title: Clinical implications of varying degrees of vancomycin susceptibility in methicillin-resistant Staphylococcus aureus bacteremia.
abstract: We conducted a retrospective study of the clinical aspects of bacteremia caused by methicillin-resistant Staphylococcus aureus (MRSA) with heterogeneously reduced susceptibility to vancomycin. Bloodstream MRSA isolates were screened for reduced susceptibility by using brain-heart infusion agar, including 4 mg/L vancomycin with and without 4% NaCl. Patients whose isolates exhibited growth (case-patients) were compared with those whose isolates did not (controls) for demographics, coexisting chronic conditions, hospital events, antibiotic exposures, and outcomes. Sixty-one (41%) of 149 isolates exhibited growth. Subclones from 46 (75%) of these had a higher MIC of vancomycin than did their parent isolates. No isolates met criteria for vancomycin heteroresistance. No differences in potential predictors or in outcomes were found between case-patients and controls. These data show that patients with vancomycin-susceptible MRSA bacteremia have similar baseline clinical features and outcomes whether or not their bacterial isolates exhibit growth on screening media containing vancomycin.
authors.affiliation: Beth Israel Deaconess Medical Center, Boston, Massachusetts, USA. mschwabe@bidmc.harvard.edu
authors.forename: Mitchell J
authors.initials: MJ
authors.lastname: Schwaber
authors.forename: Sharon B
authors.initials: SB
authors.lastname: Wright
authors.forename: Yehuda
authors.initials: Y
authors.lastname: Carmeli
authors.forename: Lata
authors.initials: L
authors.lastname: Venkataraman
authors.forename: Paola C
authors.initials: PC
authors.lastname: DeGirolami
authors.forename: Aneta
authors.initials: A
authors.lastname: Gramatikova
authors.forename: Trish M
authors.initials: TM
authors.lastname: Perl
authors.forename: George
authors.initials: G
authors.lastname: Sakoulas
authors.forename: Howard S
authors.initials: HS
authors.lastname: Gold
mesh_terms: D016470:Bacteremia / Q000175:diagnosis / Q000188:drug therapy*; D015331:Cohort Studies; D016521:Electrophoresis, Gel, Pulsed-Field; D005260:Female; D006760:Hospitalization; D006801:Humans; D008297:Male; D016106:Methicillin Resistance; D008826:Microbial Sensitivity Tests; D012189:Retrospective Studies; D013203:Staphylococcal Infections / Q000175:diagnosis / Q000188:drug therapy*; D013211:Staphylococcus aureus / Q000187:drug effects* / Q000235:genetics / Q000302:isolation & purification / Q000472:pathogenicity; D014640:Vancomycin / Q000008:administration & dosage / Q000494:pharmacology*; D020713:Vancomycin Resistance
chemical_list: D014640:Vancomycin