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Silence as a way of niche adaptation: mecC-MRSA with variations in the accessory gene regulator (agr) functionality

Charlotte Huber1, Ivonne Stamm2, Wilma Ziebuhr3

  • 1Advanced Light and Electron Microscopy (ZBS4), Robert Koch Institute, Berlin, Germany.

Scientific Reports
|September 9, 2020
PubMed

Insights

The accessory gene regulator (agr) quorum sensing system in Staphylococcus aureus shows varied functionality, including non-functional variants, across different clonal lineages. Genomic variations in agrA and agrC genes likely drive these adaptations in methicillin-resistant S. aureus (MRSA).

Area of Science:

  • Microbiology
  • Genomics
  • Pathogen Adaptation

Background:

  • The accessory gene regulator (agr) quorum sensing system is crucial for Staphylococcus aureus virulence, influencing acute and chronic infections.
  • Spontaneous agr system alterations are common in human healthcare-associated S. aureus, but data on other lineages are limited.

Purpose of the Study:

  • To investigate agr system functionality and activity in mecC-carrying methicillin-resistant S. aureus (MRSA) from animal and human origins.
  • To correlate genomic variations with observed phenotypic differences in agr activity.

Main Methods:

  • Whole genome analysis to assign isolates to clonal complexes (CC) and agr types.
  • Phenotypic assays and proteome analysis to assess agr functionality and activity levels.
  • Genomic comparison of agr encoding regions (agrA, agrC) to identify variations.

Main Results:

  • Isolates were assigned to four distinct clonal complexes (CC599, CC49, CC130, CC1943) with different agr types.
  • Varied levels of agr activity, including completely non-functional variants, were detected within each CC.
  • Genomic variations in agrA and agrC genes were associated with observed differences in agr functionality.

Conclusions:

  • Agr system variation is prevalent across different S. aureus clonal lineages, including MRSA.
  • Genomic changes in agrA and agrC appear to be key drivers of altered agr functionality.
  • Agr variation may facilitate the adaptation and viability of emerging MRSA lineages in diverse ecological niches.

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