Bug vs. bug: Benign C. difficile strains keep fatal strains at bay

In a recent study, two different strains of non-toxigenic Clostridium difficile provided protection against both historic and epidemic C. difficile strains. The research was conducted by researchers at Hines VA Hospital and is published ahead of print in the journal Antimicrobial Agents and Chemotherapy.

Studies show colonization with a non-disease-causing strain of C. difficile can prevent infection by the more dangerous strains. Patients who are not colonized by benign strains may risk become infected by the harmful strains. The harmless strains occupy the same niches in the intestine that the infective strains would take if the harmless strains weren't there.

In order to determine which strains provided protection researchers first treated the hamsters with an oral antibiotic to clear their systems, then colonized with one of two strains (M3 or T7) of non-toxigenic C. difficile. The hamsters were then challenged with a colonizing dose of one of two toxigenic strains (BI1 or BI6) representing both historical and current epidemic C. difficile.

All of the hamsters colonized with either non-toxigenic strain were able to prevent infection with the historic, fatal BI1 strain. Additionally, all of the hamsters colonized with M3 were able to prevent co-infection by BI6. However, "despite 100 percent colonization with the T7 non-toxigenic strain, five of ten hamsters became co-colonized with the toxigenic strain BI6 following challenge, and four of these died," says Johnson. Overall, M3 provided better protection against the fatal tested.

"If the findings in the hamster model of C. difficile infection can be replicated in humans, then we may have a new means of protecting susceptible, high-risk —notably hospitalized patients treated with antibiotics—or preventing relapsing disease in patients who have recovered from treatment for C. difficile," says Stuart Johnson, an author of the study. Around 25 percent of first-time patients have a recurrence of the infection.

Improvements still are needed, but the hamster study suggests that they can be achieved. "Further analysis of the phase II clinical trial will be needed to help validate the findings in this study showing protection of virulent epidemic BI-associated infections with non-toxigenic C. difficile," says Johnson.

More information: A copy of the manuscript can be found online at www.asm.org/images/Communicati… s/2013/0913cdiff.pdf

add to favorites email to friend print save as pdf

Related Stories

Probiotics prevent diarrhoea related to antibiotic use

May 30, 2013

Probiotic supplements have the potential to prevent diarrhoea caused by antibiotics, according to a new Cochrane systematic review. The authors studied Clostridium difficile (C. difficile) infections in patients taking antibi ...

C. difficile hypervirulence genes identified

Sep 25, 2009

Five genetic regions have been identified that are unique to the most virulent strain of Clostridium difficile (C. difficile), the hospital superbug. Researchers writing in BioMed Central's open access journal Genome Biolog ...

Recommended for you

New York 'fully prepared' to handle Ebola case: mayor

38 minutes ago

New York's mayor said America's largest city was fully equipped to handle Ebola as authorities sought to calm fears Friday about the virus spreading, after a doctor tested positive for the disease.

Two US nurses are declared cured of Ebola

39 minutes ago

Two American nurses were declared cured of Ebola on Friday, and one was healthy enough to leave hospital and make plans to meet President Barack Obama.

Aid group: No need to isolate staff treating Ebola

1 hour ago

Doctors Without Borders insisted Friday, after one of its doctors who worked in Guinea came down with Ebola in New York, that quarantines of health workers returning from the hot zone are not necessary when ...

New York on alert over first Ebola case

1 hour ago

New York went on alert Friday as authorities sought to calm fears among the city's 8.4 million residents after a doctor tested positive for Ebola.

User comments