Background: The 2005 guidelines of the American Thoracic Society-Infectious Diseases Society of America Guidelines for Hospital for managing hospital-acquired pneumonia classified patients according to time of onset and risk factors for potentially drug-resistant microorganisms to select the empirical antimicrobial treatment. We assessed the microbial prediction and validated the adequacy of these guidelines for antibiotic strategy.
Methods: We prospectively observed 276 patients with intensive care unit-acquired pneumonia. We classified patients into group 1 (early onset without risk factors for potentially drug-resistant microorganisms; 38 patients) and group 2 (late onset or risk factors for potentially drug-resistant microorganisms; 238 patients). We determined the accuracy of guidelines to predict causative microorganisms and the influence of guidelines adherence in patients' outcome.
Results: Microbial prediction was lower in group 1 than in group 2 (12 [50%] of 24 vs 119 [92%] of 129; P < .001) mainly because of potentially drug-resistant microorganisms in 10 patients (26%) from group 1. Guideline adherence was higher in group 2 (153 [64%] vs 7 [18%]; P < .001). Guideline adherence resulted in more treatment adequacy than did nonadherence (69 [83%] vs 45 [64%]; P = .013) and a trend toward better response to empirical treatment in group 2 only but did not influence mortality. Reclassifying patients according to the risk factors for potentially drug-resistant microorganisms of the former 1996 American Thoracic Society guidelines increased microbial prediction in group 1 to 21 (88%; P = .014); all except 1 patient with potentially drug-resistant microorganisms were correctly identified by these guidelines.
Conclusions: The 2005 guidelines predict potentially drug-resistant microorganisms worse than the 1996 guidelines. Adherence to guidelines resulted in more adequate treatment and a trend to a better clinical response in group 2, but it did not influence mortality.