to evaluate if a strategy based on routine endotracheal aspirate (ETA) cultures is better than using the ATS/IDSA guidelines to prescribe antimicrobials in ventilator associated pneumonia (VAP).
prospective observational cohort study
a 15-bed intensive care unit.
283 patients mechanically ventilated for ≥48h.
twice weekly ETA; bronchoalveolar lavage (BAL) culture if VAP was suspected.
146 different pairs of BAL (collected at the time of VAP)+ETA cultures (collected ≤ 7 days before VAP), were defined. We compared 2 models of 10 days of empiric antimicrobials (ETA-based vs ATS/IDSA guidelines-based strategies), analyzing their impact on appropriateness of therapy and total antimicrobial-days, using the BAL result as the standard for comparison.
complete ETA and BAL concordance (identical pathogens or negative result) happened in 52 pairs; discordance (false positive or false negative) in 67, and partial concordance in 2. ETA predicted the etiology in 62.4% of all pairs; in 74.0% of pairs if ETA was performed ≤2 days before BAL and in 46.2% if it was performed 3-7 days before BAL (p=0.016).Strategies based on the ATS/IDSA guidelines and on ETA results, led to appropriate therapy in 97.9% and 77.4% of pairs, respectively (p<0.001). The number of antimicrobial-days were 1942 and 1557, respectively (p<0.001).
the ATS/IDSA guidelines-based approach was more accurate than the ETA-based strategy, for prescribing appropriate initial empiric antibiotics in VAP, unless a sample is available ≤2 days of the onset of VAP. The ETA-based strategy led to fewer prescribed antimicrobial days.