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Difficulty: MediumInfectious Diseases

A 68-year-old man is brought to the emergency department by his son because he has been acting confused since yesterday morning. For the past three days, he has also experienced subjective fevers, chills, and a cough productive of yellowish sputum. His medical history includes hypertension, benign prostatic hyperplasia, and osteoarthritis. He does not use tobacco, alcohol, or illicit substances. His temperature is 38.7∘C38.7^\circ\text{C} (101.7∘F101.7^\circ\text{F}), pulse is 102/min102/\text{min}, blood pressure is 115/70 mmHg115/70\text{ mmHg}, and respiratory rate is 24/min24/\text{min}. Pulse oximetry indicates an oxygen saturation of 92%92\% on room air. He appears acutely ill and is oriented only to person. Pulmonary auscultation reveals crackles and bronchial breath sounds over the left lower lung fields. Laboratory evaluation is notable for a leukocyte count of 15,500/mm315,500/\text{mm}^3 and a blood urea nitrogen (BUN) level of 24 mg/dL24\text{ mg/dL}. Chest radiography demonstrates a dense left lower lobe consolidation. The patient is admitted to the general medical ward. Which of the following is the most appropriate empiric pharmacotherapy for this patient?

  1. Intravenous ceftriaxone and azithromycinAnswer
  2. B
    Oral amoxicillin-clavulanate and azithromycin
  3. C
    Intravenous piperacillin-tazobactam and vancomycin
  4. D
    Intravenous ciprofloxacin
  5. E
    Oral amoxicillin

Answer

Intravenous ceftriaxone and azithromycin
The correct answer is intravenous ceftriaxone and azithromycin. This patient presents with community-acquired pneumonia (CAP) and signs of significant severity, including confusion and an elevated blood urea nitrogen (BUN). Utilizing the CURB-65 scoring system, he scores 3 points (Confusion, BUN > 19 mg/dL, Age > 65), which mandates inpatient admission to a medical ward. Current guidelines recommend that non-ICU inpatients with CAP be treated empirically with a beta-lactam (such as intravenous ceftriaxone, cefotaxime, or ampicillin-sulbactam) combined with a macrolide (such as azithromycin). Alternatively, monotherapy with a respiratory fluoroquinolone (like levofloxacin or moxifloxacin) can be used. This beta-lactam plus macrolide combination effectively targets the most common typical organisms (e.g., Streptococcus pneumoniae, Haemophilus influenzae) as well as atypical organisms (e.g., Mycoplasma pneumoniae, Legionella pneumophila).

Step-by-Step Solution

1
Calculate the patient's severity using a validated scoring system such as CURB-65.
The patient scores 3 points (Confusion = 1, BUN > 19 mg/dL = 1, Age > 65 = 1).
Determines the appropriate site of care (outpatient vs. inpatient ward vs. ICU).
2
Determine the appropriate setting for treatment based on the severity score.
A CURB-65 score of 3 indicates severe community-acquired pneumonia warranting inpatient hospital admission.
Patients with scores 0-1 can typically be treated as outpatients, a score of 2 requires consideration for admission, and 3-5 require hospital admission.
3
Select the guideline-concordant empiric antibiotic regimen for inpatient (non-ICU) community-acquired pneumonia.
The standard of care is an intravenous beta-lactam (e.g., ceftriaxone) plus a macrolide (e.g., azithromycin), or monotherapy with a respiratory fluoroquinolone.
This regimen covers the most common typical and atypical respiratory pathogens without unnecessarily broadening the spectrum.

Key Concept

Empiric antibiotic selection for inpatient community-acquired pneumonia
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Topics

Infectious Diseases

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