Five genes encoding surface-exposed LPXTG proteins are enriched in hospital-adapted Enterococcus faecium clonal...

Area of Science:

• Microbiology
• Genetics
• Infectious Diseases

Background:

• Enterococcus faecium is a significant cause of hospital-acquired infections.
• Clonal complex 17 (CC17) is a distinct genetic subpopulation of E. faecium associated with outbreaks and invasive infections.
• The evolution of CC17 is thought to involve the acquisition of genes conferring antibiotic resistance, metabolic advantages, and virulence.

Purpose of the Study:

• To identify surface-exposed LPXTG cell wall-anchored proteins (CWAPs) specifically enriched in CC17 E. faecium.
• To understand the genetic basis for the emergence and adaptation of CC17 as a nosocomial pathogen.

Main Methods:

• Screening of 131 E. faecium isolates (40 CC17, 91 non-CC17) for 22 putative CWAP genes using PCR and hybridization techniques.
• Analysis of gene distribution, clustering, and expression (mRNA).
• Immunotransmission electron microscopy to visualize protein localization and minimal spanning tree analysis to assess gene transfer.

Main Results:

• Five LPXTG surface protein genes were found to be significantly enriched in CC17 isolates (70-100% of CC17 vs. 8-26% of non-CC17).
• Three of these genes clustered together, potentially forming a novel enterococcal pathogenicity island.
• Expression of these proteins was confirmed, and they were localized to the cell wall.
• Horizontal gene transfer of CWAP genes was suggested by clustering analysis, indicating a role in hospital adaptation.

Conclusions:

• Specific LPXTG CWAPs are key genetic determinants enriched in the CC17 E. faecium subpopulation.
• These CWAPs likely contribute to the adaptation and success of CC17 in hospital environments.
• The findings provide insight into the evolution and pathogenicity of this important nosocomial pathogen.