Genomic Analysis of Multiresistant Staphylococcus capitis Associated with Neonatal Sepsis

Area of Science:

• Microbiology
• Genomics
• Infectious Diseases

Background:

• Coagulase-negative staphylococci (CoNS), particularly *Staphylococcus capitis*, are significant causes of bloodstream infections in neonatal intensive care units (NICUs).
• A specific clone, *S. capitis* NRCS-A, has emerged as a global NICU pathogen.
• Understanding the genomic and phenotypic characteristics of *S. capitis* in NICU settings is crucial for infection control.

Purpose of the Study:

• To characterize *Staphylococcus capitis* isolates from New Zealand (NZ) NICUs using whole-genome sequencing (WGS).
• To investigate the phylogenetic relationship, antimicrobial resistance, biofilm formation, and plasmid carriage of NZ NICU *S. capitis* strains.
• To determine the potential reservoir and transmission routes of *S. capitis* within the NICU environment.

Main Methods:

• Whole-genome sequencing (WGS) of 122 *S. capitis* isolates from NZ, supplemented with public data.
• Phylogenetic and comparative genomic analyses.
• Phenotypic assessments of antimicrobial resistance, biofilm formation, and plasmid stability.

Main Results:

• Identification of a distinct *S. capitis* lineage in NZ associated with neonates and the NICU environment.
• This lineage exhibited increased biofilm production, higher chlorhexidine tolerance, and multidrug resistance.
• NZ NICU isolates carried a novel, stably maintained multidrug-resistant plasmid distinct from non-NICU strains.
• Neonatal isolates were indistinguishable from environmental isolates on fomites but distinct from staff carriage isolates.

Conclusions:

• The NICU environment serves as a potential reservoir for neonatal sepsis caused by *S. capitis*.
• Genomic surveillance is vital for tracking and controlling the spread of this pathogen in hospital settings.
• The identified novel plasmid contributes to the multidrug resistance of NICU-associated *S. capitis* strains.