Key Clinical Formulas & Scores
Respiratory rate ≥22/min (1 point)
Systolic BP ≤100 mmHg (1 point)
Altered mentation (GCS <15) (1 point)
Score ≥2 = high risk for poor outcome with sepsis
Used as bedside screening tool to identify patients with suspected infection at risk for sepsis
Respiratory: PaO₂/FiO₂ <400=1, <300=2, <200=3, <100=4
Coagulation: Platelets <150=1, <100=2, <50=3, <20=4
Liver: Bilirubin 1.2-1.9=1, 2.0-5.9=2, 6.0-11.9=3, ≥12=4
Cardiovascular: MAP <70=1, dopamine ≤5 or dobutamine any=2, dopamine >5 or epi ≤0.1=3, dopamine >15 or epi >0.1=4
CNS: GCS 13-14=1, 10-12=2, 6-9=3, <6=4
Renal: Creatinine 1.2-1.9=1, 2.0-3.4=2, 3.5-4.9=3, ≥5=4
Increase ≥2 = sepsis (mortality ~10%)
Temperature >38°C or <36°C
Heart rate >90 bpm
Respiratory rate >20/min or PaCO₂ <32 mmHg
WBC >12,000 or <4,000 or >10% bands
≥2 SIRS criteria + suspected infection = sepsis (historical, replaced by qSOFA/SOFA)
Major (1 each): Septic shock requiring vasopressors, respiratory failure requiring mechanical ventilation
Minor (1 each): RR ≥30, PaO₂/FiO₂ ≤250, multilobar infiltrates, confusion/disorientation, uremia (BUN ≥20), leukopenia (<4,000), thrombocytopenia (<100,000), hypothermia (<36°C), hypotension requiring aggressive fluids
Mupirocin 2% ointment intranaris BID × 5-10 days
Chlorhexidine 4% body wash daily × 5-14 days
Oral rifampin + doxycycline or TMP-SMX (adjunct, limited evidence)
Indications: recurrent MRSA infections, pre-operative for high-risk surgeries, outbreak control, dialysis patients with recurrent bacteremia
Core Concepts
Sepsis & Septic Shock Management (Surviving Sepsis Campaign 2021)
Hour-1 Bundle: Measure lactate level, obtain blood cultures before antibiotics, administer broad-spectrum antibiotics, begin rapid crystalloid (30 mL/kg) for hypotension or lactate ≥4, start vasopressors if hypotensive during/after fluids. Reassess volume status and tissue perfusion. Source control: remove infected devices, drain abscesses. Antibiotics: start within 1 hour, empiric broad-spectrum covering likely pathogens. Narrow once culture results available. Vasopressors: norepinephrine first-line (target MAP ≥65), add vasopressin if refractory.
HIV Management
Diagnosis: 4th generation Ag/Ab test (detects p24 + antibodies), RNA PCR for confirmation. Acute retroviral syndrome: mononucleosis-like illness 2-4 weeks post-exposure. Treatment: ART for all regardless of CD4. Preferred initial regimen: Biktarvy (bictegravir/TAF/FTC) or Dolutegravir + TAF/FTC. Goals: undetectable viral load (<50 copies/mL), CD4 recovery. Opportunistic prophylaxis: CD4 <200: TMP-SMX for PJP; CD4 <100: consider MAC prophylaxis; CD4 <50: consider CMV monitoring. Post-exposure prophylaxis (PEP): start within 72 hours, continue 28 days. Pre-exposure prophylaxis (PrEP): TDF/FTC (Descovy) or injectable cabotegravir.
Antibiotic Stewardship Principles
Right drug, right dose, right duration, right route. De-escalation: narrow spectrum when culture results available. Duration: CAP 5-7 days, UTI 3-7 days (pyelonephritis 7-10), intra-abdominal 4-7 days. Avoid antibiotics for viral infections. Dose optimization: extended infusion for beta-lactams (piperacillin-tazobactam), weight-based dosing for vancomycin (AUC/MIC-guided). Combination therapy: synergy for Pseudomonas, Enterococcus, severe sepsis. Rapid diagnostics: PCR, MALDI-TOF, procalcitonin for bacterial vs viral.
