Heterogeneous vancomycin-intermediate susceptibility phenotype in bloodstream methicillin-resistant Staphylococcus aureus isolates from an international cohort of patients with infective endocarditis: prevalence, genotype, and clinical significance.
BACKGROUND
The significance of heterogeneous vancomycin-intermediate Staphylococcus aureus (hVISA) is unknown. Using a multinational collection of isolates from methicillin-resistant S. aureus (MRSA) infective endocarditis (IE), we characterized patients with IE with and without hVISA, and we genotyped the infecting strains.


METHODS
MRSA bloodstream isolates from 65 patients with definite IE from 8 countries underwent polymerase chain reaction (PCR) for 31 virulence genes, pulsed-field gel electrophoresis, and multilocus sequence typing. hVISA was defined using population analysis profiling.


RESULTS
Nineteen (29.2%) of 65 MRSA IE isolates exhibited the hVISA phenotype by population analysis profiling. Isolates from Oceania and Europe were more likely to exhibit the hVISA phenotype than isolates from the United States (77.8% and 35.0% vs 13.9%; P < .001). The prevalence of hVISA was higher among isolates with a vancomycin minimum inhibitory concentration of 2 mg/L (P = .026). hVISA-infected patients were more likely to have persistent bacteremia (68.4% vs 37.0%; P = .029) and heart failure (47.4% vs 19.6%; P = .033). Mortality did not differ between hVISA- and non-hVISA-infected patients (42.1% vs 34.8%, P = .586). hVISA and non-hVISA isolates were genotypically similar.


CONCLUSIONS
In these analyses, the hVISA phenotype occurred in more than one-quarter of MRSA IE isolates, was associated with certain IE complications, and varied in frequency by geographic region.
Bae
In-Gyu
IG
Duke Clinical Research Institute, Durham, North Carolina, USA.
Federspiel
Jerome J
JJ
Miró
José M
JM
Woods
Christopher W
CW
Park
Lawrence
L
Rybak
Michael J
MJ
Rude
Thomas H
TH
Bradley
Suzanne
S
Bukovski
Suzana
S
de la Maria
Cristina Garcia
CG
Kanj
Souha S
SS
Korman
Tony M
TM
Marco
Francesc
F
Murdoch
David R
DR
Plesiat
Patrick
P
Rodriguez-Creixems
Marta
M
Reinbott
Porl
P
Steed
Lisa
L
Tattevin
Pierre
P
Tripodi
Marie-Françoise
MF
Newton
Karly L
KL
Corey
G Ralph
GR
Fowler
Vance G
VG
D000368:Aged; D016470:Bacteremia / Q000188:drug therapy / Q000235:genetics / Q000382:microbiology; D024901:Drug Resistance, Multiple, Bacterial / Q000235:genetics; D004697:Endocarditis, Bacterial / Q000188:drug therapy* / Q000453:epidemiology / Q000382:microbiology; D005260:Female; D005838:Genotype; D014943:Global Health; D006801:Humans; D008297:Male; D055624:Methicillin-Resistant Staphylococcus aureus / Q000187:drug effects / Q000235:genetics*; D008826:Microbial Sensitivity Tests; D008875:Middle Aged; D010641:Phenotype; D010802:Phylogeny; D011159:Population Surveillance; D015995:Prevalence; D013203:Staphylococcal Infections / Q000188:drug therapy* / Q000453:epidemiology / Q000382:microbiology; D020713:Vancomycin Resistance / Q000187:drug effects / Q000235:genetics*