Background: Evaluation of causative pathogens is vital for optimizing empiric antibiotic
therapy of ventilator-associated pneumonia (VAP). Based on previous data (Ann Surg
1998;227:743–755), empiric antibiotics for our VAP clinical pathway were modified to target
early and late occurring pathogens (ampicillin/sulbactam during the first week of hospitalization;
cefepime plus vancomycin afterwards). The objectives of this study were to compare
organisms causing VAP over a three-year period to previous data, and to determine the adequacy
of the empiric antibiotic regimens.
Methods: A total of 299 critically ill trauma patients with VAP over a three-year period were
studied retrospectively. The incidence of pathogens causing VAP in the study period were
compared to a previously published study of a two-year period in our intensive care unit
(ICU). Sensitivities of Pseudomonas aeruginosa and Acinetobacter baumannii were evaluated
over the study period. The adequacy of empiric antibiotic therapy for each episode of VAP
was determined. Therapy was considered to be adequate if one or more antibiotics had in
vitro activity against the organism causing VAP.
Results: Statistically significant changes in pathogens included increased Staphylococcus aureus (incidence 17% vs. 11%, p = 0.024) and decreased Acinetobacter baumannii (11% vs.
22%, p < 0.001). Susceptibility patterns were statistically unchanged except for increased resistance
of P. aeruginosa to extended-spectrum penicillins (p = 0.016). Empiric therapy was
adequate in 76% of VAP episodes.
Conclusions: The clinical pathway's empiric antibiotic regimen was associated with only
modest changes in organisms causing VAP and provided a high rate of adequate empiric coverage.
