Severe pneumonia - When and why to hospitalize

Relatively simple objective criteria are now available to predict which pat ients are at risk for bad outcomes from community-acquired pneumonia. In ge neral, these include older patients and those with certain coexisting illne sses (especially neoplastic disease) or findings of altered mental status, hypotension, severe tachycardia, tachypnea, fever, acidemia, azotemia, hypo xemia, hyperglycemia, anemia, or hypnatremia. The major causes of severe pneumonia are S-pneumoniae, H-influenze, and L-p neumophila. Less common causes include mixed aerobic and anaerobic mouth fl ora, as well as M-pneumoniae, C-pneumoniae, Gram-negative bacilli, and S-au reus. Specific diagnosis is hampered by a lack of reliable diagnostic tests, but Gram's stain of expectorated sputum and cultures of sputum and blood may oc cassionally be helpful. Many emprical treatment regimens have been recommen ded, including those of the American Thoracic Society and the Infectious Di seases Society of America, which are reviewed here. It is hoped that better diagnostic tools will permit future targeting of mi crobes with narrow-spectrum therapy to diminish the risk of selection of re sistant strains with empirical regimens.