Case study in emergency medicine

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Topic pneumonia

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What is the most likely diagnosis

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pneumonia chest X-ray consolidation

This diagnostic image is a posterior-anterior (PA) view chest X-ray demonstrating multifocal pneumonia with prominent consolidations. In the right lung, there is dense consolidation involving the upper lobe, characterized by increased radiopacity that obscures the regional vascular markings. Patchy, ill-defined airspace opacities are also visible extending into the right lower lobe. The left lung field reveals significant consolidation primarily localized within the lower lobe, partially obscuring the left hemidiaphragm silhouette. The cardiac silhouette appears normal in size, and the trachea is midline. The visual findings are consistent with severe pulmonary infection, such as atypical pneumonia (e.g., Legionella species). This clinical imaging serves as an educational example of multifocal bacterial consolidation and its radiographic distribution in the context of acute respiratory distress and sepsis.

This diagnostic image is a posterior-anterior (PA) view chest X-ray demonstrating multifocal pneumonia with prominent consolidations. In the right lung, there is dense consolidation involving the upper lobe, characterized by increased radiopacity that obscures the regional vascular markings. Patchy, ill-defined airspace opacities are also visible extending into the right lower lobe. The left lung field reveals significant consolidation primarily localized within the lower lobe, partially obscuring the left hemidiaphragm silhouette. The cardiac silhouette appears normal in size, and the trachea is midline. The visual findings are consistent with severe pulmonary infection, such as atypical pneumonia (e.g., Legionella species). This clinical imaging serves as an educational example of multifocal bacterial consolidation and its radiographic distribution in the context of acute respiratory distress and sepsis.

A frontal (anteroposterior) chest X-ray demonstrating clinical signs of pneumonia. A prominent blue arrow indicates a large area of increased opacity in the right lower lung field, suggestive of lobar consolidation or a dense pulmonary infiltrate. The opacity is heterogeneous with ill-defined borders, blending into the surrounding parenchyma. Beyond the focal area, there are diffuse bilateral reticulonodular interstitial markings, more pronounced in the mid and lower lung zones. The right costophrenic angle is relatively sharp, while the left shows mild blunting. Several medical devices are present: multiple radiopaque ECG leads/electrodes are positioned on the upper chest and shoulders, and a radiopaque enteric tube (nasogastric or feeding tube) is visible traversing the mediastinum toward the stomach. The image illustrates typical radiological findings of an infectious process in an acute clinical setting, highlighting focal consolidation against a background of generalized pulmonary congestion or inflammation.

A frontal (anteroposterior) chest X-ray demonstrating clinical signs of pneumonia. A prominent blue arrow indicates a large area of increased opacity in the right lower lung field, suggestive of lobar consolidation or a dense pulmonary infiltrate. The opacity is heterogeneous with ill-defined borders, blending into the surrounding parenchyma. Beyond the focal area, there are diffuse bilateral reticulonodular interstitial markings, more pronounced in the mid and lower lung zones. The right costophrenic angle is relatively sharp, while the left shows mild blunting. Several medical devices are present: multiple radiopaque ECG leads/electrodes are positioned on the upper chest and shoulders, and a radiopaque enteric tube (nasogastric or feeding tube) is visible traversing the mediastinum toward the stomach. The image illustrates typical radiological findings of an infectious process in an acute clinical setting, highlighting focal consolidation against a background of generalized pulmonary congestion or inflammation.

This diagnostic image is a posterior-anterior (PA) chest X-ray demonstrating common radiographic features of focal pneumonia. The primary finding is located in the right lung field, where patchy airspace opacities and an area of pulmonary consolidation are visible, highlighted by a blue arrow. The consolidation is characterized by increased density that obscures the underlying pulmonary vasculature, consistent with fluid or inflammatory exudate replacing air in the alveoli. The left lung field appears clear without similar focal opacities. The mediastinal contours, including the cardiac silhouette and trachea, are within normal limits. The costophrenic angles are sharp, suggesting the absence of significant pleural effusion. Bony structures, including the ribs, clavicles, and vertebrae, as well as the surrounding soft tissues, show no acute abnormalities. This image serves as a clinical example of localized infectious process, such as community-acquired pneumonia, in an adult patient.

This diagnostic image is a posterior-anterior (PA) chest X-ray demonstrating common radiographic features of focal pneumonia. The primary finding is located in the right lung field, where patchy airspace opacities and an area of pulmonary consolidation are visible, highlighted by a blue arrow. The consolidation is characterized by increased density that obscures the underlying pulmonary vasculature, consistent with fluid or inflammatory exudate replacing air in the alveoli. The left lung field appears clear without similar focal opacities. The mediastinal contours, including the cardiac silhouette and trachea, are within normal limits. The costophrenic angles are sharp, suggesting the absence of significant pleural effusion. Bony structures, including the ribs, clavicles, and vertebrae, as well as the surrounding soft tissues, show no acute abnormalities. This image serves as a clinical example of localized infectious process, such as community-acquired pneumonia, in an adult patient.

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Emergency Medicine Case Study: Pneumonia


THE CASE

Patient: 68-year-old male Setting: Emergency Department, presented at 9 PM
Chief Complaint: "I've had fever and a bad cough for 3 days, and now I can't breathe well."

