TABLE 32-3. -- Common Causes of Severe Community-Acquired Pneumonia* [†]

1. TABLE 32-1. -- Common Causes of Community-Acquired Pneumonia in Patients Who Do Not Require Hospitalization*MycoplasmapneumoniaeStreptococcus pneumoniaeChlamydophilapneumoniaeHaemophilusinfluenzaeRespiratory viruses

2. TABLE 32-3. -- Common Causes of Severe Community-Acquired Pneumonia*[†] Streptococcus pneumoniaeEnteric gram-negative bacilliStaphylococcus aureusLegionella spp.MycoplasmapneumoniaeRespiratory virusesPseudomonas aeruginosa (relative frequency determined by the presence or absence of specific risk factors)

3. 32-2. -- Common Causes of Community-Acquired Pneumonia in Patients Who Require Hospitalization*Streptococcus pneumoniaeMycoplasmapneumoniaeChlamydophilapneumoniaeHaemophilusinfluenzaeMixed infectionsEnteric gram-negative bacilliAspiration (anaerobes)Respiratory virusesLegionella spp.

4. PATIENTS WHO DO REQUIRE HOSPITALIZATION • Two sets of blood cultures• Gram stain and culture of a valid sputum sample• Urinary antigen test for detection of Legionellapneumophila (in endemic areas or during outbreaks)• Stain for acid-fast bacilli and culture of sputum (if tuberculosis is suggested by clinical history or radiologic findings)• Fungal stain and culture of sputum, and fungal serologies (if infection by an endemic mycosis is suggested by the clinical history or radiologic findings)• Sputum examination for Pneumocystisjirovecii (if suggested by clinical history or radiologic findings)• Serologies for Mycoplasmapneumoniae, Chlamydophilapneumoniae, Chlamydophilapsittaci, Coxiellaburnetii, Legionella spp., and respiratory viruses (in endemic areas or during outbreaks)• Culture and microscopic evaluatio