Table 2.
Clues to the cause of pneumonia from history and physical examination
| Factor | Possible Agent(s) |
|---|---|
| Host factor | |
| Sickle cell disease | Streptococcus pneumoniae |
| Human immunodeficiency virus infection and CD4+ lymphocyte count of <200/μL | Streptococcus pneumoniae, Haemophilus influenzae, Cryptococcus neoformans, Mycobacterium tuberculosis |
| Structural lung disease (bronchiectasis) | Pseudomonas aeruginosa |
| Travel | |
| Travel to southeast Asia | Burkholderia pseudomallei, Mycobacterium tuberculosis |
| Travel to China, Taiwan, Toronto, Canada, Middle East | Coronavirus causing SARS |
| Travel to tuberculosis-endemic countries | Mycobacterium tuberculosis |
| Travel to desert regions of southwestern United States, and Central and South America | Coccidioides immitis |
| Travel to Ohio and St Lawrence River valleys | Histoplasma capsulatum |
| Travel to Peru | Sporothrix schenckii |
| Travel to Vancouver Island, Canada, and Pacific Northwest (camping, residence) | Cryptococcus gattii |
| Other environmental factors | |
| Pneumonia outbreak in a homeless shelter | Streptococcus pneumoniae, Mycobacterium tuberculosis |
| Lawn mowing in an endemic area, including southcentral and western states and Martha’s Vineyard | Francisella tularensis |
| Exposure to parturient cats, sheep, goats, and cattle in an endemic area, including western and plains states where ranching and rearing of cattle are common | Coxiella burnetii |
| Sleeping in a rose garden, playing on bales of hay | Sporothrix schenckii |
| Exposure to windstorm in an endemic area | Coccidioides immitis, Coxiella burnetii |
| Exposure to bats, excavation or residence in an endemic area | Histoplasma capsulatum |
| Camping, cutting down trees in an endemic area, including the Mississippi River and Ohio River valley basins and around the Great Lakes | Blastomyces dermatitidis |
| Exposure to mouse droppings in an endemic area, including the Four Corners and Yosemite National Park | Hantavirus |
| Immunosuppressed and exposure to hot tub; grocery store mist machine; recent stay in a hotel; visit to or recent stay in a hospital with Legionellaceae-contaminated drinking water | Legionella pneumophila, other Legionellaceae |