Staphylococcus lugdunensis: a Skin Commensal with Invasive Pathogenic Potential

Area of Science:

• Microbiology
• Infectious Diseases
• Bacterial Pathogenesis

Background:

• * Staphylococcus lugdunensis (S. lugdunensis) is a coagulase-negative staphylococcus (CoNS) species causing severe human infections, often mistaken for Staphylococcus aureus (S. aureus).
• * Recent advancements in matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) have improved diagnostic accuracy, distinguishing S. lugdunensis from S. aureus.
• * S. lugdunensis possesses various virulence factors for adhesion, cytotoxicity, and immune evasion, though less diverse than S. aureus.

Purpose of the Study:

• * To elucidate the distinct virulence mechanisms and pathogenic potential of S. lugdunensis.
• * To understand the interactions of S. lugdunensis with host cells and the microbiome.
• * To evaluate the implications of S. lugdunensis's virulence for its potential use as a probiotic.

Main Methods:

• * Comparative analysis of virulence factor diversity between S. lugdunensis and S. aureus.
• * Investigation of S. lugdunensis's heme extraction mechanisms (Isd system and ECF).
• * Characterization of S. lugdunensis synergistic hemolysins (SLUSH) and the peptide antibiotic lugdunin.
• * Examination of bacterial adherence mechanisms in endovascular infections.
• * Study of S. lugdunensis survival and release mechanisms within macrophages, contrasting with S. aureus.

Main Results:

• * S. lugdunensis utilizes an iron-regulated surface determinant (Isd) system and an energy-coupling factor (ECF) mechanism for heme acquisition.
• * Small cytolytic S. lugdunensis synergistic hemolysins (SLUSH) and β-toxin synergistically lyse erythrocytes.
• * S. lugdunensis produces lugdunin, a novel peptide antibiotic affecting nasal and skin microbiota.
• * Adherence in endovascular infections involves clumping factor A homologue and an uncharacterized mechanism for von Willebrand factor interaction.
• * S. lugdunensis survives within phagolysosomes and is released upon macrophage apoptosis, differing from S. aureus's intracellular growth and leukotoxin activity.

Conclusions:

• * S. lugdunensis possesses a unique set of virulence factors and pathogenic strategies distinct from S. aureus.
• * Its ability to survive within macrophages and produce antimicrobial peptides highlights its complex role in infections and host interactions.
• * Despite potential probiotic applications, the inherent virulence of S. lugdunensis necessitates further research into its colonization, pathogenicity, and microbiome dynamics.