Population structure of Enterococcus faecium causing bacteremia in a Spanish university hospital: setting the scene for a future increase in vancomycin resistance?
Over an 8-year period (1995 to 2002), 86 Enterococcus faecium blood isolates from 84 patients, of which 54 were ampicillin resistant (AREF) and 32 were ampicillin susceptible (ASEF), were studied in a university hospital (1,200 beds; serving a population of 600,000) in Spain, a country characterized by a near-absence of resistance to vancomycin and very high rates of ampicillin resistance among enterococci. Clonal relatedness by pulsed-field gel electrophoresis (PFGE), antibiotic susceptibility, presence of the virulence/epidemicity genes esp(Efm) and hyl(Efm), and identification of purK alleles were studied. A group of isolates was also analyzed by amplified fragment length polymorphism (AFLP) and multilocus sequence typing. Medical charts (30 variables collected) were reviewed for 60/84 patients. ASEF showed high clonal diversity (32 PFGE types, 11 purK alleles, 4 AFLP genogroups), did not harbor putative virulence genes, and had no specific association with hospital acquisition. AREF isolates belonged to a clonal complex (CC) of genetically related strains (purK-1, AFLP genogroup C), occasionally harboring putative virulence traits, and were from patients with particular risk factors. Within this CC, previously associated with vancomycin-resistant E. faecium isolates causing outbreaks worldwide (W. L. Homan et al., J. Clin. Microbiol. 40:1963-1971, 2002), a great genetic diversity of antibiotic resistance and virulence/epidemicity profiles was found. Associations between esp and a >7-day hospital stay and between purK-1, hospital location, and nosocomial acquisition were noted (P < 0.001). These findings reflect the importance of local environmental differences in the evolution of this CC, suggesting that the emergence of vancomycin resistance among AREF strains in Spain may be a question of time.
Coque
Teresa M
TM
Departamento de Microbiologíca, Servicio de Microbiología, Hospital Universitario Ramón y Cajal, Carretera de Colmenar, km. 9.1, Madrid 28034, Spain. mcoque.hrc@salud.madrid.org
Willems
Rob J L
RJ
Fortún
Jesús
J
Top
Janetta
J
Diz
Sergio
S
Loza
Elena
E
Cantón
Rafael
R
Baquero
Fernando
F
D000667:Ampicillin / Q000494:pharmacology; D000668:Ampicillin Resistance; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D016470:Bacteremia / Q000453:epidemiology* / Q000382:microbiology*; D001426:Bacterial Proteins / Q000235:genetics; D016984:Enterococcus faecium / Q000145:classification* / Q000187:drug effects / Q000235:genetics* / Q000472:pathogenicity; D019143:Evolution, Molecular; D016908:Gram-Positive Bacterial Infections / Q000453:epidemiology / Q000382:microbiology; D006785:Hospitals, University; D006801:Humans; D008826:Microbial Sensitivity Tests; D013030:Spain / Q000453:epidemiology; D020713:Vancomycin Resistance; D014774:Virulence
D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D000667:Ampicillin