Single-cell approach dissecting agr quorum sensing dynamics in Staphylococcus aureus

Abstract

Staphylococcus aureus both colonizes humans and causes severe virulent infections. Virulence is regulated by the agr quorum sensing system and its autoinducing peptide (AIP), with dynamics at the single-cell level across four agr-types - each defined by distinct AIP sequences and capable of cross-inhibition - remaining elusive. Employing microfluidics, time-lapse microscopy, and deep-learning image analysis, we uncovered significant differences in AIP sensitivity among agr-types. We observed bimodal agr activation, attributed to intergenerational phenotypic stability and influenced by AIP concentration. Upon AIP stimulation, agr-III showed AIP insensitivity, while agr-II exhibited increased sensitivity and prolonged generation time. Beyond expected cross-inhibition of agr-I by heterologous AIP-II and -III, the presumably cross-activating AIP-IV also inhibited agr-I. Community interactions across different agr-type pairings revealed four main patterns: stable or switched dominance, and delayed or stable dual activation, influenced by community characteristics. These insights underscore the potential of personalized treatment strategies considering virulence and genetic diversity.