SHM's Clinical Quick Talks-Community-Acquired Pneumonia

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Community-acquired pneumonia (CAP) is an infection of the lower respiratory tract in patients who are not at risk for healthcare-associated pneumonia. The most common bacteria causing CAP include Streptococcus pneumoniae, Mycoplasma, Haemophilus influenzae, Moraxella, Chlamydia, Legionella, and Staphylococcus aureus. Viral causes include influenza, rhinovirus, RSV, and parainfluenza. However, the etiology is often not identified due to low yield of cultures and therapy is empirical.<br /><br />Symptoms of CAP include dyspnea, fever, chills, cough, purulent sputum, and pleurisy. Elderly patients may present with nonspecific symptoms such as delirium or falls. Diagnosis is confirmed by the presence of a new or evolving infiltrate on chest x-ray. Laboratory tests may show leukocytosis, hyponatremia (in Legionella or Mycoplasma infections), and elevated LDH. Other tests, such as PCR for respiratory viruses and antigen tests for Legionella and Streptococcus pneumoniae, may also be performed.<br /><br />Treatment for CAP depends on the severity of illness. Outpatients are typically treated with macrolides or doxycycline. Inpatients may receive a combination of cephalosporins and doxycycline or azithromycin, or a respiratory fluoroquinolone. ICU patients may require combination therapy, including azithromycin or a respiratory fluoroquinolone along with antibiotics for MRSA and Pseudomonas coverage.<br /><br />Once patients are clinically stable, they can be transitioned from intravenous to oral antibiotics. The length of therapy is typically 5-7 days, with no advantage to prolonged therapy in uncomplicated CAP. Follow-up chest x-rays should be done to ensure the infection has cleared and to rule out underlying malignancy. Prevention includes administration of the pneumococcal vaccine to reduce future complications, and annual influenza vaccination.<br /><br />Cultures are often low yield and should not delay antibiotic treatment. If a patient does not respond to treatment, complications or alternate diagnoses should be considered. In conclusion, CAP is a common respiratory infection that requires prompt and appropriate treatment based on severity of illness.

Asset Subtitle

Ian Jenkins, Greg Seymann

Keywords

Community-acquired pneumonia

lower respiratory tract infection

Streptococcus pneumoniae

Mycoplasma

Haemophilus influenzae

Legionella

influenza

dyspnea

chest x-ray

antibiotics