New research assesses the efficacy of hospital disinfectants in killing off the superbug Clostridioides difficile.

nurse rubbing her hands with disinfectant
A new study shows that disinfectants do not completely eradicate C. diff.

Clostridioides difficile (C. diff) is a bacterium that causes antibiotic resistant infections.

One of the of hospital-related deaths and a significant public health threat, C. diff caused half a million infections and almost 30,000 deaths in the United States in 2012.

Researchers often refer to it as a , which is a strain of bacteria that is resistant to several types of antibiotics.

Symptoms of C. diff include diarrhea, nausea, and fever, and in severe cases, may lead to sepsis.

One of the common ways of preventing a C. diff infection is using hand sanitizer and following handwashing guidelines when in a hospital setting. But how efficient are hospital disinfectants against this stubborn superbug?

A new study, appearing in the journal , examines the efficiency of several disinfectants against C. diff and reaches concerning conclusions.

Kevin Garey, who is a professor of pharmacy practice at the University of Houston in Texas, is the principal investigator of the study. Tasnuva Rashid, of the University of Texas School of Public Health, is the first author of the paper.

Studying C. diff and disinfectants

Rashid and team exposed five unique strains of C. diff to seven hospital disinfectants.

The researchers embedded the strains in three different biofilm types grown for 72 or 120 hours.

This is the first time that researchers have examined chemical disinfection of C. diff spores embedded in biofilms.

Prof. Garey explains that the biofilm that bacteria and other microorganisms create when they grow on a surface is akin to a "suit of armor." In the center of a biofilm, there is a spot without oxygen.

C. diff spores die when they come into with oxygen, so the oxygen-less spot is an attractive place for the anaerobic bacterium to thrive.

In the study, Rashid and colleagues made a C. diff spore germinate and replicate in the biofilm.

The researchers "compared differences between C. diff vegetative cell and spore counts, as well as biomass after exposure to disinfectants."

'No disinfectant able to completely eliminate C. diff'

"We found no disinfectant was able to completely eliminate C. diff embedded within biofilms, although we did note differences among disinfectants," reports Prof. Garey.

Specifically, Clorox, OPA, and Virex were the most effective at reducing C. diff spores, "regardless of biofilm age, ribotype, or wash conditions."

Clorox and OPA also killed total vegetative cells. The vegetative cell growth stage is the stage that causes infections.

Virex, however, did not stop vegetative cell growth. In order of efficacy at reducing C. diff biomass, Clorox and Virex were the best, followed by Nixall, OPA, and Vital oxide.

"This study helps explain why C. diff is so hard to eradicate from the environment and demonstrates the ability of these spores to be so omnipresent and self-propagate in the environment," says Prof. Garey.

The researcher also adds that according to recent estimates, about 1% of all adults over the age of 80 are likely to die of a C. diff infection, and this is regardless of whether or not they are in good health.

"Future research will be required to determine methods to eradicate this persister reservoir," conclude the authors in their paper, and Prof. Garey stresses the importance of coming up with better disinfectants.

"Clorox is the best we have but is still quite caustic to the environment. There is likely a future where we could improve upon it to make an even more superior disinfectant to fight deadly superbugs."