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Published on: April 2, 2013
Influence of sequential cultivation on virulence of Legionella pneumophila and Staphylococcus aureus
M Nagl1, R Starlinger, F Tiefenbrunner
1Institut für Hygiene und Sozialmedizin, Leopold-Franzens-Universität Innsbruck, Austria.
Abstract:
Virulence of Legionella pneumophila strain Monza 3 and Staphylococcus aureus strain Smith diffuse was investigated after sequential cultures on nutrient media. L. pneumophila lost its ability to multiply within Acanthamoeba polyphaga after 50 passages on Legionella selective agar, while S. aureus maintained its pathogenicity in the mouse peritonitis model after 100 sequential cultures on tryptic soy agar. These results demonstrate high preservation of virulence in staphylococci in contrast to legionellae. Differentiation of virulent and avirulent phenotypes of legionellae by the protozoal model may be helpful for detecting sources of infection in water hygiene.
Insights
Legionella pneumophila lost virulence after repeated culturing, unlike Staphylococcus aureus. This finding aids in differentiating virulent Legionella strains for water hygiene surveillance.
Area of Science:
- Microbiology
- Pathogen Virulence Studies
- Bacterial Pathogenesis
Background:
- Legionella pneumophila and Staphylococcus aureus are significant human pathogens.
- Understanding pathogen virulence preservation during laboratory culturing is crucial for accurate research and clinical relevance.
- Sequential culturing can alter bacterial virulence, impacting experimental outcomes.
Purpose of the Study:
- To compare the preservation of virulence in Legionella pneumophila and Staphylococcus aureus after repeated subculturing on nutrient media.
- To assess the impact of laboratory cultivation on the pathogenicity of these two distinct bacterial species.
Main Methods:
- Sequential culturing of Legionella pneumophila strain Monza 3 on Legionella selective agar for 50 passages.
- Sequential culturing of Staphylococcus aureus strain Smith diffuse on tryptic soy agar for 100 passages.
- Assessing L. pneumophila virulence by its ability to multiply within Acanthamoeba polyphaga.
- Assessing S. aureus pathogenicity using a mouse peritonitis model.
Main Results:
- Legionella pneumophila lost its intracellular multiplication ability in Acanthamoeba polyphaga after 50 passages.
- Staphylococcus aureus maintained its pathogenicity in the mouse peritonitis model after 100 passages.
- Demonstrated high preservation of virulence in S. aureus compared to L. pneumophila.
Conclusions:
- Staphylococci exhibit significantly higher virulence preservation during sequential culturing than legionellae.
- The Acanthamoeba protozoal model can differentiate virulent and avirulent Legionella phenotypes.
- This differentiation method may assist in identifying infection sources in water hygiene investigations.
