In October 2016, the Xpert® MRSA/SA BC assay, a PCR to detect MRSA from blood cultures, was implemented at Kelowna General Hospital. MRSA PCR was performed on one bottle per episode for blood cultures with gram positive cocci in clusters in at least 3/4 bottles. The medical microbiologist promptly phoned the most responsible physician with results to streamline antibiotics.
All episodes of MSSA bacteremia between January 1, 2013 to September 30, 2016 (pre-implementation group) and November 1, 2016 to January 31, 2018 (post-implementation group), were matched to corresponding vancomycin defined daily doses (DDD) and days of therapy (DOT) in pharmacy records. Patients with ≥5 DOTs were excluded if they had allergies to beta lactams, polymicrobial infections with organisms requiring vancomycin, were on hemodialysis (vancomycin convenience dosing), or were transferred from another hospital with known S. aureus bacteremia.
Mean vancomycin DDDs and DOTs, and the proportion of patients receiving at least one dose of vancomycin, were compared between groups. Categorical variables were analyzed using the chi-square test, while continuous variables were compared using the t-test.
In the pre-PCR group, 383 episodes of MSSA bacteremia were identified, with 21 excluded. In the post-PCR group, 100 episodes were found, with 3 excluded.
Significantly more patients received at least one dose of vancomycin in the pre-PCR (70.2%) compared to the post-PCR group (54.6%) (P<0.01). The mean DDD was 1.5 in the post-PCR group, less than the pre-PCR group at 2.8 (P<0.01). The mean DOT also decreased, with the post-PCR group receiving less vancomycin (1.6 days) compared to the pre-PCR group (2.5 days) (P<0.01).
Rapidly available MRSA PCR for S. aureus bloodstream infection coupled with antimicrobial stewardship performed by medical microbiologists led to a significant decrease in vancomycin use.
E. Blondel-Hill, None
B. Wang, None
A. Wilmer, None
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