SHEA 2009: Common Hand-Hygiene Products Ineffective at Killing Clostridium difficile

Kristina Rebelo

March 23, 2009

March 23, 2009 (San Diego, California) — Treating physicians and other healthcare workers should not rely on claims that antimicrobial products can rid their hands of the spore-forming bacterium Clostridium difficile and should always wear gloves when caring for an infected patient, according to a study presented here at the Society for Healthcare Epidemiology of America Annual Scientific Meeting.

C. difficile is responsible for a variety of diseases. The noninfectious form, called a spore, can survive in hospitals, nursing homes, extended-care facilities, and newborns' nurseries. The spores cannot cause infection, but when they are ingested, they transform into the active virulent form. In severe cases, C. difficile can cause critical illness and death in elderly or immunocompromised patients.

Studies have found spores on hospital items such as over-bed tables, side curtains, lab coats, scrubs, plants and cut flowers, computer keyboards (especially computers on wheels), bedpans, furniture, toilet seats, linens, telephones, stethoscopes, jewelry, diaper pails, and under fingernails; even physician's neck ties can be contaminated with C. difficile.

C. difficile Is Sticky, Similar to Anthrax Spores

Dr. Dale Gerding

Senior author and presenter Dale Gerding, MD, associate chief of staff research and development coordinator at Edward Hines Jr. VA Hospital, in Hines, Illinois, said that, similar to anthrax spores, C. difficile spores have an exosporium that confers a particular adherence — sticky chains of protein-containing substances — and they stick on hands.

"The manufacturers' claims of removing spores need to be looked at carefully, along with the patentability in this area," cautioned Dr. Gerding. "You can choose any bacterial or hand-hygiene product and they all have about the same ability to remove spores; none get more than 90% of the spores off the hands."

To test the issue, Dr. Gerding and colleagues assessed several commercially available hand washes for C. difficile spore removal.

Approximately 1 x 106 spores of nontoxigenic C. difficile (REA type T7) were inoculated onto the palms of reliable volunteers (most recruited from the hospital), said Dr. Gerding, and a modification of the American Society for Testing and Materials (ASTM) E1174 method was used to evaluate C. difficile spore removal. At least 3 volunteers performed a 15-second wash followed by a 15-second rinse for each of the products being tested.

Dr. Gerding said that the products in their study represented a wide range of commercially available cleaner chemistries — from traditional soap to synthetic surfactants.

Products tested included a 4% chlorhexidine gluconate (CHG) hand wash, a 0.3% triclosan antimicrobial hand wash, a nonantimicrobial hand wash, and a nonantimicrobial body wash. A heavy-duty hand cleaner used for printer's ink and other stubborn stains and tap water were used as controls. Log10 reductions (LR) from baseline were calculated for each product, and statistical analysis was conducted using a 1-way analysis of variance and post hoc analysis (P < .05).

At the end of testing, all products achieved a LR of only about 1 log10 within a 0.45 log10 range. The study found that tap water achieved the lowest LR (0.76), followed by the 4% CHG antimicrobial hand wash (0.77), the nonantimicrobial hand wash (0.78), the nonantimicrobial body wash (0.86), and the 0.3% triclosan antimicrobial hand wash (0.99). The heavy-duty printer's ink hand cleaner achieved the highest LR (1.21).

Heavy-Duty Hand Cleaner Cleaned Up

"Statistically, all the product performances were equivalent, except for the heavy-duty hand cleaner, which was statistically superior," Dr. Gerding said. "Removing spores is proving to be a much bigger challenge than anyone thought."

The investigators concluded that care should be taken in assessing C. difficile spore claims from hand-hygiene manufacturers, which might not be supported by scientific evidence.

These results reinforce the need for contact precautions, including gloves, when caring for a C.  difficile–infected patient, Dr. Gerding noted. These results also stress the importance of environmental cleaning and disinfection to reduce environmental spore burden.

Donald M. Dumford III, MD, a third-year resident in internal medicine from the University Hospitals of Cleveland, in Ohio, who was on the same panel as Dr. Gerding, presented his own C. difficile study on the role of asymptomatic carriers of C. difficile on patients with spinal cord injury. He told Medscape Infectious Diseases after the session that he was surprised that diligent hand washing only removed about 90% of the spores.

"I was expecting to see 95% to 98%, so even with optimal hand washing, we can pass on C. difficile," Dr. Dumford said. "And I was surprised, too, that there was no superior product. Healthcare workers cannot use heavy-duty cleaners on their hands every time they wash. Their hands would become reddened and the inflammation would make them all the more susceptible to C. difficile. What we have to do now is find new products to take spores off of hands."

Dr. Gerding has received grant and research support from Gojo Industries Inc and research funding from the US Department of Veteran Affairs. Dr. Dumford has disclosed no relevant financial relationships.

Society for Healthcare Epidemiology of America (SHEA) 19th Annual Scientific Meeting: Abstract 43. Presented March 20, 2009.