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Virulence of genus Staphylococcus. III. Studies on the pathogenicity to mice
Abstract:
Six representative strains of staphylococci were selected on the basis of DNase activity and inoculated into the mice to study the correlation of the presence of this enzyme to the virulence of the staphylococci. Two strains of staphylococci among them produced DNase but not the free coagulase, and one of these two strains had an obvious virulence against the mice. The results of experiments suggest that there are at least certain strains which may be designated as Staphylococcus aureus among these DNase-producing staphylococci producing no free coagulase. This is an additional evidence that this enzyme activity should be adopted as a criterion to distinguish from the other S. aureus which has lost the free coagulase activity. In this sense, the staphylococci producing neither free coagulase nor DNase are after all Staphylococcus epidermidis, regardless of their ability to ferment mannitol or not.
Insights
DNase activity in staphylococci correlates with virulence. Some DNase-positive strains lacking free coagulase may be Staphylococcus aureus, suggesting DNase as a key diagnostic marker.
Area of Science:
- Microbiology
- Bacteriology
- Infectious Diseases
Background:
- Staphylococci are a diverse group of bacteria.
- Virulence factors in Staphylococcus species are crucial for pathogenicity.
- Distinguishing between pathogenic and non-pathogenic strains is important for clinical management.
Purpose of the Study:
- To investigate the correlation between DNase activity and virulence in staphylococci.
- To evaluate DNase as a potential diagnostic marker for Staphylococcus aureus.
- To differentiate Staphylococcus aureus strains lacking free coagulase activity.
Main Methods:
- Selection of six representative staphylococci strains based on DNase activity.
- Inoculation of selected strains into mice to assess virulence.
- Enzyme activity assays (DNase and free coagulase).
Main Results:
- One of two DNase-positive, free coagulase-negative strains exhibited significant mouse virulence.
- These findings suggest certain DNase-producing strains lacking free coagulase are Staphylococcus aureus.
- Staphylococci lacking both free coagulase and DNase were identified as Staphylococcus epidermidis.
Conclusions:
- DNase activity can serve as a criterion to identify Staphylococcus aureus strains.
- This enzyme activity helps distinguish virulent strains, even those lacking free coagulase.
- The study supports the use of DNase testing in staphylococcal identification and virulence assessment.