Summary of - Emerging pathogens in planetary health and lessons from comparative genome analyses of three Clostridia species

Document Type

Article

Abstract

The research article titled “Emerging pathogens in planetary health and lessons from comparative genome analyses of three Clostridia species” by Dr. Tanwar AS, Ms. Shruptha P, Ms. Jnana A, Dr. Brand A, Dr. Ballal M, Dr. Satyamoorthy K, and Dr. Murali TS. focusses on Clostridioides difficile (CD). CD is a major opportunistic pathogen responsible for severe gastrointestinal diseases such as pseudomembranous colitis, sepsis, organ dysfunction and several others. CD often co-occurs with traditionally less pathogenic Clostridia species, Clostridium butyricum (CB) and Clostridium tertium (CT). Current study attempts to explore the hypothesis that CB and CT might harbor virulence factors and antimicrobial resistance genes, potentially enhancing the severity of CD infections. Towards this, whole genome sequencing, genomic characterization of antimicrobial resistance and virulence along with culture based antimicrobial susceptibility tests, biofilm formation assays, cytotoxicity tests and toxin assays were performed.

KEY FINDINGS:

  • CB and CT, traditionally considered less pathogenic, harbored several virulence and AMR genes, suggesting potential roles as emerging pathogens.
  • Presence of phenotypic resistance towards ciprofloxacin in CB despite the absence of genomic evidence for the same hints toward the presence of “non inherited antibiotic resistance” and emphasized the need to explore antimicrobial resistance in the context of microbial interactions.
  • Bacterial hyaluronidase, nagK, which has been previously reported in Clostridium perfrigens was annotated in our CT strain. Presence of virulent hyaluronidases involved in toxin dispersal indicates potential pathogenic roles of gut commensals.
  • Study highlights the need for a more comprehensive approach to understanding and combating CD infections, considering the complex interactions within the gut microbiome.

METHODOLOGY:

Culture based characterization

  • Starch hydrolysis assay and motility test to identify CB, CD and CT
  • Minimum inhibitory concentration tests to assess antimicrobial susceptibility
  • Biofilm formation tests and in vitro cytotoxicity assays to estimate virulence
  • Transfection and T-cell factor reporter assay to assess antiproliferative activity of known Clostridia toxins A and B

Genomic characterization

  • Whole genome sequencing of CB, CD and CT (Ion Torrent PGM).
  • Genome assembly (reference-based assembly using SPAdes v3.13) followed by genome annotation and functional annotation
  • Comparative pangenome analysis
  • Genomic antimicrobial profiling
  • Genomic virulence profiling

MAJOR RESULTS:

  • Dual cultures of CD MALS003 and CT MALS001 showed significantly higher levels of biofilm production compared to monocultures while CB MALS002 and CT MALS001 dual cultures showed similar levels of biofilm production as their respective individual cultures.
  • The crude secretome of all three bacterial species showed significant cytotoxic effect at 24, 48 and 72h while only CD showed significant antiproliferative activity.
  • Relative contribution of protein families involved in ‘‘dormancy and sporulation’’

was higher in CB MALS002 (4.1%) compared to CD MALS003 (2.1%, twofold decrease) and CT MALS001 (1.3%, threefold decrease) which was also confirmed by the presence of higher number of sporulation genes in CB (48) followed by CT (47) and CD (32).

  • CD harbored the most toxin/virulence genes (54), followed by CT (14) and CB (13). Profile was maintained even in terms of antimicrobial resistance.

CONCLUSIONS:

  • Genomic surveillance of multiple species can provide insights into pathogen evolution and improve understanding of AMR development.
  • This research highlights the need for comprehensive approaches in studying infectious diseases, considering microbial interactions and genomic potential of co-occurring species.
  • The findings offer new avenues for genomic monitoring of emerging pathogens and may lead to better treatment strategies for antibiotic-resistant infections like CDI.

Citation to the base paper: Tanwar AS, Shruptha P, Jnana A, Brand A, Ballal M, Satyamoorthy K, Murali TS. 2023. Emerging pathogens in planetary health and lessons from comparative genome analyses of three Clostridia species. OMICS: A Journal of Integrative Biology 27, 247-259.

Publication Date

2023

Recommended Citation

Tanwar AS, Shruptha P, Jnana A, Brand A, Ballal M, Satyamoorthy K, Murali TS, " Emerging pathogens in planetary health and lessons from comparative genome analyses of three Clostridia species"(2023). OpenAccessarchive.

Publication Date

2023

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