Vancomycin May Be More Effective for Treating Severe C. diff Infections

The most common hospital-associated infection in the United States is infection with the bacteria, Clostridium difficile (C. diff). The medication of choice to treat these infections has been the antibiotic, metronidazole; however, new research recently published in the Journal of the American Medical Association (JAMA) has found that mortality rates for patients with severe C. diff infections were lower when they were treated with vancomycin instead.

According to the Centers for Disease Control and Prevention (CDC), C. diff “caused almost half a million infections in the United States in 2011, and 29,000 [of those individuals who were infected] died within 30 days of the initial diagnosis.” Although the CDC has reported an 8% decrease in C. diff infections between 2011 and 2014, the infection remains a major issue, and accounts for 15% to 25% of all episodes of antibiotic-associated diarrhea in the United States. Conditions such as pseudomembranous colitis, toxic megacolon, perforations of the colon, sepsis, and even death, can occur as a result of infection and so treating infected patients with the right medications is paramount.

Past treatment guidelines for C. diff infections call for treatment with either vancomycin or metronidazole; however, for the past several decades, the medical community has prescribed metronidazole because it costs less than vancomycin and its use would limit the risk of resistance to vancomycin in other hospital-acquired infections.

"For many years the two antibiotics were considered to be equivalent in their ability to cure C. diff and prevent recurrent disease," lead author Vanessa Stevens, PhD, research assistant professor in the department of internal medicine and an investigator at the IDEAS 2.0 Center at the VA is quoted as saying in a press release on the research. "Our work and several other studies show that this isn't always the case."

To determine the effectiveness of metronidazole versus vancomycin in treating severe C. diff, Dr. Stevens and her team compared the risk of mortality after treatment for the two medications. They conducted, “the largest study to date by examining the data from more than 10,000 patients treated for [C. diff infection] through the US Department of Veterans Affairs healthcare system from 2005 to 2012.” Patients with elevated serum creatinine and white blood cell count within four days of C. diff infection diagnosis were determined to have severe C. diff infection. The researchers determined that about 35% of the cases reviewed were severe infections.

The results of the study showed that those patients with severe C. diff infections “had lower mortality rates when treated with vancomycin compared to metronidazole (15.3% versus 19.8%).” According to the researchers’ calculations, “only 25 patients with severe [C. diff infection] would need to be treated with vancomycin to prevent one death." To this point, Dr. Stevens is quoted in the press release as stating, “That is a powerful, positive outcome for our patient's well-being;" however, she cautioned that the researchers still do not understand how the choice of antibiotic affects mortality rates.

Because the study was observational, cause and effect of one drug over another was not proven. In addition, the authors note that the majority of patients included in the study were male; “however, past studies show that the C. diff treatment outcomes for men and women were similar.”

More research is needed to show the difference in antibiotic treatment for mild to moderate cases.