New C difficile Guidelines Refine Diagnosis, Add FMT

Ricki Lewis, PhD

February 16, 2018

The Infectious Diseases Society of America and the Society for Healthcare Epidemiology of America have updated the 2010 clinical practice guidelines on Clostridium difficile infection (CDI) in adults.

The update adds recommendations for children, refines combinations and sequences of diagnostic tests, and changes antibiotic choices. It also, for the first time, includes guidance for implementing fecal microbiota transplantation (FMT). The guidelines are published in Clinical Infectious Diseases.

In the United States, CDI kills 15,000 to 30,000 people annually and costs more than $4.8 billion in hospitalizations. Although the annual incidence has remained stable since 2010, the infection still affects nearly half a million Americans a year. The fact that rates have fallen in some European nations suggests that the United States can do more to limit infection.

"We can better control this epidemic by learning how to use new treatments and diagnostics," said L. Clifford McDonald, MD, cochair of the guidelines panel, first author of the article, and associate director for science in the Division of Healthcare Quality Promotion for the Centers for Disease Control and Prevention.

Use of fluoroquinolones, cephalosporins, and clindamycin alter the microbiome in ways that increase susceptibility to CDI. Therefore, first-line treatment, according to the guidelines, is to discontinue use of these antibiotics. "We often find people get better on their own if they stop taking the offending antibiotic," McDonald said in a news release.

The new guidelines limit use of nucleic acid amplification tests (NAAT), which more than 70% of hospital laboratories use, because the tests can be too sensitive. The guidelines advise that NAAT be used only for new-onset cases in patients who are known not to have taken laxatives and who have had three or more unformed stools in a 24-hour period. If that is not the case, and the institution does not have its own criteria, then a diagnostic algorithm advises glutamate dehydrogenase testing (GDH). If that test is negative, then the common antigen immunoassay is recommended, and if that is negative, then NAAT is recommended. The GDH and toxin tests may be combined into one product.

The guidelines now recommend vancomycin or fidaxomicin as first-line treatment, instead of the previously recommended metronidazole.

In adults, vancomycin and fidaxomicin yield higher cure rates for CDI, even in mild cases. However, the guidelines state that use of metronidazole is acceptable if access to the other two antibiotics is limited, but only for mild or moderate cases. The cost of the two newer drugs may be prohibitive.

For children, the first-line antibiotic remains metronidazole, because vancomycin and fidaxomicin have not been shown to be superior in the pediatric population. The recommendations also caution against testing for CDI in children younger than 1 year who have diarrhea, because the bacteria are part of the normal microbiota in up to 65% of healthy infants (it occurs as part of the normal microbiota in 3% of healthy adults).

The new guidelines support use of FMT for patients who have had two or more episodes of CDI and have not responded to antibiotics. The FDA issued a guidance document in 2013 for FMT, but has not tested it in a standard clinical trial. Studies have shown that FMT is about 70% to 80% effective in treating CDI. Antibiotics have been shown to be 45% to 50% effective, although in one randomized trial, the results were mixed.

Probiotics are mentioned in the new guideline but are not recommended. "We tell patients that for the most part they won't hurt, but at this point we can't make a recommendation for which ones to use and specifically how to use them," McDonald said.

Recommendations for containing the spread of CDI in hospitals are unchanged from the 2010 guidelines: patients should be isolated, and gloves and gowns should be provided for healthcare workers and visitors.

The researchers have disclosed no relevant financial relationships.

Clin Inf Dis. Published online February 15, 2018. Full text

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