Biology subjects

Cook, L. C.

Publications and source records attributed to Cook, L. C..

4 recordsLinked to original sources

bioRxiv2026

Biofilm dispersion in Enterococcus faecalis is mediated by nutrient step-change and intra-species signaling

Enterococcus faecalis is a Gram-positive intestinal commensal and opportunistic pathogen capable of causing serious infections, including urinary tract infections, endocarditis, and wound infections. A major contributor to its persistence during infection is the ability to form biofilms on host tissues and medical devices. Biofilm cells have higher phenotypic tolerance to antimicrobial treatment than planktonic bacteria. While mechanisms governing biofilm assembly in E. faecalis have been widely studied, the processes that regulate biofilm dispersion, the final stage of the biofilm life cycle, remain poorly understood. In this study, we found that dispersion is triggered by a tenfold step-change increase in nutrient availability and by cell free supernatant (CFS) of E. faecalis OG1RF cultures. Cells released from biofilms regain sensitivity to antibiotics similar to planktonic cells but maintain a high potential for adherence. We characterized the glycosyltransferase epaOX, which contributes to the structure of the enterococcal polysaccharide antigen as necessary for nutrient step-change induced dispersion, CFS induced dispersion, and adhesion of dispersed cells. Supplementation of epaOX mutant CFS with galactose and N-acetylgalactosamine was sufficient to restore CFS induced dispersion. Together these data suggest that dispersion in OG1RF occurs with fast kinetics, affects antibiotic sensitivity and is regulated in part by known virulence factors. ImportanceE. faecalis causes difficult to treat infections at numerous body sites in human patients. E. faecalis biofilms are adherent populations that require high levels of antibiotics for treatment. Biofilms undergo a disassembly process named dispersion that allows individual cells to leave the biofilm and colonize new locations. Dispersed cells in other species are killed by lower amounts of antibiotics than biofilm cells. Here we showed that dispersion occurs in E. faecalis and lowers the level of antibiotics needed to kill dispersed cells. Dispersion triggers could be used in the future to design treatments that increase the effectiveness of antibiotics.

microbiology↗

bioRxiv2026

Contact dependent suppression of Clostridioides difficile sporulation by enterococci requires the endocarditis and biofilm pilus

Clostridioides difficile is a healthcare-associated infection that arises when broad-spectrum antibiotic treatment disrupts the gut microbiota and is transmitted by highly resistant spores. Vancomycin-resistant Enterococcus faecium (VRE) is an opportunistic pathogen frequently co-isolated from C. difficile patients. We found that C. difficile sporulation is significantly reduced in VRE-C. difficile co-culture. Physical separation of C. difficile and VRE in transwell co-culture restored sporulation. Mixed macrocolony culture assays on solid agar confirmed physical contact is necessary for sporulation inhibition. We screened a panel of enterococci and found that most strains reduce sporulation, except Enterococcus saccharolyticus, which lacks predicted surface displayed virulence factors in its genome. We performed a candidate gene screen using an Enterococcus faecalis OG1RF transposon library and found that an insertion in the major pilin ebpC partially restored C. difficile sporulation in co-culture. These data were confirmed with in-frame deletions in the ebpABC pilus operon and a clinical isolate of E. feacalis lacking ebpABC. These findings suggest enterococci modulate C. difficile sporulation through a contact-dependent mechanism involving the Ebp pilus. ImportanceA characteristic of C. difficile infection is multiple episodes of acute disease. Spores are the transmission vector of C. difficile and are necessary for recurrence in models of disease. Our research demonstrates that C. difficile spore production is significantly reduced in the presence of enterococci, a common group of beneficial and pathogenic bacteria present in the gut microbiota. Physical contact with enterococci reduces C. difficile spore production. We attribute this effect to a protein structure on the surface of enterococci. This finding suggests a potential role for enterococci and the gut microbiota in general to uncover regulators of C. difficile spore formation. This may provide an avenue for innovative treatment strategies that reduce spore formation.

microbiology↗

bioRxiv2022

A novel conserved protein in Streptococcus agalactiae, BvaP, is important for vaginal colonization and biofilm formation

Streptococcus agalactiae (Group B Strep, GBS) infections in neonates are often fatal and strongly associated with maternal GBS vaginal colonization. Here, we investigated the role of a previously uncharacterized protein, BvaP, in GBS vaginal colonization. BvaP was previously identified as the most highly upregulated gene in the GBS A909 transcriptome when comparing vaginal colonization to growth in liquid culture. We found that expression of BvaP affects GBS adherence to extracellular matrix components and human vaginal epithelial cells and a{Delta} bvaP mutant was significantly decreased in its ability to colonize the murine vaginal tract. Cellular morphological alterations such as changes in cell shape, chain length, and clumping were also observed in a knockout mutant strain. Given its high expression in vivo, high degree of conservation among GBS strains, and role in vaginal colonization, BvaP may be an eligible target for GBS vaccination and/or drug therapy. IMPORTANCENeonatal GBS disease is a major cause of morbidity and mortality and maternal vaginal colonization is the leading risk factor for disease. Colonization prevention would greatly impact rates of disease transmission, but vaccine development has stalled as capsular polysaccharide vaccines have low immunogenicity in vivo. While these vaccines are still in development, addition of a protein conjugate may prove fruitful in increasing immunogenicity and strain coverage across GBS serotypes. Previous research identified sak_1753 as a gene very highly upregulated gene during murine vaginal colonization. This study reveals that Sak_1753 is required to maintain proper GBS cellular morphology and colonization phenotypes and is required for in vivo vaginal colonization in a murine model. We have renamed Sak_1753 Group B Strep vaginal adherence protein (BvaP). The findings of this study indicate that BvaP is important in GBS colonization of the vaginal tract and may be a candidate for vaccine development.

microbiology↗

bioRxiv2019

Loss of microbial diversity and body site heterogeneity in individuals with Hidradenitis Suppurativa

Hidradenitis Suppurativa (HS) is a chronic, scarring, inflammatory skin disease affecting hair follicles in axillae, inguinal, and anogenital regions. Dysbiosis in HS patients compared to healthy subjects is documented. However, whether dysbiosis is specific to particular body sites or skin niches is unknown. We investigated the follicular and skin surface microbiome of the axilla and groin of HS patients (n=11) and healthy individuals (n=10) using 16S rRNA gene sequencing (V3-V4). We sampled non-lesional (HSN) and lesional skin (HSL) of HS patients. {beta}-diversity was significantly decreased (p<0.05) in HSN and HSL skin compared to normal skin with loss of body site and skin niche heterogeneity in HS samples. The relative bacterial abundance of specific microbes was also significantly different between normal and HSN (15 genera) or HSL (21 genera) skin. Smoking and alcohol use influenced the {beta}-diversity (p<0.08) in HS skin. We investigated metabolic profiles of bacterial communities in HS and normal skin using a computational approach. Metabolism, Genetic Information Processing, and Environmental Information Processing were significantly different between normal and HS samples. Altered metabolic pathways associated with dysbiosis of HS skin suggest mechanisms underlying the disease pathology and information about treatment with drugs targeting those pathways.

microbiology↗