Vandenbroucke-Grauls, C. M. J. E.

bioRxiv2022

Pneumolysin promotes host cell necroptosis and bacterial competence during pneumococcal meningitis as shown by whole animal dual RNA-seq

Pneumolysin is a major virulence factor of Streptococcus pneumoniae that plays a key role in interaction with the host during invasive disease. How pneumolysin influences these dynamics between host and pathogen interaction during early phase of central nervous system infection in pneumococcal meningitis remains unclear. Using a whole animal in vivo dual RNA-seq approach, we identified pneumolysin-specific transcriptional responses in both S. pneumoniae and zebrafish (Danio rerio) during early pneumococcal meningitis. By functional enrichment analysis we identified host pathways known to be activated by pneumolysin, and discovered the importance of necroptosis for host survival. Inhibition of this pathway using the drugs necrostatin-5 or GSK872 increased host mortality during pneumococcal meningitis. On the pathogens side, we find that pneumolysin-dependent competence activation is crucial for intra-host replication and virulence and that not all bacteria activate competence at the same time. Altogether, this study provides new insights into pneumolysin-specific transcriptional responses and identifies key pathways involved in pneumococcal meningitis. GRAPHICAL ABSTRACT O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=200 SRC="FIGDIR/small/479878v1_ufig1.gif" ALT="Figure 1"> View larger version (30K): org.highwire.dtl.DTLVardef@1214d1aorg.highwire.dtl.DTLVardef@14d0e8corg.highwire.dtl.DTLVardef@1f6133aorg.highwire.dtl.DTLVardef@685955_HPS_FORMAT_FIGEXP M_FIG C_FIG HIGHLIGHTSO_LIPneumolysin-specific host and bacterial responses as identified by whole animal dual RNA-seq, available at https://veeninglab.com/dual-danio C_LIO_LIDiscovery of a functional necroptosis or necroptosis-like pathway in zebrafish C_LIO_LIHeterogeneity in competence development during infection C_LIO_LICompetence development is an important virulence determinant C_LI

microbiology↗

bioRxiv2021

Asymptomatic gut colonization by extended-spectrum beta-lactamase-producing Escherichia coli is not associated with an altered gut microbiome or metabolome in Dutch adults

BackgroundGut colonization by antibiotic resistant E. coli strains, including extended-spectrum beta-lactamase (ESBL)-producing E. coli is a risk factor for developing overt infection. The gut microbiome can provide colonization resistance against enteropathogens, but it remains unclear whether it confers resistance against potentially pathogenic ESBL-producing E. coli. MaterialsFrom a Dutch cross-sectional population study (PIENTER-3), feces from 2751 individuals were used to culture ESBL-producing bacteria. Of these, we selected 49 samples which were positive for an ESBL-producing Escherichia coli (ESBL+), and negative for a variety of variables known to affect microbiome composition. These were matched in a 1:1 ratio to ESBL- samples based on age, sex, having been abroad in the past six months and ethnicity. Shotgun metagenomic sequencing was performed and taxonomic species composition and functional annotations (microbial metabolism and carbohydrate-active enzymes) were determined. Targeted quantitative metabolic profiling (1H NMR-spectroscopy) was performed to investigate metabolomic profiles. ResultsNo differences in alpha or beta diversity were observed, nor in relative abundance, between ESBL+ and ESBL- individuals based on bacterial species level composition. Machine learning approaches based on microbiota composition did not accurately predict ESBL status (area under the receiver operating characteristic curve (AUROC)=0.53), neither when based on functional profiles. The metabolome did also not convincingly differ between ESBL groups as assessed by a variety of approaches, including machine learning through random forest (AUROC=0.61). ConclusionUsing a combination of multi-omics and machine learning approaches, we conclude that asymptomatic gut carriage of ESBL-producing E. coli is not associated with an altered microbiome composition or function. This may suggest that microbiome-mediated colonization resistance against ESBL-producing E. coli is not as relevant as it is against other enteropathogens.

microbiology↗