Nosocomial pneumonia: the importance of a de-escalating strategy for antibiotic treatment of pneumonia in the ICU.

Nosocomial pneumonia is the second most frequent nosocomial infection and represents the leading cause of death from infections that are acquired in the hospital. In the last decade, a large body of data has accumulated that points to the substantial impact of inadequate antibiotic treatment as a major risk factor for infection-attributed mortality in ventilator-associated pneumonia (VAP) patients. In most instances, high-risk pathogens (eg, highly resistant Gram-negative bacilli, such as Pseudomonas aeruginosa and Acinetobacter spp, as well as methicillin-resistant staphylococci) are the predominant microorganisms causing excess mortality. Among various risk factors for mortality from VAP, which include the severity of the underlying disease and the degree of functional physiologic impairment caused by the pulmonary infectious process, only inappropriate antibiotic therapy is directly amenable to modification by clinicians. Secondary modifications of an initially failing antibiotic regimen do not substantially improve the outcome for these critically ill patients. Therefore, the best approach for reducing infection-related mortality seems to be the initial institution of an adequate and broad-spectrum antibiotic regimen in severely ill patients, which should be modified in a de-escalating strategy when the results from microbiologic testing become available. To circumvent the inherent danger of the emergence of resistance in ICU patients, additional measures have to be implemented and tested in clinical trials to reduce antibiotic consumption, shorten the duration of antibiotic treatment, and reduce the selection pressure on the ICU flora. This latter goal could be met by new antibiotic strategies including scheduled changes of recommended empiric antibiotic regimens at fixed intervals on a rotating basis.