777. Combination Vancomycin/Cefazolin (VAN/CFZ) for Methicillin-Resistant Staphylococcus aureus (MRSA) Bloodstream Infections (BSI)
Session: Poster Abstract Session: Treatment of Resistant Infections - Clinical Analyses
Thursday, October 5, 2017
Room: Poster Hall CD
Background: VAN remains the standard for MRSA BSI but has been associated with treatment failures and resulted in prolonged BSI durations and recurrences. In vitro studies of VAN/CFZ against MRSA demonstrated synergy and prevention of VAN resistance. However, clinical use of VAN/CFZ has not been reported. The objective of this study was to compare patient outcomes treated with VAN/CFZ vs. VAN for MRSA BSI.

Methods: This was a retrospective, cohort, comparative-effectiveness study of hospitalized adults ≥18y with ≥1 MRSA blood culture and received VAN/CFZ combination for ≥24h or VAN alone initiated within 72h of index infection between 1/1/08 and 5/1/17. Patients who received >24h beta-lactams other than CFZ, MRSA-active antibiotics other than VAN, with polymicrobial BSI, or had a second MRSA BSI episode during the study period were excluded. The primary composite failure outcome included: 30d mortality, MRSA BSI ≥7d, and 60d recurrence. Demographics were compared by Χ2, Fisher’s exact, Student’s t, or Mann-Whitney U tests. Multivariable regression models compared outcomes between the two treatment groups. Covariates with p-values ≤0.2 in bivariate analyses were included in the model.

Results: A total of 101 patients were included (CFZ/VAN = 41, VAN = 60). Demographics were similar except VAN patients were older (mean (±SD) age 58 (±14) v. 51 (±18) y, p=0.04), had higher median (IQR) Charlson Comorbidity Index (3 (2-5) v. 1 (0-4), p<0.01), APACHE II scores (13 (8-18) v. 11 (8-18), p=0.2), and more endocarditis BSI source (37% v. 20%, p = 0.06). After accounting for BSI source, VAN/CFZ (adjusted odds ratio [aOR], 95% confidence intervals [CI], 0.33, 0.13-0.83) and low APACHE II scores (aOR 1.07, 95% CI 1-1.15) were independently associated with fewer failures. Bivariate outcomes are in table below:

Variable, n (%)

VAN/CFZ

VAN

P value

Composite failure

10 (24)

31 (52)

0.006

30d mortality

3 (7.3)

5 (8.3)

1

BSI ≥7d

6 (15)

21 (35)

0.023

60d recurrence

3 (7.3)

9 (15)

0.351

Failure switch

1 (2.4)

10 (17)

0.026

Conclusion: In this cohort of MRSA BSI, patients treated with VAN/CFZ experienced fewer failures than with VAN alone, with shorter BSI durations. Additional studies are needed to confirm the role of VAN/CFZ combination treatment for MRSA BSI.

Trang D. Trinh, PharmD, MPH, BCPS, AAHIVP1, Evan J. Zasowski, PharmD, MPH, BCPS1, Abdalhamid M. Lagnf, MPH1, Sahil Bhatia, B.S.1, Sorabh Dhar, MD2, Ryan Mynatt, PharmD3, Jason M. Pogue, PharmD2 and Michael J. Rybak, PharmD, MPH, PhD1, (1)Anti-Infective Research Laboratory, Department of Pharmacy Practice, Wayne State University, Eugene Applebaum College of Pharmacy & Health Sciences, Detroit, MI, (2)Detroit Medical Center, Detroit, MI, (3)Detroit Medical Center / Wayne State University, Detroit, MI

Disclosures:

T. D. Trinh, None

E. J. Zasowski, None

A. M. Lagnf, None

S. Bhatia, None

S. Dhar, None

R. Mynatt, None

J. M. Pogue, Achaogen, Inc.: Consultant , Consulting fee

M. J. Rybak, Allergen: Scientific Advisor , Consulting fee

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