Treatment for Positive EIA for Cytotoxin A and B

Diagnostic Confirmation

The American Geriatrics Society and the Infectious Diseases Society of America recommend that a positive EIA for toxins A and B confirms active CDI and warrants immediate treatment, as this indicates the presence of toxin-producing bacteria causing symptomatic disease 3, 4
EIA toxin positivity is diagnostic when combined with clinical symptoms (≥3 unformed stools in 24 hours) and represents true infection requiring treatment, with a specificity of toxin EIA ranging from 96-100% and sensitivity of 60-90% 1, 4, 5, 6

The Infectious Diseases Society of America recommends oral vancomycin 125 mg four times daily for 10 days as the preferred first-line agent for initial episode - mild to moderate disease, with clinical success rates of 81-88% at end of treatment 1, 2, 3
Severe disease is defined by white blood cell count ≥15,000 cells/mm³ OR serum creatinine ≥1.5 mg/dL, and oral vancomycin 125 mg four times daily for 10 days remains first-line therapy, with consideration of fidaxomicin 200 mg twice daily for 10 days as an alternative 3, 5, 6

Fulminant disease indicators include hypotension, shock, ileus, toxic megacolon, WBC >30,000 cells/mm³, or peritoneal signs, and treatment includes oral vancomycin 500 mg four times daily PLUS intravenous metronidazole 500 mg every 8 hours, with addition of rectal vancomycin 500 mg in 100 mL normal saline as enema every 6 hours if ileus is present 3, 4

Recurrence occurs in 18-25% of patients after initial treatment, and the Infectious Diseases Society of America recommends repeat of the same regimen used for initial episode if non-severe, or fidaxomicin 200 mg twice daily for 10 days for first recurrence due to lower subsequent recurrence rates 3, 5

High-risk patients who may benefit from fidaxomicin over vancomycin include those with age >65 years, emergency hospital admission, recent hospitalization, and elevated C-reactive protein at diagnosis 4

The Infectious Diseases Society of America recommends against using metronidazole as first-line therapy for initial CDI, as vancomycin demonstrates superior efficacy, and against repeating stool testing during the same episode or within 7 days of treatment completion 3, 6
The American Geriatrics Society recommends implementing strict hand hygiene with soap and water rather than alcohol-based sanitizers, and discontinuing inciting antibiotics whenever possible to reduce risk of treatment failure and recurrence 3, 4