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Updated: May 18, 2026
Automated Separation of C. elegans Variably Colonized by a Bacterial Pathogen
Published on: March 21, 2014
Effects of sequential infections of Caenorhabditis elegans with Staphylococcus aureus and Proteus mirabilis
Gnanasekaran JebaMercy1, Krishnaswamy Balamurugan
1Department of Biotechnology, Alagappa University, Karaikudi-630 003, India.
Abstract:
Caenorhabditis elegans can be used to study the dynamics of polymicrobial infections, specifically those between Gram-positive and Gram-negative bacteria. With C. elegans, Proteus mirabilis acts as an opportunistic pathogen and does not kill this host. Hence, in the present study, C. elegans was immunochallenged by pre-infecting it with the pathogen Staphylococcus aureus in order to study the subsequent effect of P. mirabilis on the host. It was found that 12 hrs of S. aureus and 80 hrs of subsequent P. mirabilis infection significantly reduced the life span of exposed C. elegans by 80%. However, preinfection with S. aureus for 8 and 4 hrs reduced the life span of C. elegans by only 60 and 30%, respectively. Further, there was greater production of reactive oxygen species in the sequentially infected samples than in the S. aureus and P. mirabilis controls. Real time PCR analysis indicated regulation of candidate immune regulatory genes, lysozyme (lys-7), CUB-like proteins (F08G5.6), neuropeptide-like factors (nlp-29), transcription factors of mitogen-activated protein kinase (ATF-7) and daf-2-daf-16 (daf-16), insulin-like signaling pathways and C-type lectin (clec-60 and clec-87) family members during S. aureus and subsequent P. mirabilis-mediated infections, indicating possible roles of, and contributions by, the above factors during host immune responses against these sequential infections. The present findings demonstrate that S. aureus infections increase the vulnerability of the C. elegans host by subverting its immune system, which then permits the opportunistic pathogen P. mirabilis to be pathogenic to this host.
Insights
Pre-infection with Staphylococcus aureus compromises the immune system of Caenorhabditis elegans, making it vulnerable to subsequent opportunistic infections by Proteus mirabilis, significantly reducing lifespan.
Area of Science:
- Microbiology
- Immunology
- Infectious Disease Dynamics
Background:
- Caenorhabditis elegans is a model organism for studying polymicrobial infections.
- Proteus mirabilis is an opportunistic pathogen that does not typically kill C. elegans.
- Staphylococcus aureus can act as a primary pathogen.
Purpose of the Study:
- To investigate the effect of sequential infections of Staphylococcus aureus followed by Proteus mirabilis on C. elegans lifespan.
- To explore the host immune response mechanisms involved in these polymicrobial infections.
Main Methods:
- C. elegans were sequentially infected with S. aureus and P. mirabilis.
- Lifespan assays were conducted to measure host survival.
- Reactive oxygen species production was quantified.
- Gene expression analysis using Real-Time PCR was performed on immune regulatory genes.
Main Results:
- Sequential infection with S. aureus and P. mirabilis significantly reduced C. elegans lifespan, with the reduction correlating with the duration of S. aureus pre-infection.
- Increased reactive oxygen species production was observed in sequentially infected worms compared to single-pathogen controls.
- Real-Time PCR revealed differential regulation of immune genes, including lys-7, F08G5.6, nlp-29, ATF-7, daf-16, clec-60, and clec-87.
Conclusions:
- Staphylococcus aureus pre-infection enhances the pathogenicity of the opportunistic pathogen Proteus mirabilis in C. elegans.
- The host immune system is subverted by S. aureus, increasing vulnerability to subsequent infections.
- The study highlights the complex interplay of immune responses and gene regulation during sequential polymicrobial infections.
