Metro Is So Retro – C. diff Guidelines

Written by Thomas Davis.

Spoon Feed
If you’re still reaching for metronidazole in patients with suspected or confirmed C. difficile colitis, it’s time to get up to speed with this update to the 2010 guidelines.

Why does it matter?
C. difficile colitis is a feared complication of antibiotic therapy, and community-acquired cases are on the rise.  It is notoriously difficult to treat.  The first-line drug for decades has been metronidazole.  Not any more.

1. Metro is so retro.
   Metronidazole is no longer preferred due to being less effective. Use a 10-day course of either oral vancomycin (125mg PO QID) or fidaxomicin (200mg PO BID) as first line treatment.

2. Sick as stink—literally.
   If patient has fulminant C. diff infection (hypotension, shock, ileus, megacolon), increase vancomycin dose to 500mg QID. Consider adding IV metronidazole.

3. Swollen colon.
   Ileus may not transit PO vancomycin as well in this situation. Therefore, strongly consider adding metronidazole IV 500mg q8h and consider rectal instillation of vancomycin (500mg in 100ml normal saline by retention enema).

4. Don’t test young children
   Children under 2 years of age will often have false positive testing since up to 40% of infants can be asymptomatic carriers. Unless the child has toxic megacolon, a predisposition to C. diff infection (e.g. Hirschsprung disease), or you’ve ruled out other causes of diarrhea, don’t test. 

5. Keep it simple. Don’t over test. 
   You only need to send nucleic acid amplification tests (NAAT) if you restrict testing to patients with unexplained and new onset >/= 3 unformed stools in 24 hours.  Otherwise, liberal use of the highly sensitive NAAT will pick up too many false positives. If you test willy nilly, then the IDSA recommends a more complicated algorithm to ensure a true positive.  

6. If the first test is negative, don’t check it again.
   Current tests are so sensitive that that repeat testing is not useful within 7 days—unless the patient has an obvious change in character of diarrhea.

7. What’s the definition of insanity?
   IDSA no longer recommends repeating treatment after failed initial treatment. They recommend either:
   – Get with the guidelines. Use vancomycin if metronidazole was used initially.
   – Go long! If vancomycin was used before, repeat vancomycin but taper it. 125mg qid x 10-14 days. Then BID x 1 week. Then daily x 1 week. Then every other day x 2-8 weeks.
   – Try something new. Fidaxomicin was recently FDA approved. It cleared C. diff as well as oral vancomycin but had less recurrence 25 days after treatment (29% vs 43%).
   – Third time’s a charm. For the third episode of C. diff, try another one of the above options. Or just repeat a 10-day vancomycin course and then chase it down with 20 days of rifaximin 400mg PO TID.

8. Bottoms up!
   If all else fails, offer fecal transplant for the fourth episode.

Source
Clinical Practice Guidelines for Clostridium difficile Infection in Adults and Children: 2017 Update by the Infectious Diseases Society of America (IDSA) and Society for Healthcare Epidemiology of America (SHEA).  Clin Infect Dis. 2018 Feb 15. doi: 10.1093/cid/cix1085. [Epub ahead of print]

Reviewed by Clay Smith.