Frequently Asked Questions

Information About A New Strain Of Clostridium difficile

Released July 2005

Questions and Answers

How is Clostridium difficile (C. difficile)-associated disease changing?

Over the past 2 years, several states have reported increased rates of C. difficile-associated disease, noting more severe disease and an associated increase in mortality. It is not clear at this time if the population at risk (those most susceptible to acquiring C. difficile-associated disease) is changing.

What are the possible reasons for this change in the disease?

The increased rates and/or severity of disease may be caused by changes in antibiotic use, changes in infection control practices, or the emergence of a new strain of C. difficile-associated disease with increased virulence and/or antimicrobial resistance.

Has a new strain of C. difficile been identified?

Yes, the emergence of a new strain of C. difficile-associated disease causing hospital outbreaks in several states has been reported by the Centers for Disease Control and Prevention (CDC) at scientific meetings. Publication of these data is under development.

What is unique about this new strain?

The new strain appears to be more virulent, with ability to produce greater quantities of toxins A and B. In addition, it is more resistant to the antibiotic group known as floroquinolones.

How is the new strain detected?

Like other strains of C. difficile, this new strain can be detected in the stool of infected patients by using laboratory tests that are commonly available in most hospitals. However, none of the commonly available tests differentiate between the various strains of C. difficile. Fortunately, because the control measures for outbreaks of any strain of C. difficile are similar, identification of the specific strain is not imperative for controlling outbreaks.

Is treatment of this new strain different?

The usual treatment for C. difficile-associated disease includes, if possible, stopping antibiotics being given for other purposes and/or treatment with metronidazole or vancomycin. In order to reduce selective pressure for vancomycin resistance in enterococci, current guidelines recommend the first-line use of metronidazole over vancomycin . However, recent reports suggest that the new strain may not respond as well to treatment with metronidazole despite the absence of laboratory evidence of metronidazole resistance. This may be due to increased virulence in the new strain. Depending upon the severity of the C. difficile-associated disease, metronidazole is likely to be the appropriate first-line therapy for most cases. Regardless of what therapy is used, patients should be carefully monitored to be sure they are responding to therapy and that there is no deterioration in their condition.

How does fluoroquinolone resistance affect management of this strain?

Increased fluoroquinolone resistance does not affect the management of infections caused by this strain. Fluoroquinolones have never been recommended for treatment of C. difficile-associated disease and susceptibility testing is performed only as a part of an epidemiological investigation. However, resistance to fluoroquinolones may provide the new strain with an advantage over susceptible strains to spread within healthcare facilities where these antibiotics are commonly used.

What should healthcare facilities do in response to the emergence of the new strain?

Healthcare facilities should monitor the number of C. difficile-associated disease cases and, especially if rates at the facility increase, the severity of disease and patient outcomes.

If an increase in rates or severity is observed, healthcare facilities should reassess compliance with the recommended infection control measures for known cases of C. difficile-associated disease including the following:

  • Perform hand hygiene using an alcohol-based hand rub or soap and water
    o If your institution experiences an outbreak, consider using only soap and water for hand hygiene when caring for patients with C. difficile-associated disease; alcohol-based hand rubs may not be as effective against spore-forming bacteria.
  • Contact precautions
  • Environmental cleaning and disinfection strategies.

If compliance is optimal with continued increase in rates and disease severity, review antimicrobial use to determine whether particular antimicrobials are associated with cases of C. difficile-associated disease. If assistance is needed with these measures, additional help should be sought from local or state health departments and/or local infection control experts.

What is CDC doing to address this issue?

CDC efforts include:

  • Collaborating with academic partners to study antimicrobial and other risk factors for C. difficile-associated disease for this and other strains
  • Working with industry and academic partners on novel environmental disinfection strategies
  • Assisting with outbreak investigations in several states.

Date last modified: July 22, 2005
Content source: 
Division of Healthcare Quality Promotion (DHQP)
National Center for Preparedness, Detection, and Control of Infectious Diseases