Stewardship / Resistance Scan for May 01, 2017

Promising new C diff drug
Antibiotics for strep throat

Novel C diff antibiotic tops vancomycin in phase 2 trial

A phase 2 trial of the novel antibiotic ridinilazole in adults with Clostridium difficile infections showed that it performed better than vancomycin, one of three drugs used to routinely treat infections, and was well tolerated, with a similar adverse event profile.

An international group of researchers, including some from Summit Therapeutics, the drug's maker, published the findings on Apr 28 in The Lancet Infectious Diseases.

From June 2014 to Aug 2015 the investigators recruited 100 patients from 33 centers in the United States and Canada, randomly assigning half to the ridinilazole group and half to receive vancomycin. Their efficacy analysis is based on 69 patients: 36 ridinilazole recipients and 33 who got vancomycin. Sustained clinical response was seen in 66.7% (24) of ridinilazole subjects compared with 42.4% (14) of those who were treated with vancomycin. Recurrence was seen in 4 (14.3%) of 28 ridinilazole patients, compared with 8 (32.8%) of 23 vancomycin patients.

The researchers also found that ridinilazole performed better than vancomycin in patients older than 75 years, those with severe disease, and those who required other antibiotics, though the differences weren't always statistically significant.

The results support further development of the drug, the team concluded.

In a related commentary in the same issue, Simon Goldenberg, MD, with King's College London, wrote that the development of new drugs to treat C diff infections is vital, and ridinilazole appears to have many qualities that make it a good candidate for further development. He noted that the study was limited by the inclusion of patients who were slightly younger than the profile of C diff patients treated in everyday practice, with few who had previous infections. "Discounting these shortcomings, it is rare for a study of an antimicrobial to show statistical superiority over the standard of care," he wrote.
Apr 28 Lancet Infect Dis abstract
Apr 28 Lancet Infect Dis commentary


Study: Prescription length for strep throat is based on history, not science  

A review published today in The Pediatric Infectious Disease Journal shows that the traditional 10-day course for antibiotics prescribed for strep throat has no basis in scientific evidence. Instead, the prescription length was determined 60 years ago, and is no more efficacious than a shorter course of treatment.

Streptococcal pharyngitis is a common diagnosis for a sore throat, and rarely can lead to serious complications, including rheumatic fever. Physicians traditionally prescribe a 10-day course of penicillin for the bacterial infection, but there are no studies that prove this prescription length is clinically valuable. Instead, it's a blanket recommendation that came out of the "penicillin boom" that followed World War II, a time when rheumatic fever was much more common in the United States.

Falling rates of rheumatic fever and the rise of non-penicillin antimicrobials should prompt clinicians to reconsider the need for 10 days of penicillin, the authors said. But, the subconscious power of the number "10" and a long clinical history will make changing prescribing patterns difficult.

"The 10-day rule appears to be an example of a more general phenomenon in clinical medicine, the fierce inertia of established usage," the authors concluded.
May 1 Pediatr Infect Dis J article

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