• Posted April 26, 2024

Vancomycin May Be Losing Strength Against Common Deadly Infection

Clostridioides difficile (C. difficile) is a leading cause of illness and death, especially for frail and hospitalized Americans.

Now, a new study suggests that the leading antibiotic used to fight it, vancomycin, may be losing potency against this killer.

"It's an alarming development in the field of C. diff, as there are only two recommended antibiotics,"noted study co-author Dr. Kevin Garey, a professor of pharmacy practice and translational research at the University of Houston College of Pharmacy.

The second-line drug is fidaxomicin (Dificid).

"If antimicrobial resistance increases in both antibiotics, it will complicate the management of C. diff infection leading us back to a pre-antibiotic era," Garey said in a university news release.

According to the U.S. Centers for Disease Control and Prevention, in 2017 C. difficile killed about 12,800 people and sickened 223,900 more. The bacterium causes a bowel infection known as gastroenteritis, which can lead to diarrhea, abdominal pain and toxic megacolon (severe inflammation of the colon), sepsis and death. 

It's especially deadly for the frail elderly or people with weakened immune systems.

Vancomycin has long been the go-to antibiotic of choice against C. difficile, with its use jumping 54% in the past six years, according to Garey and colleagues.

But its power to fight the bacterium may be waning: In the early 2000s, vancomycin cleared up nearly 100% of C. difficile cases but more recently that cure rate has dropped to 70%, the Houston team said.

They looked at data from a multi-center study that tracked levels of resistance to vancomycin in 300 samples of C. difficile bacteria sourced from adults who'd been treated between 2016 and 2021.

Overall, 34% of C. difficile samples tested "exhibited reduced vancomycin susceptibility," the team reported recently in the journal Clinical Infectious Diseases.

This weakening of vancomycin "was associated with lower 30-day sustained clinical response and lower 14-day initial cure rates in the studied patient cohort,"noted senior study author Anne Gonzales-Luna. She's a research assistant professor of pharmacy practice and translational research at the university.

More information

Find out more about how C. difficile is treated at the CDC.

SOURCE: University of Houston College of Pharmacy, news release, April 25, 2024; Clinical Infectious Diseases