(p)ppGpp and CodY promoteEnterococcus faecalisvirulence in a murine model of catheter-associated urinary tract infection
AbstractIn Firmicutes, the nutrient-sensing regulators (p)ppGpp, the effector molecule of the stringent response, and CodY work in tandem to maintain bacterial fitness during infection. Here, we tested (p)ppGpp andcodYmutant strains ofEnterococcus faecalisin a catheter-associated urinary tract infections (CAUTI) mouse model and used global transcriptional analysis to investigate the (p)ppGpp and CodY relationship. Absence of (p)ppGpp or single inactivation ofcodYled to lower bacterial loads in catheterized bladders, and diminished biofilm formation on fibrinogen-coated surfaces underin vitroandin vivoconditions. Single inactivation of the bifunctional (p)ppGpp synthetase/hydrolasereldid not affect virulence supporting previous evidence that association of (p)ppGpp with enterococcal virulence is not dependent on activation of the stringent response. Inactivation ofcodYin the (p)ppGpp0strain restoredE. faecalisvirulence in the CAUTI model as well as the ability to form biofilmsin vitro. Transcriptome analysis revealed that inactivation ofcodYrestores, for the most part, the dysregulated metabolism of (p)ppGpp0cells. While a clear linkage between (p)ppGpp and CodY with expression of virulence factors could not be established, targeted transcriptional analysis indicate that a possible association between (p)ppGpp and c-di-AMP signaling pathways in response to the conditions found in the bladder may plays a role in enterococcal CAUTI. Collectively, this study identifies the (p)ppGpp-CodY network as an important contributor to enterococcal virulence in catheterized mouse bladder and supports that basal (p)ppGpp pools and CodY promote virulence through maintenance of a balanced metabolism during adverse conditions.ImportanceCatheter-associated urinary tract infections (CAUTI) are one of the most frequent types of infection found in the hospital setting that can develop into serious and potentially fatal bloodstream infections. One of the infectious agents that frequently cause complicated CAUTI is the bacteriumEnterococcus faecalis, a leading cause of hospital-acquired infections that are often difficult to treat due to the exceptional multidrug resistance of some isolates. Understanding the mechanisms by whichE. faecaliscauses CAUTI will aid in the discovery of new druggable targets to treat these infections. In this study, we report the importance of two nutrient-sensing bacterial regulators, named (p)ppGpp and CodY, for the ability ofE. faecalisto infect the catheterized bladder of mice.