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Large clonal outbreak of multidrug-resistant CC17 ST17 Enterococcus faecium containing Tn5382 in a Spanish hospital

Sylvia Valdezate1, Cristina Labayru, Ana Navarro

  • 1Departamento de Bacteriología, Centro Nacional de Microbiología, Instituto de Salud Carlos III, Majadahonda, Madrid, Spain. svaldezate@isciii.es

The Journal of Antimicrobial Chemotherapy
|November 13, 2008
PubMed
Abstract

Insights

A clonal outbreak of multidrug-resistant Enterococcus faecium (CC17 ST17) carrying Tn5382 was identified in a Spanish hospital. This persistent clone, found in both hospital and community settings, may increase vancomycin-resistant enterococci prevalence.

Area of Science:

  • Microbiology
  • Infectious Diseases
  • Genetics

Background:

  • Enterococcus faecium is a significant cause of hospital-acquired infections.
  • Multidrug resistance in E. faecium, particularly vancomycin resistance, poses a major public health threat.
  • Clonal spread of specific E. faecium strains contributes to the dissemination of antibiotic resistance.

Purpose of the Study:

  • To characterize a large clonal outbreak of multidrug-resistant Enterococcus faecium (E. faecium) in a Spanish hospital.
  • To investigate the genetic basis of antibiotic resistance and virulence in the outbreak strain.
  • To assess the potential impact of this clone on the prevalence of vancomycin-resistant enterococci.

Main Methods:

  • Molecular typing of E. faecium isolates using pulsed-field gel electrophoresis (PFGE), multiple-locus variable-number tandem-repeat analysis (MLVA), and multilocus sequence typing (MLST).
  • Analysis of genes encoding resistance to ampicillin, aminoglycosides, macrolides, quinupristin/dalfopristin, quinolones, and tetracycline.
  • Identification and characterization of mobile genetic elements, including Tn5382, and virulence factors such as esp and hyl.

Main Results:

  • All isolates belonged to a single clone, identified as CC17 ST17 by MLST and MT1 by MLVA, exhibiting highly similar PFGE profiles.
  • The vancomycin-resistant E. faecium isolates carried the Tn5382 element linked to the pbp5 gene, with specific mutations in the vanS(B)-vanY(B) intergenic region.
  • Multiple resistance genes (erm(B), mef(E), tet(M), ant(6')-Ia, aph(3')-IIIa, aac(6')-Ie-aph(2'')-Ia) were identified, along with high-level ciprofloxacin resistance due to specific mutations in ParC and GyrA. The esp gene was universally present, while hyl was variable.

Conclusions:

  • A large clonal outbreak caused by multidrug-resistant CC17 E. faecium harboring pbp5-Tn5382 was described.
  • The persistence of this clone since 2005 in both hospital and community settings, coupled with the potential transfer of Tn5382 to other epidemic strains, may increase vancomycin-resistant enterococci prevalence.
  • This study reports the first description of the mef(E) gene in E. faecium.

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