Community-Acquired Pneumonia
A 30-year-old previously healthy man has three days of fever, productive cough and pleuritic pain. Temperature is 39.1 °C, respiratory rate 26 breaths/min, blood pressure 118/70 mm Hg, oxygen saturation 91% on room air, and white cell count 18 × 10⁹/L. Chest radiography shows right middle lobe consolidation. He is admitted to a general ward. Which antibiotic regimen is most appropriate?
- A.Ciprofloxacin plus gentamicin
- B.Piperacillin-tazobactam plus vancomycin
- C.Meropenem plus amikacin
- D.Cefotaxime plus azithromycinCorrect
Explanation
This is community-acquired pneumonia in a previously healthy young adult with no recent hospitalization, no intravenous antibiotics in the past 90 days and no structural lung disease, so the likely pathogens are Streptococcus pneumoniae, Haemophilus influenzae, Mycoplasma pneumoniae, Chlamydophila pneumoniae and respiratory viruses. Standard empirical therapy for a non-severe ward admission is a beta-lactam such as ceftriaxone, cefotaxime or ampicillin-sulbactam combined with a macrolide, or alternatively a respiratory fluoroquinolone such as levofloxacin or moxifloxacin as monotherapy. The macrolide covers atypical organisms that the beta-lactam misses, and combination therapy is associated with better outcomes than beta-lactam alone in hospitalized patients. Antipseudomonal and anti-MRSA agents such as piperacillin-tazobactam with vancomycin should be reserved for patients with documented prior colonization or risk factors for resistant organisms, because unnecessary broad coverage selects for resistance and causes avoidable toxicity and Clostridioides difficile infection. Carbapenems with aminoglycosides are hospital-acquired or ventilator-associated pneumonia regimens and are inappropriate here. Ciprofloxacin has poor pneumococcal activity and is not a respiratory fluoroquinolone, and adding gentamicin adds nephrotoxicity without covering the likely pathogens. Severity assessment with CURB-65 or the pneumonia severity index guides site of care, and this patient's hypoxemia and tachypnea justify admission. Antibiotics should be started promptly and de-escalated once cultures and clinical response allow, usually for a minimum five-day course.
Why each option
- A.
- Ciprofloxacin has weak pneumococcal activity and gentamicin does not cover the likely respiratory pathogens.
- B.
- Antipseudomonal and anti-MRSA cover is unnecessary without risk factors and promotes resistance and toxicity.
- C.
- A carbapenem plus aminoglycoside is a hospital-acquired pneumonia regimen and is far too broad for this presentation.
- D.
- Correct. A third-generation cephalosporin plus a macrolide covers typical and atypical pathogens and is standard for ward-admitted community-acquired pneumonia.
Reference: ATS/IDSA Guideline on the Diagnosis and Treatment of Adults with Community-acquired Pneumonia, 2019
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