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Subcutaneous Infection of Methicillin Resistant Staphylococcus Aureus MRSA
Published on: February 9, 2011
Monitoring Staphylococcus aureus nasal colonization murine model using a bioluminescent methicillin-resistant S.
Juliana G da Silva1, Juliana Pc Boechat1, Bruno Dj Silva1
1FIOCRUZ, Instituto de Tecnologia em Imunobiológicos, Rio de Janeiro, Brazil.
Abstract:
Staphylococcus aureus nasal carriage is considered a risk factor for infections, and the development of nasal decolonization strategies is highly relevant. Despite they are not naturally colonized by Staphylococcus, mice are a good model for S. aureus nasal colonization. Murine models are easy to manipulate, and inter-laboratory reproducibility makes them suitable for nasal colonization studies. Strategies using bioluminescent bacteria allow for the monitoring of infection over time without the need to sacrifice animals for bacterial quantification. In this study, we evaluated S. aureus nasal colonization in three mouse strains (BALB/c, C57BL/6, and Swiss Webster) using a bioluminescent strain (SAP231). In vitro, a visible Bioluminescent Signal Emission (BLSE) was observed until 106 bacteria and detected by IVIS® imaging system up to 104 cells. Animals were inoculated with one or two doses of approximately 109 colony-forming units (CFU) of SAP231. Swiss Webster mice showed the longest colonization time, with some animals presenting BLSE for up to 140 h. In addition, BLSE was higher in this strain. BALB/c and C57BL/6 strains showed consistent BLSE results for 48 h. BLSE intensity was higher in Swiss Webster inoculated with both doses. Three different positions for image capture were evaluated, with better results for the lateral and ventrodorsal positions. After the loss of BLSE, bacterial quantification was performed, and Swiss Webster mice presented more bacteria in the nasal cavity (approximately 105 CFU) than the other strains. Our results demonstrate that bioluminescent S. aureus allow monitoring of nasal colonization and estimation of the bacterial burden present in live animals until 48 h.
Insights
Bioluminescent Staphylococcus aureus in mice allows for real-time nasal colonization monitoring. Swiss Webster mice show prolonged colonization, aiding decolonization strategy development.
Area of Science:
- Microbiology
- Infectious Diseases
- Animal Models
Background:
- Staphylococcus aureus nasal carriage is a significant infection risk factor.
- Developing effective nasal decolonization strategies is crucial.
- Murine models offer a reproducible platform for studying S. aureus nasal colonization.
Purpose of the Study:
- To evaluate Staphylococcus aureus nasal colonization in three mouse strains using bioluminescence.
- To assess the efficacy of bioluminescent imaging for monitoring colonization over time.
- To compare colonization dynamics and bacterial burden across different mouse strains.
Main Methods:
- Utilized a bioluminescent Staphylococcus aureus strain (SAP231) for inoculation.
- Administered one or two doses of approximately 10^9 colony-forming units (CFU) to BALB/c, C57BL/6, and Swiss Webster mice.
- Monitored nasal colonization using in vivo bioluminescent signal emission (BLSE) imaging and subsequent bacterial quantification.
Main Results:
- Swiss Webster mice exhibited the longest colonization duration (up to 140 hours) and highest BLSE intensity.
- BALB/c and C57BL/6 strains showed consistent BLSE for 48 hours.
- Post-BLSE loss quantification revealed higher bacterial loads in Swiss Webster mice (approx. 10^5 CFU).
Conclusions:
- Bioluminescent Staphylococcus aureus enables non-invasive monitoring of nasal colonization in live animals.
- Swiss Webster mice are a suitable model for prolonged S. aureus nasal colonization studies.
- BLSE imaging provides valuable insights into bacterial burden and colonization dynamics.
