Staphylococcus epidermidis MSCRAMM SesJ Is Encoded in Composite Islands

Area of Science:

• Microbiology
• Genetics
• Infectious Diseases

Background:

• Staphylococcus epidermidis is a major cause of hospital-acquired infections, particularly in immunocompromised patients and those with medical devices.
• Most clinical isolates are methicillin-resistant and possess mobile genetic elements (MGEs) that can carry virulence and resistance genes.
• The microbial surface component recognizing adhesive matrix molecule (MSCRAMM) group includes key virulence factors in pathogenic bacteria.

Purpose of the Study:

• To investigate the genomic location and context of the sesJ gene, encoding a recently discovered S. epidermidis surface protein (SesJ).
• To determine if SesJ, an MSCRAMM, is located within MGEs in clinical isolates of S. epidermidis.
• To understand the implications of SesJ's presence in MGEs for pathogen adaptation and virulence.

Main Methods:

• Analysis of sesJ gene presence and its flanking regions in S. epidermidis clinical isolates.
• Identification of MGEs associated with the sesJ gene, specifically the arginine catabolic mobile element (ACME) and staphylococcal cassette chromosome (SCC) element.
• Characterization of the specific insertion sites (DR_B and DR_E) and associated genes within these MGEs.

Main Results:

• The sesJ gene is consistently found alongside glycosyltransferase genes (gtfA and gtfB) within two distinct MGEs: ACME and SCC.
• SesJ insertion into the SCC element occurs via DR_E, while insertion into ACME, along with a type 1 restriction-modification system, occurs via DR_B.
• The ACME and SCC elements encode different isoforms of the SesJ protein, indicating strain-specific variations.

Conclusions:

• This study reports, for the first time, the presence of an MSCRAMM (SesJ) within MGEs in S. epidermidis clinical isolates.
• The location of SesJ on MGEs suggests a mechanism for rapid dissemination of virulence factors, contributing to S. epidermidis's adaptability and pathogenicity.
• Understanding the role of MGEs in carrying virulence factors is crucial for developing strategies against emerging infectious diseases caused by adaptable pathogens.