# Clinical Cases: Pneumonia

## 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
![Lobar Pneumonia CXR](image_01.png)
*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

1. **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

2. **What is the most likely causative organism based on the Gram stain?**
   - A) Staphylococcus aureus
   - B) Streptococcus pneumoniae
   - C) Haemophilus influenzae
   - D) Klebsiella pneumoniae

3. **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

4. **What are the criteria for ICU admission in severe CAP?**

5. **What is the role of procalcitonin in pneumonia management?**

### Answers

1. **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

2. **B) Streptococcus pneumoniae** - Gram-positive diplococci (lancet-shaped pairs) are characteristic of Streptococcus pneumoniae, the most common cause of CAP requiring hospitalization.

3. **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.

4. **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

5. **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

---

## Case 2: Hospital-Acquired Pneumonia

### Patient Presentation
A 72-year-old woman developed fever and increased oxygen requirements on hospital day 5. She was admitted for hip fracture repair and has been mobilizing slowly due to pain. She has a history of diabetes and chronic kidney disease. She has been receiving DVT prophylaxis and has a peripheral IV.

### Vital Signs
- Blood Pressure: 108/62 mmHg
- Heart Rate: 105 bpm
- Respiratory Rate: 26/min
- Oxygen Saturation: 88% on 4L NC (was 96% on room air yesterday)
- Temperature: 39.1°C

### Physical Examination
- General: Appears ill, somewhat confused
- Pulmonary: Decreased breath sounds at right base, coarse crackles
- Cardiovascular: Tachycardic
- Skin: Surgical incision clean

### Laboratory and Imaging
- **WBC**: 18,500/μL with 15% bands
- **Creatinine**: 2.1 mg/dL (baseline 1.5)
- **Chest X-ray**: New right lower lobe infiltrate
- **Blood cultures**: Pending
- **Sputum culture**: Pending (purulent sputum obtained)

### Clinical Image
![HAP Chest X-ray](image_02.png)
*Figure 2: Chest X-ray showing new right lower lobe infiltrate developing in a hospitalized patient, consistent with hospital-acquired pneumonia.*

**Image Source**: Educational illustration for teaching purposes.

### Questions

1. **What defines hospital-acquired pneumonia (HAP)?**
   - A) Any pneumonia in a hospitalized patient
   - B) Pneumonia occurring ≥48 hours after hospital admission, not incubating at admission
   - C) Pneumonia in a patient with recent hospitalization
   - D) Pneumonia requiring ICU care

2. **What are the most common pathogens in HAP?**
   - A) Streptococcus pneumoniae and Haemophilus influenzae
   - B) MRSA, Pseudomonas aeruginosa, and other gram-negative bacilli
   - C) Mycoplasma and Legionella
   - D) Influenza virus

3. **What is the appropriate empiric antibiotic regimen for HAP?**
   - A) Azithromycin alone
   - B) Antipseudomonal beta-lactam; add MRSA coverage if risk factors present
   - C) Fluoroquinolone alone
   - D) Ampicillin-sulbactam

4. **What are risk factors for multidrug-resistant (MDR) pathogens in HAP?**

5. **How does VAP differ from HAP in definition and management?**

### Answers

1. **B) Pneumonia occurring ≥48 hours after hospital admission, not incubating at admission** - HAP is defined as pneumonia that develops ≥48 hours after hospital admission and was not incubating at the time of admission. This distinguishes it from CAP that becomes apparent after admission.

2. **B) MRSA, Pseudomonas aeruginosa, and other gram-negative bacilli** - HAP pathogens differ from CAP:
   - Pseudomonas aeruginosa
   - MRSA
   - Klebsiella, Acinetobacter, Enterobacter
   - S. pneumoniae is less common in HAP

3. **B) Antipseudomonal beta-lactam; add MRSA coverage if risk factors present** - Empiric therapy:
   - Antipseudomonal beta-lactam (piperacillin-tazobactam, cefepime, or meropenem)
   - Add vancomycin or linezolid if MRSA risk factors present
   - Add second gram-negative agent if high risk for MDR or high mortality risk

4. **Risk factors for MDR pathogens**:
   - Prior IV antibiotic use within 90 days
   - Hospitalization >5 days before HAP onset
   - Prior MRSA infection or colonization
   - Structural lung disease (bronchiectasis, COPD)
   - High local prevalence of MRSA or resistant gram-negatives (>10-20%)
   - Septic shock
   - ARDS before HAP
   - Acute renal replacement therapy
   - Recent hospitalization (within 90 days)

5. **VAP vs. HAP**:
   - **VAP definition**: Pneumonia developing >48 hours after endotracheal intubation
   - **VAP pathogens**: Similar to HAP but higher rates of Pseudomonas and Acinetobacter
   - **VAP prevention**: HOB elevation, daily sedation interruption, oral chlorhexidine, early mobilization, VAP bundles
   - **VAP diagnosis**: Can be challenging; clinical pulmonary infection score (CPIS) may help
   - **Management**: Similar empiric coverage; strongly consider MDR coverage

---

## Case 3: Aspiration Pneumonia

### Patient Presentation
A 78-year-old man with a history of Parkinson's disease and prior stroke with residual dysphagia presents from a skilled nursing facility with fever, cough, and respiratory distress. Staff reports he had a witnessed choking episode 2 days ago during lunch. He has been coughing and short of breath since then with foul-smelling sputum.

