What defines severe C. difficile infection per IDSA 2021?

Severe CDI: WBC ≥15,000 cells/mm³ OR serum creatinine ≥1.5 mg/dL; Fulminant/complicated CDI: hypotension/shock, ileus, toxic megacolon; severity guides treatment choice and escalation decisions.

What first-line treatment is recommended for non-severe vs severe CDI?

Non-severe initial: fidaxomicin 200 mg BID x 10d (preferred) OR vancomycin 125 mg QID x 10d; Severe initial: vancomycin 125 mg QID; Fulminant: vancomycin 500 mg QID PO/NGT + IV metronidazole 500 mg TID.

When is fecal microbiota transplantation indicated for CDI?

FMT (SER-109 Vowst capsules approved 2023, RBX2660 Rebyota approved 2022) is indicated for 2+ recurrent CDI episodes after standard antibiotic treatment; cure rate 85-90% vs 30% for antibiotics alone after 3rd recurrence.

What is bezlotoxumab and when is it used?

Bezlotoxumab (Zinplava) is an anti-toxin B monoclonal antibody given with CDI antibiotics to prevent recurrence in high-risk patients (age >65, immunocompromised, prior CDI within 6 months); reduces recurrence by ~40% relative risk.

How should antibiotic stewardship reduce CDI?

Fluoroquinolones, clindamycin, and broad-spectrum cephalosporins are the highest CDI-risk antibiotics; antibiotic restriction and de-escalation programs reduce CDI incidence 20-50%; contact precautions and hand hygiene with soap/water (not gel) are essential.

Clostridioides Difficile Infection Severity Classification (IDSA/SHEA)

Classifies C. difficile infection (CDI) severity per IDSA/SHEA 2021 guidelines using WBC, creatinine, and clinical features to guide treatment choice (vancomycin vs fidaxomicin vs bezlotoxumab) and fecal microbiota transplant eligibility.

Weight

Height

Clinical Guidance

BMI is a screening measure of body size, not a direct measure of body fat. The standard WHO categories are underweight (<18.5), normal (18.5–24.9), overweight (25–29.9), and obese (≥30).

BMI can overestimate body fat in athletes with high muscle mass and underestimate it in older adults with low muscle mass. Interpret it alongside waist circumference and clinical context rather than as a standalone diagnosis.

⚕ Clinical Disclaimer: These calculators are for educational and reference purposes only. Always verify results with qualified clinical judgment and current clinical guidelines. Do not use as a sole basis for medical decisions.

How It Works

Each component has a specific meaning:

WBC — The wbc recorded for the patient or scenario being assessed.
Creatinine — The creatinine recorded for the patient or scenario being assessed.
Clinical features — The clinical features recorded for the patient or scenario being assessed.

Note: Interpret the c. diff severity result against the clinical thresholds and context described above.

How to Use

Enter the WBC, creatinine, clinical features for the patient or scenario you are assessing. Classifies C. difficile infection (CDI) severity per IDSA/SHEA 2021 guidelines using WBC, creatinine, and clinical features to guide treatment choice (vancomycin vs fidaxomicin vs bezlotoxumab) and fecal microbiota transplant eligibility. Use the c. diff severity result to inform your clinical assessment.

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