C. Diff Tx

Question 1

Describe the toxins of C. diff

Answer 1

-toxins A and B (which are particularly overexpressed in the NAP-1/027 strain that lacks a protein known as tcdC whose expression normally downregulates transcription of these toxins)

Question 2

Question 3

What are the risk factors for C. diff infection?

Answer 3

• ABX use, especially concurrently
• hospitalization, health-care facilities
• age (most common 65-84 yo)

IBD-increased with CD?

Gastric acid suppression (?)

Question 4

What ABX use is especially linked to C. diff?

Answer 4

Clindamycin

Penicillins

Cephalosporins

Fluoroquinolones

Question 5

Question 6

How is C. diff diagnosed?

Answer 6

• clinical suspicion (diarrhea after ABX use) supported by C. diff and/por toxins in stool
• ELISA for toxins A and B (limited sensitivity with frequent false negatives)

Question 7

What are the main tx options for initial C. diff diarrhea?

Answer 7

• Oral metronidazole 500 mg q8h x 10 d for mild-moderate
• oral Vanco (125 mg q6h x 10d) for severe and pregnant/lactating women
• High dose oral Vanco and IV metronidazole for complicated disease

Question 8

T or F. Rectal vanco enemas can be given in pts. with ileus, abdominal distention, and anatomic/surgical abnormalities that prevent oral ABX from reaching the colon

Answer 8

T.

Question 9

How should the 1st recurrence of C diff be tx? 2nd?

Answer 9

1st: same protocol
2nd: oral Vanco

Question 10

T or F. Metronidazole crosses the placenta and is expressed in breast milk

Answer 10

T. Dont give to either

Question 11

What are the AEs of Metronidazole?

Answer 11

• Nausea and metallic taste
• facial anomalies in infants if taken during pregnancy
• increased oral and rectal candida colonization in children if passed through breast milk
• peripheral neuropathy of extremities

Question 12

How does Fidaxomicin work?

Answer 12

It is a macrolide that is bactericidal against C. diff via inhbiitng bacterial RNA polymerases (note that there is no cross-resistance with other antimicrobials, including rifamycin due to different site of action)

Minimal/no activit against gram neg anaerobes, facultative anaerobes, and enterobacterioceae

Question 13

How well is fidaxomicin absorbed?

Answer 13

poorly; remains in the GI and eliminated in stool

Question 14

What are the AEs of fidaxomicin?

Answer 14

N/V

abdominal pain

GI bleeding

Question 15

T or F. In head to head comparison with vanco in groups at high risk for CDI recurrence, fidaxomicin provides a superior clinical response and lower incidence of recurrence

Answer 15

T.

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Question 18