Related Experiment Video
Updated: Mar 20, 2026
Development and Assessment of Intracellular Infection Models for Staphylococcus aureus
Published on: January 17, 2025
MRI Based Localisation and Quantification of Abscesses following Experimental S. aureus Intravenous Challenge:
Elizabeth R Allen1, Pauline van Diemen1, Yuko Yamaguchi1
1Jenner Institute, Centre for Cellular and Molecular Physiology, University of Oxford, Oxford, United Kingdom.
Purpose:
To develop and validate a sensitive and specific method of abscess enumeration and quantification in a preclinical model of Staphylococcus aureus infection.
Methods:
S. aureus infected murine kidneys were fixed in paraformaldehyde, impregnated with gadolinium, and embedded in agar blocks, which were subjected to 3D magnetic resonance microscopy on a 9.4T MRI scanner. Image analysis techniques were developed, which could identify and quantify abscesses. The result of this imaging was compared with histological examination. The impact of a S. aureus Sortase A vaccination regime was assessed using the technique.
Results:
Up to 32 murine kidneys could be imaged in a single MRI run, yielding images with voxels of about 25 μm3. S. aureus abscesses could be readily identified in blinded analyses of the kidneys after 3 days of infection, with low inter-observer variability. Comparison with histological sections shows a striking correlation between the two techniques: all presumptive abscesses identified by MRI were confirmed histologically, and histology identified no abscesses not evident on MRI. In view of this, simulations were performed assuming that both MRI reconstruction, and histology examining all sections of the tissue, were fully sensitive and specific at abscess detection. This simulation showed that MRI provided more sensitive and precise estimates of abscess numbers and volume than histology, unless at least 5 histological sections are taken through the long axis of the kidney. We used the MRI technique described to investigate the impact of a S. aureus Sortase A vaccine.
Conclusion:
Post mortem MRI scanning of large batches of fixed organs has application in the preclinical assessment of S. aureus vaccines.
Insights
Magnetic resonance microscopy offers a sensitive and specific method for quantifying Staphylococcus aureus abscesses in preclinical kidney infection models. This technique aids in evaluating vaccine efficacy, outperforming traditional histology in accuracy.
Area of Science:
- Medical Imaging
- Infectious Disease Research
- Preclinical Models
Background:
- Staphylococcus aureus infections frequently lead to abscess formation.
- Accurate quantification of abscesses is crucial for evaluating treatment efficacy and vaccine development.
- Current methods like histology can be labor-intensive and may miss smaller abscesses.
Purpose of the Study:
- To develop and validate a sensitive and specific method for abscess enumeration and quantification.
- To utilize 3D magnetic resonance microscopy (MRI) in a preclinical model of Staphylococcus aureus kidney infection.
- To compare the efficacy of MRI with traditional histological examination for abscess detection.
Main Methods:
- Murine kidneys infected with S. aureus were fixed, impregnated with gadolinium, and embedded in agar.
- 3D MRI was performed on a 9.4T scanner, followed by development of image analysis techniques for abscess identification and quantification.
- Results were compared with histological examination, and the impact of a S. aureus Sortase A vaccine was assessed.
Main Results:
- Up to 32 kidneys were imaged per run with 25 μm3 voxels.
- S. aureus abscesses were readily identified with low inter-observer variability after 3 days of infection.
- MRI showed a striking correlation with histology, providing more sensitive and precise estimates of abscess numbers and volume than histology.
Conclusions:
- Post-mortem MRI scanning of fixed organs is a valuable tool for preclinical assessment of S. aureus vaccines.
- The developed MRI technique offers a sensitive, specific, and efficient method for abscess quantification.
- This approach has significant implications for accelerating vaccine development and drug discovery.
