Early and late treatment failure in community-acquired pneumonia.

Treatment failure is a matter of great concern in the management of community-acquired pneumonia (CAP). Defined generally as lack of response or clinical deterioration, failure is considered early when it occurs within the first 72 hours and late when it occurs after 72 hours. The reported incidence of treatment failure among hospitalized patients with CAP ranges from 2.4 to 31% for early failure and from 3.9 to 11% for late failure. Most cases of early failure occur because of inadequate host-pathogen responses. Factors associated with treatment failure include high-risk pneumonia, liver disease, multilobar infiltrates, Legionella pneumonia, gram-negative pneumonia, pleural effusion, cavitation, leucopenia, and discordant antimicrobial therapy. Conversely, influenza vaccination, initial treatment with fluoroquinolones, and chronic obstructive pulmonary disease have been linked with a lower risk of failure. Treatment failure is associated with high morbidity and mortality rates. Its detection and management require careful clinical assessment. Certain serum biological markers may be helpful to identify patients with a higher risk of deterioration and poor prognosis. Because inadequate host-pathogen responses are responsible for a significant number of failures, strategies aimed at modulating the inflammatory response should be investigated. Discordant therapy can be prevented by rational application of the current antibiotic guidelines.