1141. Bacteremia in the setting of MRSA hospital-onset pneumonia is associated with a dramatic increase in the hospital length of stay: a retrospective cohort study
Session: Poster Abstract Session: MRSA/VRE Epidemiology
Friday, October 9, 2015
Room: Poster Hall
Background: Methicillin-resistant Staphylococcus aureus(MRSA) remains an important pathogen in pneumonia. Bacteremia may secondarily complicate MRSA pneumonia. Little is known about the epidemiology and outcomes of bacteremia complicating MRSA pneumonia.  Specifically the impact of concurrent bacteremia on hospital length of stay (LOS) in the setting of hospital-onset MRSA pneumonia (HOMP) is unclear.  We sought to describe the prevalence of bacteremia in HOMP and its impact on hospital LOS.

Methods: We conducted a single center retrospective cohort study (2008-2013) in adult patients with HOMP. We defined pneumonia based on clinical criteria and all cases were culture confirmed. MRSA bacteremia was identified based on blood cultures. Pneumonia was categorized as HOMP if it occurred >2 days after admission. We compared bacteremic and non-bacteremic groups with respect to demographic and clinical characteristics and outcomes. A generalized linear model (GLM) was constructed to examine the impact of bacteremia on post-pneumonia onset LOS. 

Results: Among the 513 patients with HOMP, 58 (11.3%) had concurrent bacteremia. Patients with bacteremia were similar to non-bacteremic subjects based on demographic and clinical characteristics with the exception of the prevalence of chronic liver disease (17.2% bacteremic vs. 8.6% non-bacteremic, p=0.034).  There was a trend towards more frequent recent hospitalization (prior 180 days) among bacteremic subjects (43.1% vs. 33.2%, p=0.134). The mean APACHE II scores at the onset of pneumonia did not differ between groups (16.2+/- 5.8 vs. 16.5+/- 5.7, p=0.506). The unadjusted mortality was numerically higher among those with bacteremia than those without (35.1% vs. 26.2%, p=0.220). Median post-pneumonia LOS (22.8 vs. 13.2 days, p<0.001) was greater in the bacteremic group. In a GLM controlling for multiple covariates including appropriateness of initial therapy, concomitant bacteremia was independently associated with a 13.5-day increase in the post-pneumonia hospital LOS (95% confidence interval 8.4 to 18.5 days). 

Conclusion: Concurrent bacteremia occurred with moderate frequency in the setting of MRSA HOMP. Bacteremia complicating MRSA HOMP added nearly two weeks to the hospital LOS.

Andrew F. Shorr, MD, MPH, Pulmonary and Critical Care Medicine, Washington Hospital Center, Washington, DC, Marya D. Zilberberg, MD, MPH, University of Massachusetts and Evimed Research Group, LLC, Goshen, MA, Scott Micek, PharmD, Pharmacy Practice, St. Louis College of Pharmacy, St. Louis, MO and Marin H. Kollef, MD, Pulmonary and Critical Care Medicine, Washington University School of Medicine, St. Louis, MO

Disclosures:

A. F. Shorr, Theravance: Consultant and Grant Investigator , Research grant
Cubist: Consultant and Investigator , Research grant
Pfizer: Consultant and Investigator , Research grant
Tetraphase: Consultant and Investigator , Research support
Medco: Consultant and Investigator , Research grant

M. D. Zilberberg, Theravance: Investigator , Research grant
Cubist: Consultant and Investigator , Research support
Tetraphase: Investigator , Research support
Medco: Investigator , Research grant

S. Micek, Theravance: Consultant and Investigator , Research support

M. H. Kollef, Theravance: Consultant and Investigator , Research grant

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