Is a Strategy Based on Routine Endotracheal Cultures the Best Way to Prescribe Antibiotics in Ventilator-Associated Pneumonia? CHEST 2013; 144(1):63-71 Carlos M. Luna, MD, PhD, FCCP; Sergio Sarquis, MD; Michael S. Niederman, MD; Fernando A. Sosa, MD; Maria Otaola, MD; Nicolas Bailleau, MD; Carlos A. Vay, PhD; Angela Famiglietti, PhD; Celica Irrazabal, MD; and Abelardo A. Capdevila, MD 호흡기내과 2 년차 박세정

Ventilator-associated pneumonia (VAP) - Mechanical ventilation ≥48 h - Most frequent ICU-acquired infection among pts receiving mechanical ventilation. - Most frequent cause of death among nosocomial infections % of patients with ventilator - mortality rate 20-75% * inappropriate therapy (no coverage for the pathogen) * overuse * prolonged exposure beyond what is necessary Hypothesis: Routine endotracheal aspirates (ETAs) in pts receiving ventilation are an accurate way to select appropriate antimicrobial therapy covering most of the involved pathogens adapted to the local epidemiology, compared with the use of empirical therapy suggested by the ATS/IDSA guidelines.

MATERIALS AND METHODS Study Design and Subjects ICU of a teaching hospital in Buenos Aires, Argentina October 2005 ~ September 2007 ≥ 18 years old Ventilation ≥ 48 h Exclusion criteria : AIDS-defining conditions or neutropenia(<500/mm 3 ) at admission : lab, CXR, volume & quality of secretions, ABGA  to evaluated the potential presence of VAP * routine, biweekly tracheal aspirate cultures * daily evaluation for the presence of VAP * record of antimicrobial therapy * clinical diagnosis of VAP  BAL culture (within 6h) * f/u until hospital discharge or death. Procedures ETA cultures collected every Monday and Thursday (8:00 ~ 9:00 AM) (positive culture of the first ETA = basal colonization)

MATERIALS AND METHODS Clinical Diagnosis of VAP * intubated *ventilated *new or progressive CXR infiltrate + 2 of: (1) BT > 38°C or 12,000 or <4,000 per mL, (3) macroscopically purulent tracheal aspirate microbiologic confirm : ≥ 10 4 CFU/mL on BAL culture, followed by the prescription of antimicrobials for pneumonia Appropriate Antibiotic Therapy = coverage of all the pathogens isolated in the BAL at least one of the antimicrobials administered at the onset of VAP for Pseudomonas aeruginosa: 5 days of combination therapy (2 antipseudomonal (β-lactam + non-β-lactam), susceptibility to at least 1)

MATERIALS AND METHODS Theoretical Models of Antimicrobial Use: Antimicrobial-Days appropriate use inappropriate use overuse

RESULTS Patient Characteristics

RESULTS Value of ETA Cultures for Predicting VAP Etiology

RESULTS Appropriateness of Antibiotic Therapy According to Different Strategies

DISCUSSION Does not support the hypothesis that routine ETA performed twice a week would be a better way to prescribe antimicrobials in suspected VAP, compared with the use of an empirical therapy based on the ATS/IDSA guidelines. ATS/IDSA guideline 2005 vs earlier guidelines: (1) patients at risk for MDR pathogens should receive MRSA + dual GN coverage to increase the likelihood of initially appropriate therapy (2) when culture data became available, de-escalation to fewer drugs with a narrower spectrum of coverage should occur (3) long durations of combination GN therapy could increase toxicity, antibiotic resistance, and mortality. Limitations : - performed at only one institution - the use of only basic, standard measures of prevention + older age  could lead to a higher colonization rate

CONCLUSION ATS/IDSA guidelines based strategy was preferable to ETA-based strategy for antibiotic selection in patients with a first episode of VAP, rather than a recurrent episode. ATS/IDSA guidelines led to a significantly higher rate of early and appropriate therapy, although at the cost of more antimicrobial-days.