Associations between the genotypes of Staphylococcus aureus bloodstream isolates and clinical characteristics and outcomes of bacteremic patients.
We investigated associations between the genotypic and phenotypic features of Staphylococcus aureus bloodstream isolates and the clinical characteristics of bacteremic patients enrolled in a phase III trial of S. aureus bacteremia and endocarditis. Isolates underwent pulsed-field gel electrophoresis, PCR for 33 putative virulence genes, and screening for heteroresistant glycopeptide intermediate S. aureus (hGISA). A total of 230 isolates (141 methicillin-susceptible S. aureus and 89 methicillin-resistant S. aureus [MRSA]) were analyzed. North American and European S. aureus isolates differed in their genotypic characteristics. Overall, 26% of the MRSA bloodstream isolates were USA 300 strains. Patients with USA 300 MRSA bacteremia were more likely to be injection drug users (61% versus 15%; P < 0.001), to have right-sided endocarditis (39% versus 9%; P = 0.002), and to be cured of right-sided endocarditis (100% versus 33%; P = 0.01) than patients with non-USA 300 MRSA bacteremia. Patients with persistent bacteremia were less likely to be infected with Panton-Valentine leukocidin gene (pvl)-constitutive MRSA (19% versus 56%; P = 0.005). Although 7 of 89 MRSA isolates (8%) exhibited the hGISA phenotype, no association with persistent bacteremia, daptomycin resistance, or bacterial genotype was observed. This study suggests that the virulence gene profiles of S. aureus bloodstream isolates from North America and Europe differ significantly. In this study of bloodstream isolates collected as part of a multinational randomized clinical trial, USA 300 and pvl-constitutive MRSA strains were associated with better clinical outcomes.
Lalani
Tahaniyat
T
Division of Infectious Diseases, Duke University Medical Center, Durham, North Carolina 27710, USA. lalan002@mc.duke.edu
Federspiel
Jerome J
JJ
Boucher
Helen W
HW
Rude
Thomas H
TH
Bae
In-Gyu
IG
Rybak
Michael J
MJ
Tonthat
Giang T
GT
Corey
G Ralph
GR
Stryjewski
Martin E
ME
Sakoulas
George
G
Chu
Vivian H
VH
Alder
Jeff
J
Steenbergen
Judith N
JN
Luperchio
Steven A
SA
Campion
Marilyn
M
Woods
Christopher W
CW
Fowler
Vance G
VG
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D016470:Bacteremia / Q000382:microbiology*; D016521:Electrophoresis, Gel, Pulsed-Field; D004697:Endocarditis, Bacterial / Q000382:microbiology; D005260:Female; D005798:Genes, Bacterial; D005838:Genotype; D006801:Humans; D008297:Male; D055624:Methicillin-Resistant Staphylococcus aureus / Q000235:genetics / Q000472:pathogenicity; D008875:Middle Aged; D010641:Phenotype; D016133:Polymerase Chain Reaction; D013203:Staphylococcal Infections / Q000382:microbiology*; D013211:Staphylococcus aureus / Q000235:genetics* / Q000472:pathogenicity; D016896:Treatment Outcome; D014774:Virulence / Q000235:genetics; D055815:Young Adult