### Vital Signs
- Blood Pressure: 95/58 mmHg
- Heart Rate: 112 bpm
- Respiratory Rate: 28/min
- Oxygen Saturation: 85% on room air
- Temperature: 39.4°C

### Physical Examination
- General: Ill-appearing, moderate respiratory distress
- HEENT: Poor dentition, unable to follow commands consistently
- Pulmonary: Decreased breath sounds right base, crackles bilaterally
- Cardiovascular: Tachycardic
- Neurologic: Resting tremor, rigidity, delayed responses

### Laboratory and Imaging
- **WBC**: 22,400/μL with left shift
- **Lactate**: 3.2 mmol/L
- **Chest X-ray**: Right lower lobe infiltrate with air-fluid level suggesting abscess
- **CT Chest**: Right lower lobe consolidation with cavity and air-fluid level

### Clinical Image
![Lung Abscess CT](image_03.png)
*Figure 3: CT scan of the chest showing a lung abscess with air-fluid level in the right lower lobe, a common complication of aspiration pneumonia.*

**Image Source**: Educational illustration for teaching purposes.

### Questions

1. **What anatomic factors explain why aspiration pneumonia commonly affects the right lower lobe?**
   - A) Right lower lobe has poorest blood supply
   - B) Right main bronchus is more vertical and wider; dependent segments affected
   - C) Right lower lobe is largest
   - D) Random distribution

2. **What pathogens are commonly involved in aspiration pneumonia?**
   - A) Streptococcus pneumoniae alone
   - B) Anaerobes (from oral flora), plus gram-negatives and gram-positives
   - C) Only aerobic bacteria
   - D) Primarily viral

3. **What antibiotic regimen is appropriate for aspiration pneumonia with suspected lung abscess?**
   - A) Azithromycin alone
   - B) Ampicillin-sulbactam or piperacillin-tazobactam or clindamycin + fluoroquinolone
   - C) Ceftriaxone alone
   - D) Vancomycin alone

4. **What is the difference between aspiration pneumonitis and aspiration pneumonia?**

5. **What interventions can reduce aspiration risk in this patient?**

### Answers

1. **B) Right main bronchus is more vertical and wider; dependent segments affected** - The right main bronchus takes off at a less acute angle than the left, and gravity directs aspirated material to dependent segments. When supine: posterior segments of upper lobes and superior segments of lower lobes. When upright: basal segments of lower lobes (more common on right).

2. **B) Anaerobes (from oral flora), plus gram-negatives and gram-positives** - Aspiration introduces oral flora:
   - Anaerobes: Peptostreptococcus, Fusobacterium, Prevotella, Bacteroides
   - Gram-positives: Streptococci
   - Gram-negatives: Enteric bacteria (especially in nursing home patients)
   - Polymicrobial infection is common

3. **B) Ampicillin-sulbactam or piperacillin-tazobactam or clindamycin + fluoroquinolone** - Coverage should include anaerobes:
   - Ampicillin-sulbactam 3g IV q6h
   - Piperacillin-tazobactam 4.5g IV q6h
   - Alternative: Clindamycin + fluoroquinolone or ceftriaxone
   - Metronidazole alone has poor activity against microaerophilic streptococci

4. **Aspiration pneumonitis vs. aspiration pneumonia**:
   - **Pneumonitis**: Chemical injury from gastric acid; acute onset; often resolves without antibiotics; may progress to ARDS
   - **Pneumonia**: Bacterial infection from aspirated oral/gastric contents; develops over hours to days; requires antibiotics
   - **Clinical distinction**: Pneumonitis presents immediately; pneumonia develops over 24-72 hours
   - If unclear, treat as infection; if witnessed aspiration with rapid improvement, may withhold antibiotics

5. **Aspiration prevention strategies**:
   - Speech therapy evaluation for dysphagia
   - Modified diet texture (thickened liquids, pureed foods)
   - Upright positioning during and after meals (30-45 minutes)
   - Supervised feeding
   - Oral hygiene to reduce bacterial load
   - Consider PEG tube if severe dysphagia (though does not eliminate aspiration risk)
   - Optimize treatment of underlying conditions (Parkinson's, stroke)

---

## Learning Points

1. **CURB-65 and PSI** help determine site of care for CAP; low scores may allow outpatient treatment.

2. **Empiric CAP treatment** should cover typical (S. pneumoniae) and atypical (Mycoplasma, Legionella) pathogens.

3. **HAP and VAP** require broader coverage including Pseudomonas and MRSA based on local resistance patterns and patient risk factors.

4. **Aspiration pneumonia** often involves anaerobes and polymicrobial infection; antibiotic coverage should include anaerobic activity.

5. **De-escalation** of antibiotics based on culture results and clinical response is important for antibiotic stewardship.