NEW YORK (Reuters Health) – Patients with a history of recurrent Clostridium difficile infection upon reexposure to antibiotics might benefit from prophylactic vancomycin during subsequent antibiotic exposures, a new report suggests.

Study coauthor Dr. Alex Carignan, of the Universite de Sherbrooke in Quebec, described this hypothetical but typical case to Reuters Health in an email.

Mrs. Jones, who is 73 (the mean age of patients receiving vancomycin prophylaxis in the study), had an episode of C. difficile infection (CDI) two years ago, plus a relapse. She is now hospitalized for community-acquired pneumonia and is receiving moxifloxacin for her pneumonia. Mrs. Jones is clearly at risk of recurrent CDI, given her age and multiple past CDI episodes.

The study’s goal, Carignan explained, was to find out whether, if given concomitantly with antibiotics targeting another infection, vancomycin might prevent another CDI relapse in a patient like Mrs. Jones.

“These results are reassuring, given that several clinicians have adopted this practice, despite the limited supporting data so far,” Carignan said.

This practice also has a very low cost for hospitals, because oral vancomycin can be formulated in a hospital pharmacy, he added. Further, vancomycin has limited systemic absorption, which minimizes adverse effects.

For their retrospective study, researchers at two tertiary-care centers in Quebec, Canada, reviewed data on 551 adults with a history of CDI who were subsequently reexposed to antibiotics for other indications, including 227 who received vancomycin prophylaxis.

Recurrence occurred after exposure to antibiotics in 181 patients (32.9%), the authors reported online in the American Journal of Gastroenterology.

Oral vancomycin prophylaxis decreased the risk of recurrence, but only in patients with at least one CDI relapse in the past (AHR, 0.47; 95% CI, 0.32-0.69; P<0.0001).

“It’s good to have evidence supporting what some physicians are already doing with high-risk patients,” Dr. Susan Bleasdale, a spokesperson for the Infectious Diseases Society of America and medical director for infection control at the University of Illinois at Chicago, told Reuters Health by email.

It’s not clear why vancomycin was ineffective in patients who had not previously experienced at least one CDI relapse. The researchers suggest the reason “could be related to differences in anti-toxin A antibody titers, interleukin-8 levels, extent of gut flora alterations, or other factors involved in the pathogenesis of relapse during the natural history of recurrent CDI.”

“(W)ith respect to recurrent CDI, the effects of vancomycin on C. difficile eradication and reduction of cytotoxin production outweigh its negative impact on the gut flora,” the authors concluded.

They added, however, that in the context of secondary prophylaxis, where C. difficile load is minimal, a lower vancomycin dosage, such as 125 mg once or twice daily, might remain effective, while minimizing disruption of normal flora, but that dosage would require further study. (The most common vancomycin dosage in this study was 125 mg four times a day.)