420. Ventilator Associated Staphylococcus aureus and Pseudomonas aeruginosa Infections among ICU Patients in Six Healthcare Systems: Temporal Trends and Risk Factors
Session: Poster Abstract Session: HAI: Preventing Device-Associated Infections
Thursday, October 27, 2016
Room: Poster Hall

Ventilator-associated pneumonia (VAP) causes considerable morbidity and mortality among patients in in intensive care units (ICUs). While methicillin-resistant (MRSA) and susceptible (MSSA) S. aureus and Pseudomonas aeruginosa are prominent causes of these infections, their epidemiology is changing rapidly due to changes in clinical practice and patients susceptibility to infection. We estimated the incidence of VAP caused by S. aureus or P. Aeruginosa among patients in ICUs in 6 hospital systems over 2007-2012. We identified patient subgroups at elevated risk of infection.


Electronic administrative data and microbiological data were obtained for all patients that spent any time in a participating ICU. Our cohort included all patients in ICUs that were mechanically ventilated for > 48 hours. Exposure data included patient-level factors, including demographics, comorbidities, length of ICU stay, MRSA colonization status, preadmission origin, and procedure-level factors. The primary outcome was: VAP identified by an infection preventionist with laboratory confirmation of S. aureus or P. Aeruginosa.


Our dataset included 219,148 ICU stays, among which 39,456 included ventilator use for > 48 hours. Overall VAP rates varied year to year, but did not exhibit secular trends during this period. S. aureus caused 153 VAP episodes (40 [26%] MRSA and 113 [74%] MSSA) and P. aeruginosa caused 40. Patients < 30 had the highest VAP associated with SA rates over all time periods, adjusting for other covariates. Ventilated patients known to be colonized with S. aureus were 14.6 (95% CI 9.6, 22.2) times more likely to acquire MRSA VAP than patients that were not colonized. High incidence cohorts included patients admitted with trauma (OR 15.7 95% CI 3.98, 58.0) and those in the surgical intensive care units (OR 5.1 95% CI 1.2, 10.9).


VAP rates varied significantly by year and they did not decrease during the study period. The majority of VAP observed was attributed to MSSA, with much smaller percentages associated with MRSA and P. aeruginosa. Given the risk associated with MRSA carriage, ventilated patients may benefit from MRSA screening and interventions that target those who are colonized with SA.

Derek Cummings, PhD1, Rebecca Pierce, MS, BSN2, Keith S. Kaye, MD, MPH3, Connie Price, MD4, Loreen a. Herwaldt, MD, FIDSA, FSHEA5, Pranavi Sreeramoju, MD, MPH6, Rekha Murthy, MD, FIDSA, FSHEA7, Aaron M. Milstone, MD, MHS, FIDSA, FSHEA8, Eili Klein, PhD9, Lisa L. Maragakis, MD, MPH, FIDSA, FSHEA10, Mark Eickhoff, BS, MBA11, Frangiscos Sifakis, PhD, MPH11, Jenna Los, MLA12 and Trish M. Perl, MD, MSc, FIDSA, FSHEA13, (1)Biology, University of Florida, Gainesville, FL, (2)Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, (3)Detroit Medical Center and Wayne State University, Detroit, MI, (4)Infectious Diseases, University of Colorado School of Medicine/ Denver Health and Hospital, Denver, CO, (5)Internal Medicine, University of Iowa Carver College of Medicine, Iowa City, IA, (6)University of Texas Southwestern Medical Center, Dallas, TX, (7)Hospital Epidemiology, Cedars-Sinai Health System, Los Angeles, CA, (8)Pediatrics, The Johns Hopkins Medical Institutions, Baltimore, MD, (9)Emergency Medicine, Johns Hopkins University, Baltimore, MD, (10)The Johns Hopkins University School of Medicine, Baltimore, MD, (11)MedImmune, LLC, Gaithersburg, MD, (12)Medicine, Johns Hopkins University, Baltimore, MD, (13)Medicine, Johns Hopkins Medical Institutions, Baltimore, MD


D. Cummings, None

R. Pierce, None

K. S. Kaye, None

C. Price, None

L. A. Herwaldt, None

P. Sreeramoju, None

R. Murthy, None

A. M. Milstone, Sage Products LLC: Grant Investigator , Research grant
MITRE Corporation: Grant Investigator , Research grant

E. Klein, None

L. L. Maragakis, None

M. Eickhoff, MedImmune, LLC, member of AstraZeneca, LP group: Employee , Stock Grant

F. Sifakis, AstraZeneca, LP: Employee , Stock Grant

J. Los, MedImmune: Research Manager , Salary

T. M. Perl, MedImmune: Investigator , Salary
Pfizer: Scientific Advisor , honorarium

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