Internal Medicine · Year 3 · from Internal Medicine
Case 1: Community-Acquired Pneumonia
Patient Presentation
A 68-year-old man presents with 5 days of productive cough with yellow-green sputum, fever, and progressive shortness of breath. He reports right-sided pleuritic chest pain. He is a former smoker (30 pack-years, quit 10 years ago) with a history of COPD. He lives at home independently and has not been hospitalized in the past year.
Vital Signs
- Blood Pressure: 128/78 mmHg
- Heart Rate: 98 bpm
- Respiratory Rate: 24/min
- Oxygen Saturation: 90% on room air
- Temperature: 38.8°C
Physical Examination
- General: Ill-appearing, but alert and oriented
- HEENT: No oral lesions
- Cardiovascular: Tachycardic, regular rhythm
- Pulmonary: Increased tactile fremitus and egophony at right base, crackles and bronchial breath sounds
- Extremities: No cyanosis
Laboratory and Imaging
- WBC: 16,800/μL with 88% neutrophils
- BUN: 22 mg/dL
- Creatinine: 1.0 mg/dL
- Procalcitonin: 2.4 ng/mL
- Chest X-ray: Right lower lobe consolidation with air bronchograms
- Sputum Gram stain: Gram-positive diplococci
Clinical Image
Figure 1: Chest X-ray demonstrating right lower lobe consolidation with air bronchograms consistent with bacterial community-acquired pneumonia.
Image Source: Educational illustration for teaching purposes.
Questions
- What is this patient's CURB-65 score and what does it indicate?
- A) 0 - outpatient treatment
- B) 1-2 - consider hospitalization
- C) 3-5 - ICU admission required
- D) Score not applicable to CAP
- What is the most likely causative organism based on the Gram stain?
- A) Staphylococcus aureus
- B) Streptococcus pneumoniae
- C) Haemophilus influenzae
- D) Klebsiella pneumoniae
- What is the appropriate empiric antibiotic regimen for inpatient CAP (non-ICU)?
- A) Vancomycin plus piperacillin-tazobactam
- B) Respiratory fluoroquinolone alone OR beta-lactam plus macrolide
- C) Ceftriaxone alone
- D) Metronidazole plus ciprofloxacin
- What are the criteria for ICU admission in severe CAP?
- What is the role of procalcitonin in pneumonia management?
Answers
- B) 1-2 - consider hospitalization - CURB-65 scoring:
- Confusion: 0
- Urea >7 mmol/L (BUN >19): 1 point
- Respiratory rate ≥30: 0
- Blood pressure systolic <90 or diastolic ≤60: 0
- Age ≥65: 1 point
- Total: 2 points - indicates moderate severity, hospitalization recommended
- B) Streptococcus pneumoniae - Gram-positive diplococci (lancet-shaped pairs) are characteristic of Streptococcus pneumoniae, the most common cause of CAP requiring hospitalization.
- B) Respiratory fluoroquinolone alone OR beta-lactam plus macrolide - For hospitalized non-ICU CAP:
- Option 1: Respiratory fluoroquinolone (levofloxacin or moxifloxacin) monotherapy
- Option 2: Beta-lactam (ceftriaxone, ampicillin-sulbactam, or cefotaxime) PLUS macrolide (azithromycin) Both regimens cover typical and atypical pathogens.
- Criteria for ICU admission (severe CAP):
- Major criteria (any one = ICU):
- Septic shock requiring vasopressors
- Respiratory failure requiring mechanical ventilation
- Minor criteria (≥3 = consider ICU):
- Respiratory rate ≥30
- PaO2/FiO2 ratio ≤250
- Multilobar infiltrates
- Confusion
- BUN ≥20 mg/dL
- Leukopenia (WBC <4000)
- Thrombocytopenia (platelets <100,000)
- Hypothermia (temp <36°C)
- Hypotension requiring fluid resuscitation
- Role of procalcitonin:
- Biomarker more specific for bacterial infection than WBC or CRP
- Elevated procalcitonin (>0.25 ng/mL) supports bacterial etiology
- Can guide antibiotic initiation and duration
- Low procalcitonin (<0.1 ng/mL) suggests viral infection or non-infectious cause
- Serial levels can help guide antibiotic discontinuation