Prophylactic strategies for hospitalized patients at risk for pneumonia.

Thirty-five years ago pneumonia prophylaxis failed because the agents available then did not have the antibacterial spectrum necessary to prevent colonization and infection with multiple gram-negative bacteria. Combinations of the newer antibiotics delivered intratracheally do cover most common organisms and they may be sufficient for prophylaxis. Careful monitoring is necessary because a number of unusual pathogens have the potential to circumvent the prophylactic regimen. Widespread use of topical antibiotics may result in the emergence of antimicrobial resistance in intensive care unit areas. The magnitude of this risk is difficult to calculate and some maneuvers are available to decrease the likelihood that this will occur. Nevertheless, at present these uncertainties are sufficient to prevent the routine clinical use of antibiotics for pneumonia prophylaxis. There are now eight studies showing that prophylaxis can decrease the incidence of pneumonia by greater than 50%. These should stimulate further clinical research designed to minimize the problems with bacterial resistance.