An Old Bug With New Strain

Over the past few years, several states have reported increased rates of Clostridium difficile-associated disease, noting more severe cases of the disease, according to the Centers for Disease Control and Prevention (CDC). The increased rates and severity of the disease may be the result of a variety of factors, including the emergence of a newly identified strain of C. difficile.

C. difficile is a spore-forming, gram-positive anaerobic bacterium that causes diarrhea and more serious intestinal conditions such as colitis. People in good health usually do not acquire C. difficile-associated diarrhea (CDAD).

Individuals who have other illnesses or conditions requiring prolonged use of antibiotics and the elderly are at greater risk of acquiring the disease. C. difficile bacteria are spread by cross contamination with infected feces. People can become infected if they touch items or surfaces that are contaminated with feces and then touch their mouth or mucous membranes. Healthcare workers can spread the bacteria from patient to patient or contaminate surfaces through hand contact.

The different life stages of C. difficile have a significant impact on the bacteriums resistance to be killed, creating serious challenges for infection control professionals (ICPs) charged with preventing the spread of this disease. To best respond to the challenges, ICPs and environmental services personnel should stay informed about C. difficile and reassess their compliance with the recommended infection control measures for addressing the bacterium.

The ability to kill C. difficile depends on the life stage of the bacterium. C. difficile vegetative (actively germinating) and the C. difficile spore are actually the same bacteria, just in different life stages. Normally fastidious in its vegetative state, C. difficile is capable of becoming a spore when environmental conditions no longer support its continued growth.

The particular state of C. difficile that is difficult to kill is the spore state.

When the organism is in a stressed environment (deprived of nutrients or exposed to dry or extreme temperatures) it goes into a spore state, or dormant state. The spore has many protective layers to help it survive, and this is why it is so difficult to kill in the spore state. When the required growth conditions return, C. difficile can return to its vegetative state. Vegetative cells can survive for at least 24 hours on inanimate surfaces, while spores can survive for up to five months.

Surrounded by an impervious cell wall or coat, these elliptical dormant spores are relatively resistant to disinfectants. At this time, there is not an existing Environmental Protective Agency (EPA)-registered disinfectant for killing C. difficile spores. There are, however, EPA-registered disinfectants with C. difficile-vegetative claims. These products, when used in accordance with label instructions, can kill C. difficile in its vegetative state.

Sole use of disinfectants with claims to kill C. difficile-vegetative will not totally prevent the transmission of the bacterium. Any surface, device or material (i.e., bed rails, restroom fixtures, etc.) that becomes contaminated with feces may serve as a reservoir for the C. difficile spores. The spores can then be transferred from patient to patient mainly via the hands of healthcare personnel who have touched a contaminated surface or item. Therefore, several steps, including frequent and thorough cleaning/disinfecting and handwashing, are necessary.

While there are no EPA-registered disinfectants for killing C. difficile spores, it is important to understand that the control of C. difficile may be achieved by implementing combined procedures, not just one individual product. Recommendations for controlling C. difficile include:

• Kill the vegetative cells on surfaces with an EPA-registered product for C. difficile vegetative. Ensure adequate cleaning and disinfection of environmental surfaces, especially items likely to be contaminated with feces and surfaces that are touched frequently.

• Prevent transfer via hands to the next patient with good hand hygiene as stated in the CDC guidelines.

• Prevent transfer via laundry with proper laundry practices. Place soiled laundry in leak-proof bags to prevent leakage onto floors or clothing. Follow laundry product label instructions for use.

• EPA-registered hospital disinfectants are recommended for general use in patient-care areas. However, the CDC mentions that bleach can be used to disinfect areas as well. While bleach has shown some success as a disinfectant against the transmission of C. difficile, it does not contain cleaning properties. Bleach is easily deactivated in the presence of soils. Remember, disinfection is not cleaning.

Just as proper cleaning and disinfection are important in preventing the spread of C. difficile, hand hygiene is no less crucial. All healthcare staff with patient or surface contact must follow proper hand-hygiene procedures.

In the event of an outbreak, staff should use soap and water for hand hygiene when caring for patients with C. difficile-associated disease; alcohol-based handrubs may not be as effective against spore-forming bacteria. If an alcohol-based handrub is used, it must be used only after soap and water hand washing.

Healthcare professionals and environmental services staff should wear gloves when entering patients rooms and during patient care. Gloves should be disposed of before exiting the room. Staff should discuss hand hygiene procedures with patients and visitors.

While studies are ongoing to identify methods and products most effective against C. difficile spores, careful physical cleaning and disinfecting for C. difficile vegetative can decrease the risk of bacterium transmission. Keeping up diligently with cleaning and hand hygiene practices will significantly reduce the risk of C. difficile transmission. 

Kay Bixler, who holds bachelor of science degrees in microbiology and chemistry, is a senior research and development project leader in antimicrobials for JohnsonDiversey Inc.