testing as potential sources of new antibiotics.

"Essentially, we're tricking the bacteria," he said. "They don't know that something's happened to them, so they start growing and forming colonies."

A start-up company, NovoBiotic Pharmaceuticals of Cambridge, Mass., used this technology to discover a group of 25 potential new antibiotics, Lewis said. Teixobactin "is the latest and most promising" of those new leads, he said.

Teixobactin's potential effectiveness suggests that the new technology "is a promising source in general for antibiotics, and has a good chance of helping revive the field of antibiotic discovery," Lewis said.

Teixobactin kills bacteria by causing their cell walls to break down, similar to an existing antibiotic called vancomycin, the researchers said.

It also appears to attack many other growth processes at the same time, giving the researchers hope that bacteria will be unable to quickly develop resistance to the antibiotic.

"It would take so much energy for the cell to modify that I think it's unlikely resistance will appear," said study co-author Tanja Schneider, a researcher at the German Center for Infection Research at the University of Bonn in Germany.

The authors note that it took 30 years for resistance to vancomycin to appear, and they said it will probably take even longer for genetic resistance to teixobactin to emerge.

SOURCES: Kim Lewis, Ph.D., director, Antimicrobial Discovery Center, Northeastern University, Boston; Tanja Schneider, researcher, German Center for Infection Research, University of Bonn, Germany; Ambreen Khalil, M.D., infectious disease specialist, Staten Island University Hospital, New York City; Jan. 7, 2015, Nature

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