Message: file_get_contents(https://...@gmail.com&api_key=61f08fa0b96a73de8c900d749fcb997acc09): Failed to open stream: HTTP request failed! HTTP/1.1 429 Too Many Requests
is widely recognized as a pathogen with a propensity for acquiring antibiotic resistance. It is capable of causing a range of hospital-acquired infections (urinary tract infections [UTI], pneumonia, sepsis) and community-acquired invasive infections. The genetic heterogeneity of isolates complicates our ability to understand the virulence of Characterization of virulence factors conserved between strains as well as strain-specific factors will improve our understanding of this important pathogen. The MarR family of regulatory proteins is widely distributed in bacteria and regulates cellular processes such as antibiotic resistance and the expression of virulence factors. encodes numerous MarR-like proteins, and they likely contribute to the ability of to respond to and survive under a wide variety of environmental conditions, including those present in the human body. We tested loss-of-function mutations in all the homologues in a murine pneumonia model and found that two ( and ) significantly impacted the virulence of K1 and K2 capsule type hypervirulent () strains and that affected the virulence of a sequence type 258 (ST258) classical strain. In the strains, and mutants displayed phenotypes associated with reduced capsule production, mucoviscosity, and transcription from and promoters that drive expression of capsule synthesis genes. In contrast, and mutants in the ST258 strain had no effect on capsule gene expression or capsule-related phenotypes. Thus, KvrA and KvrB affect virulence in classical and strains but the effect on virulence may not be exclusively due to effects on capsule production. In addition to having a reputation as the causative agent for hospital-acquired infections as well as community-acquired invasive infections, has gained widespread attention as a pathogen with a propensity for acquiring antibiotic resistance. Due to the rapid emergence of carbapenem resistance among strains, a better understanding of virulence mechanisms and identification of new potential drug targets are needed. This study identified two novel regulators (KvrA and KvrB) of virulence in and demonstrated that their effect on virulence in invasive strains is likely due in part to effects on capsule production (a major virulence determinant) and hypermucoviscosity. KvrA also impacts the virulence of classical strains but does not appear to affect capsule gene expression in this strain. KvrA and KvrB are conserved among strains and thus could regulate capsule expression and virulence in diverse strains regardless of capsule type.
