Detectable FITC staining (ND). The spadeletion mutant carrying an expression vector expressing spa from its native promoter (spa) had FITCpositive cells in both conditions constant with this construct making SpA above wt levels. Error bars represent SEM. Information had been analyzed by twotailed Student’s ttest with Bonferroni correction for many testing ( p ). Representative micrographs of wildtype S. aureus cells (blue) in mono (B) versus coculture (C) stained for SpA (yellow) in the cell surface. Scale bars represent . .S. aureus agrDependent Hemolytic Activity Decreases in Response to C. striatumThe other side of agr QSregulated activities in S. aureus is an increase in the production of secreted virulence factors at higher cell density when agr QS is activated (Novick and Geisinger,; Thoendel et al. Hemolysis has traditionally served as an approximation of S. PubMed ID:https://www.ncbi.nlm.nih.gov/pubmed/24683347 aureus virulence issue production and is commonly diminished in agr mutants (Blevins et al. As a result,we assayed for the rabbit erythrocyte hemolytic activity of CFCM from S. aureus grown with or without C. striatum CFCM. Based on our RNAseq data,we predicted that S. aureus exposed to C. striatum would exhibit decreased Doravirine site hemolysin activity due to repression of genes encoding and hemolysins (Table,which are both positively regulated by agr QS. Utilizing a published process (Pang et al,we quantified hemolysis as the loss of optical density at nmFrontiers in Microbiology www.frontiersin.orgAugust Volume ArticleRamsey et al.Staphylococcus aureus Attenuation by CorynebacteriumFIGURE Staphylococcus aureus exhibits decreased hemolytic activity when grown with C. striatum CFCM. Hemolysis of rabbit erythrocytes was quantified m immediately after exposure to BHI,because the negative manage (NC),or CFCM from S. aureus strains grown within the presence of AIP alone or plus the addition of C. striatum CFCM (Cst) for the wildtype (WT) and agrA::Tn mutant (AgrA,n each. Decreased OD is indicative of S. aureus hemolytic activity. Developing S. aureus in the presence of C. striatum CFCM substantially diminished the hemolytic activity developed by the WT. In contrast,the agrA::Tn mutant (AgrA was incapable of substantial hemolysis in either situation. Data were analyzed by twotailed Student’s ttest with Bonferroni correction for several testing ( p p ). Error bars represent SEM.FIGURE Staphylococcus aureus abundance decreases in vivo when coinfected with C. striatum in a murine abscess model. (A) Inside a murine abscess infection model days postinfection,wildtype S. aureus showed reduced numbers (CFUg) in the course of coinfection with C. striatum (light orange bar; Sa Cst) in comparison with monoinfection (orange bar; Sa alone). (B) Within the very same model,C. striatum numbers increased considerably when coinfected with S. aureus (light blue bar; Cst Sa) when in comparison to monoinfection (blue bar; Cst alone). For every bar,n . Information were analyzed using the Mann Whitney Utest ( p p ). Error bars represent SEM.of rabbit erythrocytes when mixed with CFCM harvested from each and every S. aureus strain induced with AIP,in lateexponential phase,within the presence or absence of C. striatum CFCM (Cst). An agrAdeficient mutant served as a nonhemolytic control (Figure ,light gray bars). In this assay,wildtype S. aureus production of hemolytic activity was strongly diminished by exposure to C. striatum CFCM (Figure ,dark gray bars). These final results additional help our hypothesis that S. aureus shifts away from virulence in the presence of C. striatum.infections. S. aureus.