Influence of vancomycin minimum inhibitory concentration on the outcome of methicillin-susceptible Staphylococcus aureus left-sided infective endocarditis treated with antistaphylococcal β-lactam antibiotics: a prospective cohort study by the International Collaboration on Endocarditis.
OBJECTIVE
Left-sided methicillin-susceptible Staphylococcus aureus (MSSA) endocarditis treated with cloxacillin has a poorer prognosis when the vancomycin minimum inhibitory concentration (MIC) is ≥1.5 mg/L. We aimed to validate this using the International Collaboration on Endocarditis cohort and to analyse whether specific genetic characteristics were associated with a high vancomycin MIC (≥1.5 mg/L) phenotype.


METHODS
All patients with left-sided MSSA infective endocarditis treated with antistaphylococcal β-lactam antibiotics between 2000 and 2006 with available isolates were included. Vancomycin MIC was determined by Etest as either high (≥1.5 mg/L) or low (<1.5 mg/L). Isolates underwent spa typing to infer clonal complexes and multiplex PCR for identifying virulence genes. Univariate analysis was performed to evaluate the association between in-hospital and 1-year mortality, and vancomycin MIC phenotype.


RESULTS
Sixty-two cases met the inclusion criteria. Vancomycin MIC was low in 28 cases (45%) and high in 34 cases (55%). No significant differences in patient demographic data or characteristics of infection were observed between patients with infective endocarditis due to high and low vancomycin MIC isolates. Isolates with high and low vancomycin MIC had similar distributions of virulence genes and clonal lineages. In-hospital and 1-year mortality did not differ significantly between the two groups (32% (9/28) vs. 27% (9/34), p 0.780; and 43% (12/28) vs. 29% (10/34), p 0.298, for low and high vancomycin MIC respectively).


CONCLUSIONS
In this international cohort of patients with left-sided MSSA endocarditis treated with antistaphylococcal β-lactams, vancomycin MIC phenotype was not associated with patient demographics, clinical outcome or virulence gene repertoire.
Infectious Diseases Service, Hospital Clinic of Barcelona, Institut d'Investigacions Biomèdiques Pi i Sunyer (IDIBAPS), Barcelona, Spain.
J M
JM
Pericàs
Division of Infectious Diseases and International Health, Duke University Medical Center, Durham, NC, USA; Duke Clinical Research Institute, Durham, NC, USA.
J A
JA
Messina
Infectious Diseases Service, Hospital Clinic of Barcelona, Institut d'Investigacions Biomèdiques Pi i Sunyer (IDIBAPS), Barcelona, Spain.
C
C
Garcia-de-la-Mària
Division of Infectious Diseases and International Health, Duke University Medical Center, Durham, NC, USA; Duke Global Health Institute, Durham, NC, USA.
L
L
Park
Division of Infectious Diseases and International Health, Duke University Medical Center, Durham, NC, USA.
B K
BK
Sharma-Kuinkel
Department of Microbiology, Institute for Global Health, Hospital Clinic of Barcelona, University of Barcelona, Barcelona, Spain.
F
F
Marco
Infectious Disease Division, Medical University of South Carolina, Charleston, SC, USA.
D
D
Wray
Division of Infectious Diseases, American University of Beirut, Beirut, Lebanon.
Z A
ZA
Kanafani
Division of Infectious Diseases and International Health, Duke University Medical Center, Durham, NC, USA.
M
M
Carugati
Internal Medicine, Department of Clinical and Experimental Medicine, University of Campania 'Luigi Vanvitelli', Italy; Unit of Infectious and Transplant Medicine, 'V. Monaldi' Hospital, AORN dei Colli, Naples, Italy.
E
E
Durante-Mangoni
Infectious Diseases and Intensive Care Unit, Pontchaillou University Hospital, Rennes, France.
P
P
Tattevin
Division of Infectious Diseases and International Health, Duke University Medical Center, Durham, NC, USA; Duke Clinical Research Institute, Durham, NC, USA.
V H
VH
Chu
Infectious Diseases Service, Hospital Clinic of Barcelona, Institut d'Investigacions Biomèdiques Pi i Sunyer (IDIBAPS), Barcelona, Spain.
A
A
Moreno
Division of Infectious Diseases and International Health, Duke University Medical Center, Durham, NC, USA; Duke Clinical Research Institute, Durham, NC, USA.
V G
VG
Fowler
Infectious Diseases Service, Hospital Clinic of Barcelona, Institut d'Investigacions Biomèdiques Pi i Sunyer (IDIBAPS), Barcelona, Spain. Electronic address: jmmiro@ub.edu.
J M
JM
Miró
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000900:Anti-Bacterial Agents / Q000494:pharmacology* / Q000627:therapeutic use*; D004697:Endocarditis, Bacterial / Q000188:drug therapy* / Q000382:microbiology / Q000401:mortality; D005260:Female; D006801:Humans; D008297:Male; D008826:Microbial Sensitivity Tests; D008875:Middle Aged; D058889:Molecular Typing; D060885:Multiplex Polymerase Chain Reaction; D011446:Prospective Studies; D013203:Staphylococcal Infections / Q000188:drug therapy* / Q000382:microbiology; D013211:Staphylococcus aureus / Q000145:classification / Q000187:drug effects* / Q000235:genetics / Q000302:isolation & purification; D016019:Survival Analysis; D016896:Treatment Outcome; D014640:Vancomycin / Q000494:pharmacology*; D037521:Virulence Factors / Q000235:genetics; D047090:beta-Lactams / Q000627:therapeutic use*
D000900:Anti-Bacterial Agents; D037521:Virulence Factors; D047090:beta-Lactams; D014640:Vancomycin
Endocarditis; Genotype; Phenotype; Staphylococcus aureus; Vancomycin MIC