Clinical Case Studies
Case 1: Septic Shock from Pneumonia
Patient: 68-year-old male, fever 39.5°C, confusion, productive cough × 3 days. BP 78/50, HR 125, RR 30, SpO₂ 86%. Lactate 5.2 mmol/L. CXR: right lower lobe consolidation. qSOFA = 3 (RR>22, SBP<100, altered mentation).
Diagnosis: Septic shock from CAP (severe — septic shock = major criterion).
Management: (1) Hour-1 bundle: 30 mL/kg crystalloid (3000 mL NS) within 3 hours. (2) Blood cultures × 2 before antibiotics. (3) Piperacillin-tazobactam 4.5g IV q6h + azithromycin 500mg IV q24h within 1 hour. (4) Norepinephrine infusion for MAP <65 despite fluids. (5) Mechanical ventilation if hypoxic. (6) ICU admission. Narrow spectrum at 48-72 hours based on cultures. Total antibiotic duration: 7 days if clinical improvement.
Case 2: Newly Diagnosed HIV
Patient: 28-year-old male, presents with oral thrush, weight loss 15 lbs × 2 months, recurrent herpes zoster. HIV Ag/Ab positive, RNA PCR 250,000 copies/mL. CD4 180 cells/µL.
Diagnosis: HIV/AIDS (CD4 <200 = AIDS-defining).
Management: (1) Start ART immediately: Biktarvy (bictegravir 50 mg/emtricitabine 200 mg/tenofovir alafenamide 25 mg) one tablet daily. (2) PJP prophylaxis: TMP-SMX DS daily (CD4 <200). (3) Screen for opportunistic infections: CMV, toxoplasma, hepatitis B/C, TB, syphilis. (4) Vaccinate: pneumococcal, hepatitis A/B, HPV, influenza (inactivated). (5) Counsel on adherence — undetectable = untransmittable (U=U). (6) Follow-up: viral load at 4 weeks, then q3 months until suppressed, then q6 months.
Case 3: Complicated UTI with ESBL E. coli
Patient: 55-year-old female, fever, flank pain, dysuria × 5 days. PMH: recurrent UTIs, recent hospitalization. UA: leukocyte esterase +, nitrites +, WBC >100. Blood cultures growing E. coli resistant to ceftriaxone (ESBL), susceptible to carbapenems.
Diagnosis: Pyelonephritis with ESBL-producing E. coli bacteremia.
Management: (1) Meropenem 1g IV q8h (carbapenem for ESBL). (2) Duration: 10-14 days for pyelonephritis with bacteremia. (3) Source control: no obstruction on imaging. (4) Follow-up cultures to confirm clearance. (5) Oral step-down: if susceptible to TMP-SMX or fluoroquinolone, may switch to complete course. (6) Evaluation for risk factors: urology referral for recurrent UTIs, renal ultrasound to exclude stones/structural abnormality.
Practice Questions
A: 3 points (RR ≥22=1, SBP ≤100=1, GCS <15=1). Score ≥2 = high risk for poor outcome — full sepsis evaluation warranted.
A: 5-7 days, provided patient is afebrile for 48-72 hours and clinically stable. IDSA/ATS guidelines recommend minimum 5 days.
A: Norepinephrine — starting dose 0.01-0.03 mcg/kg/min, titrate to MAP ≥65 mmHg. Vasopressin 0.03 units/min added as second-line if refractory. Dopamine only for bradycardic patients (arrhythmia risk).
A: CD4 <200 cells/µL. First-line: TMP-SMX DS daily. Alternatives: dapsone, atovaquone, or aerosolized pentamidine if allergic. Discontinue prophylaxis when CD4 >200 for ≥3 months on ART.
A: Carbapenems (meropenem 1g IV q8h or imipenem 500mg IV q6h). Ertapenem for non-Pseudomonas infections. Cefepime or piperacillin-tazobactam may be options for less severe infections based on susceptibility.