Results of a new study published in the journal Infection and Immunity reveal that an experimental vaccine used in animal models against the highly infectious and virulent bacterium, Clostridium difficile, has been found to be 100 percent effective.
In the study, the vaccine protected the mice and non-human primates against the purified toxins produced by C. difficile, as well as from an orogastric spore infection, a laboratory model that mimics the human disease, after only two immunizations.
"Animals that received two immunizations did not get sick or show signs of C. difficile-associated disease," says corresponding author Michele Kutzler, of Drexel University College of Medicine, Philadelphia.
The protection following just two immunizations is especially important since the time window in humans between colonization with C. difficile and the onset of disease symptoms can be a mere 10-14 days, says Kutzler.
The vaccine protects against the bacterial toxins by mustering anti-toxin neutralizing antibodies, says Kutzler.
The cost of fighting the half million C. difficile infections that occur annually in the US is estimated to be nearly $10 billion, most of which could be saved by a successful preventive vaccine, says Kutzler. Morbidity and mortality have risen over the last decade, likely due to increased prevalence of relapsing disease, and hypervirulent strains, she adds.
Treating the disease is especially difficult, as the bacterial spores persist in the hospital environment, where most infections occur. There is no standard, effective treatment for recurrent disease, but a small number of experimental fecal transplants for C. difficile have had a very high success rate, with no adverse reactions.
"Since our vaccine was safe, effective after only two immunizations, and performed exceptionally well, we feel that this success warrants further studies using human patients," says Kutzler.