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New Antibiotics Show Effectiveness In Treating MRSA Infections

June 5, 2014
Image Caption: Staphylococcus aureus bacteria growing in a petri dish. Credit: Thinkstock.com

Lawrence LeBlond for redOrbit.com – Your Universe Online

Two separate studies published this week in the New England Journal of Medicine are paving the way for more effective treatments in deadly methicillin-resistant Staphylococcus aureus (MRSA) infections.

DALBAVANCIN

The first study comes from a team led by Helen Boucher, MD, Associate Professor of Medicine at Tufts Medical Center. That study reports on an antibiotic called dalbavancin (Dalvance) that has shown just as effective as vancomycin, which is the current standard treatment used against serious bacterial skin infections. The results of the study establishes dalbavancin as an effective therapy for MRSA infections.

Acute bacterial skin and skin-structure infections, such as MRSA, are among the most common reasons adults are hospitalized in the US today, with associated medical costs skyrocketing for infection treatment. While the number of healthcare-spread MRSA cases has been in decline in recent years, on any given day four percent of hospital patients have at least one healthcare associated infection (HAI), according to the US Centers for Disease Control and Prevention (CDC).

In 2011 there were an estimated 722,000 HAIs, of which more than 10 percent died as a result of their infections or complications as a result of an infection, according to CDC data.

Most of the infections happen to patients who are not in intensive care, meaning patients may be going in for simple day surgery and leaving with a serious infection that normal antibiotics are not going to treat.

Experts say that MRSA infections became a real problem in the healthcare system after doctors spent decades over-prescribing antibiotics. For decades, anyone with a cold or flu was placed on antibiotic treatment despite the fact these types of infections don’t typically respond to medication. Over time, the bacteria that survived such treatments reproduced and became more antibiotic-resistant and more widespread, reports CNN.

Now, MRSA infections are happening not just in hospitals, but also in schools, daycare facilities, gyms and spas, and are typically spread by close contact.

Dalvance, marketed by Durata Therapeutics, has now been approved by the US Food and Drug Administration to treat bacterial skin infections like MRSA, which has become resistant to most prescribed antibiotics. Dalvance is also the first drug labeled by the FDA as a Qualified Infectious Disease Product (QIDP). QIDP is part of a program that the regulator hopes will encourage drug companies to develop new effective drugs that will fight antibiotic-resistant infections.

According to CNN, any drug designated QIDP by the FDA gets priority attention and expedited review process. If approved, the drug also then qualifies for an additional five years of marketing exclusivity.

Dalvance was approved after two clinical trials that included 1,289 adults with MRSA infection. Adults in the trials were given Dalvance or another antibacterial drug. In the studies, Dalvance was just as effective as the traditional drug used to treat MRSA.

“Dalbavancin has a great likelihood of changing our practice in caring for patients with severe skin infections. It will now be possible to treat once a week instead of several times a day and will potentially remove the need for hospital admission and long-term intravenous catheters,” Boucher said in a statement.

Over a period of 10-14 days, patients were given either a once-weekly intravenous dose of dalbavancin or a twice daily intravenous dose of vancomycin followed by oral linezolid, along with dummy infusions or pills. Data from both trials were pooled and analysis showed that 79.7 percent of the dalbavancin group and 79.8 percent of the other group were treated successfully. In patients with MRSA infections, clinical success was seen in more than 90 percent of dalbavancin-treated patients, a little short of those treated with vancomycin-linezolid.

“The patients in our study were very ill: more than 85 percent had fever at entry and more than half had systemic inflammatory response syndrome. In addition, our patients had large infections with median areas of over 300 square centimeters. Our results establish dalbavancin as an effective therapy and prove non-inferiority of dalbavancin to vancomycin in the treatment of these serious infections,” explained Boucher.

ORITAVANCIN

In the second study, researchers led by Duke University School of Medicine discovered that a single-dose antibiotic is as effective as a twice-daily infusion given for up to 10 days.

The new drug – oritavancin – is seen as a potential treatment in what has been a key driver of antibiotic resistance: the tendency for patients to stop taking antibiotics once they begin feeling better. As a result of such practice, any surviving bacteria has a chance to become impervious to drugs designed to destroy them.

“The prolonged activity is what makes oritavancin distinctive,” said G. Ralph Corey, MD, lead author of the study. “This drug has a long half-life, which allows for a single-dose treatment.”

Corey led a three-year study of oritavancin that encompassed two large clinical trials of nearly 2,000 patients. The findings of this study will be presented to the FDA as part of the drug’s approval application.

As with the dalbavancin study, Corey’s team compared oritavancin to the typical vancomycin regimen, which was given twice daily for 10 days during the study. The team found that the single intravenous dose of oritavancin was as effective as vancomycin in shrinking the size of the lesion and reducing fever. Oritavancin also performed as well as vancomycin in reducing the area of the wound by 20 percent or more within the first 48-72 hours of treatment, and in curing the patients of infection.

“Having a single-dose drug could potentially prevent hospitalizations or reduce the amount of time patients would spend in the hospital,” Corey said.

Medicines Co., the maker of oritavancin, said the drug could be approved as early as August under the FDA’s QIDP process.

“This is a bit of a light at the end of a dismal tunnel in the development of new antibiotics,” Dr. William Schaffner, an infectious disease specialist at Vanderbilt University, who was not involved in the study, said in a statement to the Boston Globe.

Dr. Henry F. Chambers, a professor of medicine at UCSF, said in an accompanying editorial to the new research that this one-shot antibiotic infusion treatment could transform the treatment of acute bacterial infections and alter how they are managed.

“These patients could potentially just get an antibiotic and not be admitted to the hospital at all,” Chambers said in a telephone interview with the Globe’s Roni Caryn Rabin. “The big question is, how much money do the drug companies want in order to be able to do that?” he asked. “It won’t be chump change.”

Overall, there are an estimated 15 million cases of skin infection each year in the US, causing some 870,000 hospitalizations. A single dose treatment could bring these numbers down exponentially.

Oritavancin is effective because it persists in the body long after injection. Though none of the trial participants developed an allergic reaction to the drug, a serious reaction could result in an extended illness, noted Chambers.

With oritavancin, the most common side effects are headache, nausea, vomiting and diarrhea.

A downside to oritavancin is once the treatment is administered there is no way to reverse it if a patient turns out not to have a drug-resistant infection, some experts have noted.

As well, if patients are sent home after treatment is administered, there is a chance that even more serious infections could be missed by doctors, added Corey.


Source: Lawrence LeBlond for redOrbit.com - Your Universe Online



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