Biology subjects

Bruisten, S.

Publications and source records attributed to Bruisten, S..

3 recordsLinked to original sources

bioRxiv2023

The inter-continental population dynamics of Neisseria gonorrhoeae

Neisseria gonorrhoeae is a globally distributed sexually transmitted bacterial pathogen. Recent studies have revealed that its evolution has been shaped by antibiotic use, while molecular surveillance efforts have demonstrated large changes in lineage composition over relatively short time-spans. However, the global population dynamics of N. gonorrhoeae remain unsatisfyingly characterized. To reconstruct recent large-scale population dynamics, we generated a dated phylogeny from 9,732 N. gonorrhoeae genomes and found the effective population size of the species to have expanded gradually over the past two centuries. While the effective population size of clades with reduced susceptibility to extended-spectrum cephalosporins started declining around 2010, a major clade containing a mosaic mtr operon associated with cephalosporin susceptibility and decreased azithromycin did not display any reduction in population size. Using ancestral trait reconstruction analyses, we delineated transmission lineages, defined as groups of sequences in which all the samples can be traced back to the same import event to a given location. Import, export and local transmission dynamics across two densely sampled locations (Norway and Victoria, Australia) were investigated in detail. Norway exhibited substantially higher rates of strain import and export compared to Victoria, where incidence was to a larger extent fuelled by locally transmitted lineages. Taken together, our work highlights the power of large-scale phylogenomic analyses to uncover the complex dynamics of lineage transmission in N. gonorrhoeae.

microbiology↗

bioRxiv2023

Bacterial vaginosis is associated with increased amylolytic activity

This study investigates the degradation of resistant -1,4-glucan by vaginal bacterial species, with a focus on Gardnerella spp., to elucidate its role in bacterial vaginosis (BV). The ability of Gardnerella vaginalis, Gardnerella swidsinskii, Gardnerella leopoldii, Gardnerella piotii, Lactobacillus iners, and Lactobacillus crispatus was assessed to metabolize an ungelatinized, labeled form of raw amylose, a degradation-resistant -1,4-glucan. The enzymatic activity of these species was evaluated in vitro, and its association with BV was examined in vaginal swabs. Gardnerella vaginalis, G. swidsinskii, and G. leopoldii demonstrated the best ability to degrade resistant -1,4-glucan in vitro. Unlike the cell-bound, S-layer-associated glycogen-degrading activity in L. crispatus, this -glucosidase activity in Gardnerella was also extracellular, but not cell-bound and not repressed by glucose. Vaginal swabs showing high rates of resistant -1,4-glucan degradation activity were associated with BV, particularly in the concurrent presence of G. leopoldii, G. swidsinskii, and G. vaginalis. These findings suggest a role of -1,4-glucan degradation in BV pathogenesis mediated by Gardnerella species. The results indicate the potential of targeting bacterial amylase activity as therapeutic strategy for BV prevention and treatment.

microbiology↗

bioRxiv2018

Comparative genomics of human Lactobacillus crispatus isolates reveals genes for glycosylation and glycogen degradation: Implications for in vivo dominance of the vaginal microbiota

BackgroundA vaginal microbiota dominated by lactobacilli (particularly Lactobacillus crispatus) is associated with vaginal health, whereas a vaginal microbiota not dominated by lactobacilli is considered dysbiotic. Here we investigated whether L. crispatus strains isolated from the vaginal tract of women with Lactobacillus-dominated vaginal microbiota (LVM) are pheno- or genotypically distinct from L. crispatus strains isolated from vaginal samples with dysbiotic vaginal microbiota (DVM).\n\nResultsWe studied 33 L. crispatus strains (n=16 from LVM; n=17 from DVM). Comparison of these two groups of strains showed that, although strain differences existed, both groups were heterofermentative, produced similar amounts of organic acids, inhibited Neisseria gonorrhoeae growth and did not produce biofilms. Comparative genomics analyses of 28 strains (n=12 LVM; n=16 DVM) revealed a novel, 3-fragmented glycosyltransferase gene that was more prevalent among strains isolated from DVM. Most L. crispatus strains showed growth on glycogen-supplemented growth media. Strains that showed less efficient (n=6) or no (n=1) growth on glycogen all carried N-terminal deletions (respectively, 29 and 37 amino acid-deletions) in a putative pullulanase type I gene.\n\nDiscussionL. crispatus strains isolated from LVM were not phenotypically distinct from L. crispatus strains isolated from DVM, however, the finding that the latter were more likely to carry a 3-fragmented glycosyltransferase gene may indicate a role for cell surface glycoconjugates, which may shape vaginal microbiota-host interactions. Furthermore, the observation that variation in the pullulanase type I gene associated with growth on glycogen discourages previous claims that L. crispatus cannot directly utilize glycogen.

microbiology↗