384. Efficacy of Vancomycin Therapy for the Treatment of Methicillin-Resistant Staphylococcus aureus (MRSA) Ventilator-Associated Pneumonia (VAP) with Vancomycin MICs </= 0.5 vs. Vancomycin MICs >/= 1
Session: Poster Session: Hospital-acquired and Transplant Infections
Friday, October 30, 2009: 12:00 AM
Room: Poster Hall A
Background: Increasing vancomycin MICs and the emergence of vancomycin resistance among MRSA isolates have been associated with decreased clinical response rates. Objectives were to: compare clinical response rates in MRSA VAP with vancomycin MICs </= 0.5 vs. MICs >/= 1; compare clinical response rates in MRSA VAP with vancomycin MICs </= 1 vs. MIC = 2; describe vancomycin trough levels in patients (pts) who experienced clinical response vs. clinical failure at the end of vancomycin therapy (EOT); compare clinical response rates in MRSA VAP with trough levels >/= 15 mcg/mL vs. trough levels < 15 mcg/mL.
Methods: IRB approval was obtained for this retrospective cohort study conducted from 1/1/04-12/31/08. Inclusion criteria: VAP diagnosis per CDC criteria, positive MRSA on respiratory culture, received IV vancomycin for >/= 72 hours. Exclusion criteria: age < 18 years (yrs), age > 89 yrs, pregnancy.
Results: Of 342 pts diagnosed with VAP, 53 pts met full study criteria. For MICs </= 0.5 (n=16) vs. MICs >/= 1 (n=37) respectively, mean age was 54.7 +/- 17.4 yrs vs. 61.7 +/- 15.1 (p=0.14); male sex was 43.8% vs. 64.9% (p=0.26); mean APACHE II score was 13.6 +/- 4.3 vs. 12.7 +/- 4.0 (p=0.5); clinical response at EOT was 81.3% vs. 78.4% (p=1.0). When comparing MICs </= 1 vs. MIC = 2, 18/23 pts (78.3%) experienced clinical response at EOT vs. 24/30 pts (80%) (p=1.0). For MICs </= 0.5, the mean trough level was 11.9 +/- 4 mcg/mL in pts who experienced clinical response at EOT vs. 18.0 +/- 16.6 mcg/mL in pts with clinical failure (p=0.2). For MICs >/= 1, the mean trough level was 14.2 +/- 6 mcg/mL in pts with clinical response at EOT vs. 13.9 +/- 11 mcg/mL in pts with clinical failure (p=0.92). Clinical response at EOT was 9/13 pts (69.2%) with mean trough levels >/= 15 mcg/mL vs. 32/38 pts (84.2%) with mean trough levels < 15 mcg/mL (p=0.25).
Conclusions: Similar clinical response rates were seen regardless of the patient’s MIC value or trough levels and when comparing trough levels >/= 15 mcg/mL vs. < 15 mcg/mL. Further study is warranted in a larger patient population.
Nitin Bhanot, MD, MPH1, Noreen Chan-Tompkins, PharmD1, Jenna Ferrara, PharmD1, Cheryl Herbert, RN, CIC1, Andrew Sahud, MD1 and  J. Ferrara, None..
N. H. Chan-Tompkins, None..
N. Bhanot, None..
C. Herbert, None..
A. Sahud, None., (1)Allegheny General Hospital, Pittsburgh, PA