This article is written live from ID Week 2017 Annual Meeting in San Diego, CA. MPR will be reporting news on the latest findings from leading experts in infectious diseases. Check back for more news from IDWeek 2017.

SAN DIEGO—Patients with methicillin-resistant Staphylococcus aureus (MRSA) bloodstream infections (BSI) had fewer failures with vancomycin/cefazolin (VAN/CFZ) combination therapy vs. vancomycin (VAN) alone, reported Trang D. Trinh, PharmD, from Wayne State University, Detroit, MI, and coauthors.

“In our cohort of MRSA BSI, patients treated with VAN/CFZ experienced fewer composite failures when compared to VAN monotherapy,” Dr. Trinh and colleagues reported. “VAN/CFZ is a promising combination to consider for treatment of MRSA BSI.” 

Although the standard treatment for MRSA BSI, vancomycin has been tied to treatment failures leading to longer BSI duration and recurrences. Vancomycin in combination with cefazolin has shown synergistic effects in in vitro studies while preventing vancomycin resistance. Dr. Trinh and colleagues, therefore, compared patient outcomes among those treated with VAN/CFZ vs. VAN alone for MRSA BSI by conducting a retrospective, cohort, comparative-effectiveness study. 

Hospitalized patients aged ≥18 years with at least 1 MRSA blood culture who received VAN/CFZ (n=41) for ≥24 hours or VAN alone (n=60) initiated within 72 hours of index infection were included. “Patients who received >24 hours 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,” stated Dr. Trinh. 

The primary composite failure outcome included 30-day mortality, MRSA BSI lasting at least 7 days, and 60-day recurrence. 

VAN/CFZ treatment (adjusted odds ratio [aOR] 0.33, 95% CI: 0.13–0.83; P=0.02) and low APACHE II scores (aOR 1.07, 95% CI: 1–1.15; P=0.05) were independently associated with fewer treatment failures, after having accounted for the source of BSI. 

Composite failure was lower in the VAN/CFZ group vs. VAN alone (24% vs. 52%). 30-day mortality rates (7.3% vs. 8.3%) and 60-day recurrence rates (7.3% vs. 15%) were lower in the VAN/CFZ group vs. VAN alone, but the differences reached statistical significance only for composite failure (P=0.006). There were also fewer BSI duration ≥7 days among the VAN/CFZ group vs. VAN alone (15% vs. 35% ; P=0.023). 

Shorter BSI durations and fewer treatment failures were seen with VAN/CFZ among this group of patients with MRSA BSI, the authors concluded. More studies are needed to determine the role of VAN/CFZ combination therapy for MRSA BSI. 

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Trinh, Trang D. PharmD. Combination Vancomycin/Cefazolin (VAN/CFZ) for Methicillin-Resistant Staphylococcus aureus (MRSA) Bloodstream Infections (BSI). Poster presented at IDWeek; October 4–8, 2017; San Diego, CA.