Are quantitative cultures useful in the diagnosis of hospital-acquired pneumonia?

Noninvasive and invasive tests have been developed and studied for their utility in diagnosing and guiding the treatment of hospital-acquired pneumonia, a condition with an inherently high mortality. Early empiric antibiotic treatment has been shown to reduce mortality, so delaying this treatment until test results are available is not justifiable. Furthermore, tailoring therapy based on results of either noninvasive or invasive tests has not been clearly shown to affect morbidity and mortality. This may be related to quantitative limitations of these tests or possibly to a high false-negative rate in patients who receive early antibiotic treatment and may therefore have suppressed bacterial counts. Results of these tests, however, do influence treatment. It is therefore hoped that they may ultimately provide a rational basis for making therapeutic decisions. In the future, outcomes research should be a part of large-scale clinical trials, and noninvasive and invasive tests should be incorporated into the design in an attempt to provide a better understanding of the value of such tests.