C. diff: Q&A on one bad bug

CDC guidance can be used for education

The Centers for Disease Control and Prevention in Atlanta provides the following answers to common questions about Clostridium difficile (C. diff):

What is C. diff?

C. diff is a spore-forming, gram-positive anaerobic bacillus that produces two exotoxins: toxin A and toxin B. It is the most common cause of antibiotic-associated diarrhea (AAD). It accounts for 15% to 25% of all episodes of AAD. Clinical symptoms include watery diarrhea, fever, loss of appetite, nausea, and abdominal pain and tenderness.

What are the complications from C. diff-associated disease?

pseudomembranous colitis (PMC)
toxic megacolon
perforations of the colon
death (rarely)

Which patients are at increased risk for C. diff-associated disease?

The risk for disease increases in patients with:

antibiotic exposure
gastrointestinal surgery/manipulation
long length of stay in health care settings
a serious underlying illness
immunocompromising conditions
advanced age

What is the difference between C. diff colonization and C. diff-associated disease?

In C. diff colonization:

Patient exhibits no clinical symptoms.
Patient tests positive for C. diff organism and/ or its toxin.
Colonization is more common than C. diff-associated disease.

In C. diff disease:

Patient exhibits clinical symptoms.
Patient tests positive for the C. diff organism and/or its toxin.

Which laboratory tests commonly are used to diagnose C. diff-associated disease?

Stool culture for C. diff: This is the most sensitive test available, but the one most often associated with false-positive results due to presence of nontoxigenic strains.
Antigen detection for C. diff: These are rapid tests (< 1 hr.) that detect the presence of C. diff antigen by latex agglutination or immunochromatographic assays. They must be combined with toxin testing to verify diagnosis.
Toxin testing for C. diff: Enzyme immunoassay detects toxin A, toxin B, or both A and B. It is a same-day assay but less sensitive than the tissue culture cytotoxicity assay.

How is C. diff transmitted?

C. diff is shed in feces. Any surface, device, or material (e.g., commodes, bathing tubs, and electronic rectal thermometers) that becomes contaminated with feces may serve as a reservoir for the C. diff spores. C. diff spores are transferred to patients mainly via the hands of health care personnel who have touched a contaminated surface or item.

How is C. diff-associated disease usually treated?

In 23% of patients, C. diff-associated disease will resolve within two to three days of discontinuing the antibiotic to which the patient previously was exposed. The infection usually can be treated with an appropriate course (about 10 days) of antibiotics including metronidazole or vancomycin (administered orally). After treatment, repeat C. diff testing is not recommended if the patients’ symptoms have resolved, as patients may remain colonized.

How can C. diff be prevented in hospitals and other health care settings?

Use antibiotics judiciously.
Use contact precautions for patients with known or suspected C. diff-associated disease:

  • Place these patients in private rooms. If private rooms are not available, these patients can be placed in rooms (cohorted) with other patients with C. diff-associated disease.
  • Perform hand hygiene using either an alcohol-based hand rub or soap and water. If your institution experiences an outbreak, consider using only soap and water for hand hygiene when caring for patients with C. diff-associated disease; alcohol-based hand rubs may not be as effective against spore-forming bacteria.
  • Use gloves when entering patients’ rooms and during patient care.
  • Use gowns if soiling of clothes is likely.
  • Dedicate equipment whenever possible.
  • Continue these precautions until diarrhea ceases.

Implement an environmental cleaning and disinfection strategy:

  • Ensure adequate cleaning and disinfection of environmental surfaces and reusable devices, especially items likely to be contaminated with feces and surfaces that are touched frequently.
  • Use an Environmental Protection Agency-registered hypochlorite-based disinfectant for environmental surface disinfection after cleaning in accordance with label instructions; generic sources of hypochlorite (e.g., household chlorine bleach) also may be appropriately diluted and used. (Note: alcohol-based disinfectants are not effective against — and should not be used to disinfect environmental surfaces.)