Development and characterization of a Staphylococcus aureus nasal colonization model in mice
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Published on: January 17, 2014
K B Kiser1, J M Cantey-Kiser, J C Lee
1Channing Laboratory, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts 02115, USA.
Abstract:
Staphylococcus aureus nasal carriage is a risk factor for infection in humans, particularly in the hospital environment. Attenuation of carriage has proven effective in reducing the prevalence of infection in some high-risk groups. To study staphylococcal factors that influence nasal colonization, a mouse model of S. aureus nasal colonization was developed. Mice were inoculated intranasally with S. aureus Reynolds, and nasal carriage was evaluated by quantitating cultures of the nasal tissues from mice sacrificed at various time points after inoculation. The majority of mice inoculated with 10(8) CFU of S. aureus maintained nasal carriage for at least 20 days. Nasal colonization rates were similar for inbred (BALB/c and C57BL/6) and outbred (ICR) mice. Colonization was not affected by mouse passage of strain Reynolds. Lower inoculum doses (<10(7) CFU) resulted in reduced colonization after 7 days. However, mice given streptomycin in their drinking water developed long-term carriage of S. aureus, and they were colonized with inocula as low as 10(5) CFU. Nasal colonization was also established with two other S. aureus strains (one strain each of human and murine origins). S. aureus recovered from the nares of experimentally colonized mice expressed high levels of capsule, and the ability of a capsule-defective mutant to persist in the nares was reduced in comparison to that of the parent strain. This nasal colonization model should prove useful for studies of factors that mediate S. aureus colonization and for assessment of targets for antimicrobial intervention or vaccine development.
Insights
A new mouse model effectively simulates Staphylococcus aureus nasal carriage, a key risk factor for infections. This model aids in studying colonization factors and developing new antimicrobial interventions.
Area of Science:
- Microbiology
- Infectious Diseases
- Immunology
Background:
- Staphylococcus aureus nasal carriage is a significant risk factor for human infections, especially in hospital settings.
- Reducing S. aureus carriage can decrease infection prevalence in high-risk populations.
- Understanding factors influencing nasal colonization is crucial for developing effective interventions.
Purpose of the Study:
- To develop and validate a mouse model for studying Staphylococcus aureus nasal colonization.
- To investigate factors influencing the duration and success of S. aureus nasal carriage in mice.
Main Methods:
- Mice were intranasally inoculated with Staphylococcus aureus strain Reynolds.
- Nasal carriage was quantified by culturing nasal tissues at various time points post-inoculation.
- Colonization was assessed with different inoculum doses, mouse strains, and S. aureus strains, including a capsule-defective mutant.
Main Results:
- The majority of mice maintained S. aureus nasal carriage for at least 20 days with a high inoculum (10^8 CFU).
- Colonization rates were consistent across different inbred and outbred mouse strains.
- Streptomycin treatment enhanced long-term carriage, even with lower inocula (10^5 CFU).
- Capsule expression by S. aureus was associated with successful nasal persistence; capsule-defective mutants showed reduced colonization.
Conclusions:
- The developed mouse model reliably mimics Staphylococcus aureus nasal colonization.
- This model is valuable for investigating S. aureus colonization mechanisms.
- The model can be used to evaluate potential antimicrobial targets and vaccine strategies.
