Definition

  • Lower respiratory tract infection in a nonhospitalized person that is associated with symptoms of acute infection with or without new infiltrate on chest radiographs

Clinical presentation

  • Temperature greater than 38°C (100.4°F)

  • Cough with or without sputum, hemoptysis

  • Pleuritic chest pain

  • Myalgia

  • Gastrointestinal symptoms

  • Dyspnea

  • Malaise, fatigue

  • Rales, rhonchi, wheezing

  • Egophony, bronchial breath sounds

  • Dullness to percussion

  • Atypical symptoms in older patients

Etiology

  • Bacterial

    Chlamydia species

    Haemophilus influenzae

    Legionella species

    Moraxella catarrhalis

    Mycoplasma pneumoniae

    Staphylococcus aureus

    Streptococcus pneumoniae

  • Viral

    Adenovirus

    Influenza A and B

    Parainfluenza

    Respiratorysyncytial virus

  • Endemic fungi

    Blastomycosis

    Coccidioidomycosis

    Histoplasmosis

Risk factors

  • Age older than 65 years

  • Human immunodeficiency virus or immunocompromised

  • Recent antibiotic therapy or resistance to antibiotics

  • Comorbidities

    Asthma

    Cerebrovascular disease

    Chronic obstructive pulmonary disease

    Chronic renal failure

    Congestive heart failure

    Diabetes

    Liver disease

    Neoplastic disease