Question 19

College answer

Not available.

Discussion

Specific diagnostic investigations:

• Stool PCR for C.difficile toxin A or B
• Enzyme immunoassay for C.difficile GDH antigen
• Nucleic acid amplification test (NAAT) for C. difficile toxin gene
• Cell culture cytotoxicity assay
• Selective stool anaerobic culture confirming toxin-secreting C.difficile organisms

Investigations for complications of CDI:

• Blood biochemistry to look for end-organ damage, eg renal failure
• Endoscopy, looking for pseudomembranous colitis
• Colonic biopsy to confirm colitis
• CT abdomen/pelvis looking for:
  • Small bowel obstruction, bowel dilatation
  • Mural thickening and haustral fold thickening ("thumbprinting")
  • Toxic megacolon
  • Perforation and free intraperitoneal gas

Features of severe CDI:    

• Clinical features:
  • High fever, over 38.5º C
  • Toxic megacolon
  • An acute abdomen, peritonitis
  • Presence of ileus or evidence of bowel obstruction
• Biochemistry
  • WCC > 15 
  • Raised lactate
  • Acute kidney injury (Creatinine increase by 50%)
  • Albumin < 25
• Imaging:
  • Large intestine distension, colonic wall thickening, fat stranding, unexplained ascites 
• Endoscopy:
  • The finding of pseudomembranous colitis

Management

• Mild-moderate CDI, first episode:
  • Oral metronidazole
• Recurrent mild-moderate CDI:
  • First recurrence: treat in the same way as the first episode
  • Second recurrence: change to vancomycin or fidaxomicin; think about adding rifaximin
  • Third recurrence: consider a faecal microbiota transplant
  • Bezlotoxumab, a monoclonal antibody to the B toxin, is also recommended for severe and recurrent infections, particularly where the patient is immunocompromised. 
• Severe and complicated CDI:
  • Oral vancomycin  (up to 500mg qid) +/- fidaxomicin +/- rifaximin +/- bezlotoxumab
  • Vancomycin enema in case of ileus
  • Consider surgery
  • Tigecycline, fusidic acid, rifampicin are alternatives