New drug combines with older antibiotic to treat MRSA

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When combined with an antibiotic that has been on the market for almost 20 years, a new experimental drug successfully treats the deadly infection MRSA in animals.

As reported in the journal Antimicrobial Agents and Chemotherapy, scientists combined TXA709 with cefdinir, a commonly prescribed antibiotic that has become ineffective against MRSA when used alone.

“Both drugs can be taken orally, which means they can be administered on an outpatient basis.”

“This is important because even though TXA709 is effective on its own in treating MRSA, combining it with cefdinir—used to treat a wide range of bacterial infections like strep throat, pneumonia, bronchitis, and middle ear and sinus infections—makes it even more efficacious, while also significantly reducing the potential for the MRSA bacteria to become resistant in the future,” says Daniel Pilch, associate professor of pharmacology at Rutgers University’s Robert Wood Johnson Medical School.

Scientists are racing to develop a new class of antibiotics to treat methicillin-resistant Staphylococcus aureus infections, which are responsible for 19,000 deaths annually and represent $3 billion in health care costs each year.

The threat of MRSA and other antibiotic-resistant infections has become so severe that the World Health Organization predicts that common infections and minor injuries could become life-threatening because of a lack of drug treatments available to destroy these bacterial infections.  Last month the first case in the United States of a patient with an infection resistant to all known antibiotics was reported by the US Centers for Disease Control and Prevention.

“Current standard-of-care drugs for the treatment of MRSA infections are limited,” Pilch says.  “Furthermore, resistance to these drugs is on the rise, and their clinical effectiveness is likely to diminish in the future.”

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TXA709 kills the bacteria in a unique manner unlike any other antibiotic in current clinical use, inhibiting the function of a protein, FtsZ, that is essential for the bacteria to divide and survive.  By combining TXA709 with cefdinir, a cephalosporin antibiotic that acts much like penicillin, scientists were able to lower the dosage of the new antibiotic required to eradicate the MRSA infection.

This is significant, because it decreases the potential for any drug-induced toxicity and side effects that might occur from a higher dosage.

“What is also good about this experimental treatment is that both drugs can be taken orally, which means they can be administered on an outpatient basis,” says Pilch.  “All but two of the current antibiotics being used clinically to treat MRSA need to be administered intravenously.”

Phase I clinical trials on the new antibiotic, which will assess and evaluate its safety and effectiveness in humans, are expected to begin next spring.

Source: Rutgers University