C. difficile, which infects a half-million Americans each year and kills 14,000, can spread quickly among patients. Some strains are becoming more virulent.
A vaccine "has broad public health implications for people in institutions," said Joseph Rappold, a trauma and critical-care surgeon who is leading the trial at Temple.
De Bruyn said the vaccine is also of "great importance" to Sanofi Pasteur, a subsidiary of Paris-based Sanofi, and is "designated as a flagship program."
Sanofi is the only company, he said, with a C. difficile vaccine in a Phase III trial. However, Pfizer and Valneva also are testing vaccines against the intestinal disease, and a group of European scientists announced late last year that they planned to develop an oral vaccine.
Little information is publicly available about earlier testing of the Sanofi Pasteur vaccine, and De Bruyn declined to expound, saying Sanofi plans to publish Phase II data in May. Early testing of the injection was begun by Acambis P.L.C., which Sanofi acquired in 2008.
De Bruyn referred a reporter to three studies that showed the vaccine did not present major safety concerns and caused appropriate immune responses in humans and hamsters. It prevented death and diarrhea in hamsters. Sanofi says that the FDA, which has seen more data, fast-tracked the vaccine in 2010. De Bruyn also said that study investigators are allowed to tell potential participants more about the vaccine's history than he can tell a reporter.
The company's investment in the trial, De Bruyn said, is proof of its enthusiasm for the vaccine's potential. The international scope of the study "speaks to our global ambition for this product," he said.
The vaccine targets the two primary toxins produced by C. difficile, not the bacterium itself.
Most efforts to combat C. difficile, De Bruyn said, have focused on changing hospital procedures or the care environment. A vaccine would be the first attempt to provide "personal protection."
C. difficile can spread among patients, but it also is present in the gut of some people without symptoms. It becomes dangerous when antibiotics kill off some of the normal bacteria that keep it in check. "You need that disruption of normal flora for the disease to take hold," De Bruyn said.
Overall, the trial is seeking people 50 or older who are planning a hospital stay or have been hospitalized at least twice and received systemic antibiotics in the last year.
Temple is being more restrictive, Rappold said, and is recruiting only patients scheduled for surgery. He has concentrated his efforts on patients who are planning orthopedic, spine, or head and neck procedures at Temple.
Having begun recruiting in December, Temple is in the process of obtaining consents from a handful. No one has gotten the vaccine yet, Rappold said.
De Bruyn estimated that the trial will take 41/2 years. Several hundred patients, he said, are currently participating.