Comparative effectiveness of β-lactam versus vancomycin empiric therapy in patients with methicillin-susceptible Staphylococcus aureus (MSSA) bacteremia.
BACKGROUND
Vancomycin may be inferior to β-lactams for the empiric treatment of methicillin-susceptible Staphylococcus aureus (MSSA) bacteremia. We compared empiric β-lactams to vancomycin to assess clinical outcomes in patients with MSSA bacteremia.


METHODS
We conducted a retrospective cohort study of adult inpatients with their first episode of MSSA bacteremia at two tertiary care hospitals in Vancouver, Canada, between 2007 and 2014. Exposure was either empiric β-lactam with or without vancomycin or vancomycin monotherapy. All patients received definitive treatment with cloxacillin or cefazolin. The primary outcome was 28-day mortality. Secondary outcomes were 90-day mortality, duration of bacteremia, and hospital length-of-stay. Outcomes were adjusted using multivariable logistic regression.


RESULTS
Of 669 patients identified, 255 met inclusion criteria (β-lactam = 131, vancomycin = 124). Overall 28-day mortality was 7.06 % (n = 18). There were more cases of infective endocarditis in the β-lactam than in the vancomycin group [24 (18.3 %) vs 12 (9.7 %), p = 0.05]. Adjusted mortality at 28 days was similar between the two groups (OR 0.85; 95 % CI 0.27-2.67). The duration of bacteremia was longer in the vancomycin group (97.1 vs 70.7 h, p = 0.007). Transition to cloxacillin or cefazolin occurred within a median of 68.3 h in the vancomycin group.


CONCLUSIONS
Empiric β-lactams was associated with earlier clearance of bacteremia by a median of 1 day compared to vancomycin. Future prospective studies are needed to confirm our findings.
PGY-V Infectious Diseases Residency Training Program, Vancouver General Hospital, University of British Columbia, D 452 Heather Pavilion, 2733 Heather Street, Vancouver, BC, V5Z 1M9, Canada. davie1985@hotmail.com.
Davie
D
Wong
Department of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, BC, Canada.|Medical Microbiology Laboratory, Division of Medical Microbiology and Infection Control, Vancouver General Hospital, JPPN1, 899 W 12th Ave., Vancouver, BC, V5Z 1M9, Canada.
Titus
T
Wong
Department of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, BC, Canada.|Medical Microbiology Laboratory, Division of Medical Microbiology, St. Paul's Hospital, 1081 Burrard St., Vancouver, BC, V6Z 1Y6, Canada.
Marc
M
Romney
Department of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, BC, Canada.|Medical Microbiology Laboratory, Division of Medical Microbiology, St. Paul's Hospital, 1081 Burrard St., Vancouver, BC, V6Z 1Y6, Canada.
Victor
V
Leung
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D016470:Bacteremia / Q000188:drug therapy* / Q000382:microbiology; D005260:Female; D006801:Humans; D008297:Male; D008712:Methicillin / Q000494:pharmacology; D012189:Retrospective Studies; D013203:Staphylococcal Infections / Q000188:drug therapy* / Q000382:microbiology; D013211:Staphylococcus aureus / Q000187:drug effects* / Q000254:growth & development; D016896:Treatment Outcome; D014640:Vancomycin / Q000627:therapeutic use*; D047090:beta-Lactams / Q000627:therapeutic use*
D047090:beta-Lactams; D014640:Vancomycin; D008712:Methicillin
Bacteremia; Beta-lactam; Empiric therapy; Methicillin-susceptible; Staphylococcus aureus; Vancomycin