Infectious Disease and Sepsis Calculators

qSOFA (Quick SOFA) is a rapid bedside screen for suspected infection-related organ dysfunction: respiratory rate ≥22/min (1 point), altered mentation (1 point), systolic BP ≤100 mmHg (1 point). A score ≥2 identifies patients at high risk for poor outcomes and prompts full SOFA assessment. Per Sepsis-3 definitions, sepsis is defined as a SOFA increase ≥2 points from baseline in the setting of suspected infection. qSOFA is a prompt to escalate — not a diagnostic criterion for sepsis.

SIRS (Systemic Inflammatory Response Syndrome) requires ≥2 of: temperature >38°C or <36°C, HR >90 bpm, RR >20 or PaCO₂ <32, WBC >12,000 or <4,000 or >10% bands. SIRS-based sepsis definitions (Sepsis-1/2) were replaced by Sepsis-3 in 2016 because SIRS is non-specific — it can be triggered by surgery, trauma, pancreatitis, or any physiological stress. Sepsis-3 requires organ dysfunction (SOFA ≥2) plus suspected infection, improving specificity without sacrificing sensitivity.

Vancomycin is dosed based on actual body weight and renal function. Standard dosing: 15–20 mg/kg every 8–12 hours (adjusted for eGFR). AUC/MIC-guided monitoring (target AUC 400–600 mg·h/L) is now recommended over trough-only monitoring per 2020 ASHP/IDSA/SIDP guidelines. Bayesian pharmacokinetic programs using two levels (early and late in the dosing interval) provide the most accurate AUC estimation. Trough-only monitoring (target 15–20 mg/L for serious infections) is acceptable when AUC tools are unavailable.

The Centor score estimates streptococcal pharyngitis probability: tonsillar exudates (+1), tender anterior cervical lymphadenopathy (+1), absence of cough (+1), fever >38°C (+1); age 3–14 (+1), age >45 (−1). Score ≤0: no testing or antibiotics; 1: no testing or antibiotics; 2–3: throat culture or rapid strep test; 4–5: empiric antibiotics may be considered. The modified McIsaac score (which adds age) is widely used. Group A strep causes only ~10% of adult pharyngitis — avoid routine antibiotic use without testing.

Surviving Sepsis Campaign guidelines recommend an initial MAP target of ≥65 mmHg in septic shock. Higher MAP targets (≥75–80 mmHg) may benefit patients with chronic hypertension or chronic kidney disease, though the SEPSISPAM trial showed no overall mortality benefit at 80–85 mmHg versus 65–70 mmHg. Vasopressor choice: norepinephrine is first-line; vasopressin (0.03 U/min) can be added to reduce norepinephrine dose; dopamine is reserved for selected patients with bradycardia.

Renal function is critical for dosing renally-cleared antimicrobials. Key thresholds: vancomycin intervals extend with declining eGFR; piperacillin-tazobactam dose is reduced when eGFR <40; meropenem halved at eGFR <30; nitrofurantoin is contraindicated at eGFR <30 (ineffective and toxic); levofloxacin dose reduced at eGFR <50; aminoglycosides require significant adjustment and careful monitoring below eGFR 60. Use Cockcroft-Gault creatinine clearance (not CKD-EPI) for drug dosing decisions.