Virulent Strain of C difficile on the Rise in Hospital and Community Settings

Kristina Rebelo

November 04, 2009

November 4, 2009 (San Diego, California) — New variants and new strains of Clostridium difficile that have increased virulence and decreased response to metronidazole therapy are becoming more prevalent, not only in hospital settings, but also in the community where cases are showing up in nonelderly populations. A significant number of these cases occurred in patients with no recent antibiotic use or hospitalizations, according to a population-based study released here in a poster presentation at the American College of Gastroenterology 2009 Annual Scientific Meeting.

"This is thought to be a combination of factors: older population; a broader use of antibiotics, particularly some of the newer broad-spectrum antibiotics; and a new, more virulent strain of [C difficile]," Darrell S. Pardi, MD, FACG, associate professor of medicine, Division of Gastroenterology and Hepatology, at the Mayo Clinic in Rochester, Minnesota, and senior author on the study, told Medscape Gastroenterology.

The study, based on the Rochester Epidemiological Project (Olmsted County, Minnesota), looked at C difficile infections from 1991 to 2005. Researchers found that of 385 definite cases, 192 were hospital-acquired (35 of these were nursing home residents), with a median age of 72 years (range, 1 month to 99 years); 60% were female. Of the total, 41% (158 of 385) were community-acquired, with a median age of 50 years (range, 1 to 102 years); 75% were female.

Researchers found that 35% of the hospital-acquired cases were considered severe, as were 22% of community-acquired cases. "By definition and according to IDSA [Infectious Diseases Society of America] guidelines, the community-acquired group had symptoms before they were hospitalized or within 48 hours of admission, while the hospital-acquired group became symptomatic 48 hours or more after admission," Dr. Pardi explained.

In the community-acquired group, 78% had used antibiotics within the previous 90 days; in the hospital-acquired group, 94% had. "A significant proportion of patients, especially [those with community-acquired infections], did not have traditional risk factors for [C difficile infection], such as recent antibiotic exposure," stressed Dr. Pardi. "Studies only focusing on hospital-acquired infections will miss an important subset of patients and tend to overemphasize older patients with more severe infection. Treating physicians need to think about C difficile infection in patients with diarrhea and cramps, even among their outpatients who may not have had an antibiotic exposure."

Dr. Pardi added that 40% of the community-acquired group needed to be hospitalized so that the C difficile could be managed. The most common first-line drug administered in both groups was metronidazole. Metronidazole failure and C difficile recurrence were also similar in both groups.

Brooks D. Cash, MD, FACP, FACG, CDR, MC, USN, said that "many of us are aware that in the last 5 to 10 years, there has been an epidemic of C difficile colitis occurring in this country. Currently, we're seeing more cases and more severe cases," he told Medscape Gastroenterology in an interview. Dr. Cash is chief of the Gastroenterology Division and Colon Health Initiative and associate professor of medicine at the Uniformed Services University of Health Sciences, National Naval Medical Center, in Bethesda, Maryland; and integrated chief of medicine, staff gastroenterologist at Walter Reed Army Medical Center in Washington, DC.

"This study brings more interest to the subject," Dr. Cash noted. "We test outpatients if they come in with a complaint of chronic diarrhea for C difficile and we're finding more — although it's hard to quantify. Some cases are proving more difficult to treat with the resistant strains that are emerging. We're not sure where they're coming from, either. Maybe it's overuse of antibiotics or undertreatment, where patients aren't taking their full course of antibiotics, or it could even be a novel change of the bacteria that is occurring."

"This is something clinicians need to have increased vigilance for, not just gastroenterologists," he concluded.

This study was partially funded by ViroPharma, a firm that markets and sells Vancocin HCl. Dr. Pardi and Dr. Cash have disclosed no relevant financial relationships.

American College of Gastroenterology (ACG) 2009 Annual Scientific Meeting: Abstract 27. Presented October 25, 2009.

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