History of Present Illness

A 68-year-old retired farmer with a history of COPD and type 2 diabetes presents with:
  • 3 days of worsening productive cough with rust-colored sputum
  • High fever with shaking chills (T 39.6°C at home)
  • Acute onset right-sided pleuritic chest pain (sharp, worse with breathing)
  • Progressive dyspnea - now short of breath at rest
  • No nausea, vomiting, or diarrhea
  • No recent hospitalization or travel
PMH: COPD (on inhaled LABA/ICS), Type 2 DM (metformin), HTN Medications: Tiotropium, salmeterol/fluticasone, metformin, lisinopril Social: Former smoker (30 pack-years), quit 5 years ago. Lives at home with wife. Vaccinations: Last flu shot 2 years ago; never received pneumococcal vaccine

Physical Examination

ParameterFinding
Temp39.8°C (103.6°F)
HR112 bpm
BP102/68 mmHg
RR26 breaths/min
SpO288% on room air
GCS14 (mildly confused)
Respiratory exam:
  • Decreased breath sounds right lower lobe
  • Dullness to percussion at right base
  • Bronchial breath sounds + coarse crackles right lower lobe
  • Egophony (E-to-A change) present at right base
Other: Dry mucous membranes, tachycardia, no JVD

Investigations

Labs:
  • WBC: 18,400/µL with 88% neutrophils, 10% bands (left shift)
  • CRP: 210 mg/L (elevated)
  • Procalcitonin: 3.8 ng/mL (elevated - suggests bacterial infection)
  • BUN/Cr: 32/1.6 (mildly elevated - dehydration)
  • Blood glucose: 290 mg/dL
  • Blood cultures: sent (×2 sets)
Chest X-Ray:
Chest X-ray showing right lower lobe lobar consolidation consistent with pneumonia
Right lower lobe lobar consolidation (dense opacity) with air bronchograms. No pneumothorax.

QUESTION: What is the Most Likely Diagnosis?


ANSWER: Community-Acquired Pneumonia (CAP) due to Streptococcus pneumoniae

Diagnostic Reasoning

This patient meets the criteria for Community-Acquired Pneumonia (CAP) - defined as an acute pulmonary infection in a patient who has not been hospitalized or residing in a long-term care facility for ≥14 days before presentation. (Tintinalli's Emergency Medicine)
The most likely causative organism is Streptococcus pneumoniae (pneumococcal pneumonia). Here is why:
Clinical CluePoints To
Sudden onset with shaking rigorsClassic pneumococcal feature
Rust-colored (blood-tinged) sputumPathognomonic for S. pneumoniae
Lobar consolidation on CXR (right lower lobe)Typical for pneumococcal CAP
Pleuritic chest painPleural involvement from pneumococcus
High fever (39.8°C) with marked leukocytosisTypical/bacterial rather than atypical
Age 68, COPD, DM, unvaccinatedClassic host risk factors
From Tintinalli's (the definitive EM reference): "Streptococcus pneumoniae - Sudden onset, fever, rigors, pleuritic chest pain, productive cough, dyspnea. Sputum: Rust-colored; gram-positive encapsulated diplococci. CXR: Lobar infiltrate, occasionally patchy, occasional pleural effusion."

Why NOT the Alternatives?

OrganismAgainst it in this case
Mycoplasma pneumoniae"Walking pneumonia" - gradual onset, dry cough, younger patients, interstitial pattern on CXR - not lobar
LegionellaNo diarrhea/GI symptoms, no water-exposure history, no hyponatremia; Legionella also shows multiple patchy non-segmented infiltrates, not lobar consolidation
KlebsiellaMore common in alcoholics; "currant jelly" sputum; upper lobe with bulging fissure sign
S. aureusGradual onset post-viral illness; multilobar patchy infiltrates, abscesses
H. influenzaeMore insidious; patient already has COPD but basilar patchy (not lobar) pattern
PE/CHFNo edema, no DVT risk factors, no bilateral involvement

Severity Assessment - PSI/PORT Score (CURB-65)

A rapid bedside tool used in the ED:
CURB-65 CriterionThis PatientPoints
Confusion (new)Yes (GCS 14)+1
Urea > 7 mmol/L (BUN > 20)Yes (BUN 32)+1
Respiratory rate ≥ 30/minYes (RR 26 - borderline)+1
Blood pressure (SBP <90 or DBP <60)Yes (BP 102/68)+1
65 years or olderYes (68 years)+1
CURB-65 Score = 4-5 → HIGH SEVERITY → Hospital admission (likely ICU)

Emergency Management

  1. Airway/Breathing: Supplemental O2 to maintain SpO2 ≥94%; prepare for possible NIV or intubation given SpO2 88%
  2. IV Access + Fluids: Aggressive fluid resuscitation for hypotension (30 mL/kg NS bolus)
  3. Antibiotics within 4 hours (ideally <1 hour for severe CAP):
    • IV Beta-lactam (ceftriaxone 1-2g IV) + macrolide (azithromycin 500mg IV) - for typical + atypical coverage
    • OR fluoroquinolone monotherapy (levofloxacin)
  4. Blood cultures × 2 before antibiotics (already sent)
  5. Urine Legionella/Pneumococcal antigens - especially for severe CAP
  6. Glucose control - address hyperglycemia (290 mg/dL)
  7. ICU consultation given CURB-65 ≥4 and hemodynamic instability
  8. Pneumococcal + influenza vaccination on discharge

Key Teaching Points

  • Rust-colored sputum + sudden onset + lobar consolidation = S. pneumoniae until proven otherwise
  • Always classify acquiring environment: CAP vs HAP vs VAP vs HCAP - this drives organism prediction and antibiotic choice
  • CURB-65 is the EM go-to severity score; PSI/PORT is more detailed
  • Atypical presentations (confusion only, no fever) are common in elderly and diabetic patients
  • Time-to-antibiotic matters - target <4 hours for CAP, <1 hour for septic patients

Sources: Tintinalli's Emergency Medicine: A Comprehensive Study Guide; Robbins & Kumar Basic Pathology; Goldman-Cecil Medicine; Murray & Nadel's Textbook of Respiratory Medicine
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