Emergence of clonal complex 17 Enterococcus faecium in The Netherlands

Area of Science:

• Microbiology
• Infectious Diseases
• Epidemiology

Background:

• Vancomycin-resistant Enterococcus faecium (VRE) emergence is linked to clonal complex 17 (CC17).
• CC17 E. faecium is characterized by quinolone and ampicillin resistance, often with the enterococcal surface protein (esp) gene.
• An increase in vancomycin-susceptible CC17 E. faecium infections prompted a national study.

Purpose of the Study:

• To investigate ecological changes in enterococcal infections nationwide.
• To determine the prevalence and clonal spread of ampicillin-resistant E. faecium (AREF).
• To identify the genetic characteristics of AREF isolates, including CC17 and the esp gene.

Main Methods:

• Data and strains collected from 66 microbiology laboratories across The Netherlands.
• E. faecium and E. faecalis identified by multiplex PCR.
• E. faecium isolates genotyped using multiple-locus variable-number tandem-repeat analysis (MLVA); esp gene presence confirmed by PCR.

Main Results:

• Ampicillin-resistant enterococcal isolates from sterile sites increased significantly from 1994 to 2005.
• Proportion of AREF among enterococcal bloodstream infections rose from 4% to 20% (P < 0.001).
• 86% of AREF isolates belonged to CC17, with four dominant MLVA types accounting for 64% of cases, often associated with the esp gene.

Conclusions:

• Infections caused by CC17 E. faecium have increased nationwide, particularly in university hospitals.
• The clonal spread of specific CC17 MLVA types is driving this increase.
• Acquisition of the esp gene appears associated with the rise of CC17 E. faecium infections.