Impact of adequacy of initial antimicrobial therapy on the prognosis of patients with ventilator-associated pneumonia

To study the prognostic impact of the appropriateness of initial antimicrobial therapy in patients suffering from ventilator-associated pneumonia (VAP).

Observational cohort from January 1994 to December 2001 in one intensive care unit (ICU) from an university-affiliated, urban teaching hospital.

All 132 consecutive patients exhibiting bacteriologically documented VAP during ICU stay.

Initial antimicrobial treatment was deemed appropriate when the period from initial VAP diagnosis and subsequent administration of antibiotics was within 24 h and all causative pathogens were in vitro susceptible to at least one of the antibiotics of the regimen. Such a treatment was present in 106 episodes. Fifty-eight patients died. In bivariate analysis an appropriate initial antimicrobial therapy was associated with a significantly lower mortality rate (40% vs. 62%). In multivariate analysis the three independent factors present upon VAP onset and associated with death were pulmonary involvement of more than a single lobe on chest radiograph, platelet count less than 150,000/mm³, and Simplified Acute Physiology Score II higher than 37. Appropriate antimicrobial therapy was associated with a nonsignificant trend toward a lower mortality.

In our cohort the mortality rate was lower in patients suffering from VAP when the initial antimicrobial therapy was appropriate. However, such a factor did not appear as an independent prognostic factor.