In an issue of CHEST (July 2013), Luna et al1Luna CM Sarquis S Niederman MS et al.Is a strategy based on routine endotracheal cultures the best way to prescribe antibiotics in ventilator-associated pneumonia?.Chest. 2013; 144: 63-71Abstract Full Text Full Text PDF PubMed Scopus (38) Google Scholar presented a well-designed study to help elucidate the controversy on routine surveillance respiratory cultures to guide antibiotic treatment of ventilator-associated pneumonia (VAP) compared with the current practice of empirical, broad-spectrum antibiotic therapy with deescalation based on American Thoracic Society/Infectious Diseases Society of America guidelines. We commend the authors on their effort in using a prospective randomized protocol hybridized with a generated theoretical outcome for their intervention arm, such that no patients were harmed in this study. However, their findings did raise a question we cannot answer: Why were there fewer days of antimicrobial exposure in the surveillance endotracheal aspirate (ETA) group relative to the guideline-treated group? It was unclear from the article if the length of duration was shorter in the ETA group due to death foreshortening the planned time frame or if a short duration was intentional, thus, leading to death from inadequate dosing, which is a possible confounding factor of the difference in outcomes between the two groups. Their hypothesized protocol involved holding off on the initiation of antibiotics with a negative ETA. A delay in antibiotic administration is known to be associated with mortality, so empirical antibiotics in suspected VAP are recommended prior to any culture results.2Guidelines for the management of adults with hospital-acquired, ventilator-associated, and healthcare-associated pneumonia.Am J Respir Crit Care Med. 2005; 171 (American Thoracic Society; Infectious Diseases Society of America): 388-416Crossref PubMed Scopus (5319) Google Scholar With the risk of mortality outweighing the benefit of expediting deescalation of antimicrobials, most physicians will not change this practice. Those treated based on guidelines would be expected to have a shorter duration as the days on empirical therapy could be factored into the overall planned duration, while the ETA group will need a longer antibiotic duration with drug escalation. The authors also did not state clearly if the guideline-treated group had stopped treatment with antimicrobials within 48 to 72 h based on negative BAL or if the duration often deviated from the 7-to 8-day minimum or 10-day Pseudomonas recommended treatment to longer regimens based on clinician preference. In an era of increasing antimicrobial resistance, the need for antibiotic stewardship is important, and we applaud the authors in investigating a modality that could potentially shorten antimicrobial duration. However, due to the risk of excessive mortality and morbidity of VAP, our conclusion is that we will not change our clinical practice from the current recommended guidelines.

SESSION TITLE: ICU Infections Posters

Introduction: There exist few data about the eradication rate of endotracheal colonization during the therapy for VAP. Aims: We evaluated eradication by ETA cultures in a cohort of patients with microbiologically confirmed VAP. Methods: VAP was diagnosed in those mechanically ventilated patients for ≥ 48 h who developed clinical criteria plus a BAL culture grew ≥ 10 4 colony forming units (cfu) of any pathogenic microorganism. Colonization was studied by bi-weekly endotracheal aspirate (ETA) quantitative cultures. Results: 68 episodes of VAP had performed at least one follow-up ETA culture. The VAP pathogens and those newly acquired during the therapy are displayed in table 1. The rate of eradication and the rate of newly acquired colonization is displayed in figure 1. Pathogens persisted during 6.7 days for P. aeruginosa , 6.5 days Acinetobacter spp, 2.4 days S. aureus and 4.0 days other pathogens. Conclusions: Endotracheal colonization persisted despite appropriate therapy; acquired colonization appeared after the second follow up culture and could precede a recurrent VAP episode.

ObjectivesThe objectives of this study were to evaluate if a strategy based on routine endotracheal aspirate (ETA) cultures is better than using the American Thoracic Society/Infectious Diseases Society of America (ATS/IDSA) guidelines to prescribe antimicrobials in ventilator-associated pneumonia (VAP).MethodsThis was a prospective, observational, cohort study conducted in a 15-bed ICU and comprising 283 patients who were mechanically ventilated for ≥ 48 h. Interventions included twice-weekly ETA; BAL culture was done if VAP was suspected. BAL (collected at the time of VAP) plus ETA cultures (collected ≤ 7 days before VAP) (n = 146 different pairs) were defined. We compared two models of 10 days of empirical 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.ResultsComplete ETA and BAL culture concordance (identical pathogens or negative result) occurred in 52 pairs; discordance (false positive or false negative) in 67, and partial concordance in two. 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% of pairs if ETA was performed 3 to 7 days before BAL (P = .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 < .001). The numbers of antimicrobial-days were 1,942 and 1,557 for therapies based on ATS/IDSA guidelines and ETA results, respectively (P < .001).ConclusionsThe ATS/IDSA guidelines-based approach was more accurate than the ETA-based strategy for prescribing appropriate, initial, empirical antibiotics in VAP, unless a sample was available ≤ 2 days of the onset of VAP. The ETA-based strategy led to fewer days on prescribed antimicrobials.