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Antiserum agar method for identification of Smith type exopolysaccharides in clinical isolates of Staphylococcus
Abstract:
We used an antiserum agar method to identify clinical Staphylococcus aureus strains producing an exopolysaccharide antigenically identical to the S. aureus Smith diffuse strain. S. aureus blood isolates were obtained from 137 patients, and three additional isolates were obtained from bone debridement. The 140 patients were clinically divided into the following groups: endocarditis (7 patients); pneumonia, empyema, or both (33 patients); intravascular device (34 patients); superficial or wound infection or both (35 patients); deep tissue infections (18 patients); and 6, unknown bacteremias (13 patients). Ninety (64.3%) of the total 140 S. aureus isolates were found to produce precipitin halos on the antiserum agar. The percentage was greatest in the isolates from the endocarditis group (100%) and least in deep tissue infections (55.5%). The presence of clinical S. aureus strains producing exopolysaccharides antigenically identical to the Smith diffuse strain exopolysaccharide appears to be a common phenomenon.
Insights
Most clinical Staphylococcus aureus strains produce exopolysaccharides similar to the Smith diffuse strain. This finding was common across various patient infection types, especially endocarditis.
Area of Science:
- Microbiology
- Immunology
Background:
- Staphylococcus aureus is a significant human pathogen.
- The Smith diffuse strain of S. aureus produces a characteristic exopolysaccharide.
- The role of this exopolysaccharide in clinical infections is not fully understood.
Purpose of the Study:
- To identify clinical Staphylococcus aureus strains producing exopolysaccharides antigenically identical to the S. aureus Smith diffuse strain.
- To determine the prevalence of these strains across different types of S. aureus infections.
Main Methods:
- Antiserum agar method was employed for identification.
- Clinical isolates of S. aureus were collected from 140 patients with various infections.
- Isolates were tested for precipitin halos on antiserum agar.
Main Results:
- Ninety (64.3%) of 140 S. aureus isolates produced precipitin halos.
- The highest percentage (100%) was observed in isolates from endocarditis patients.
- The lowest percentage (55.5%) was found in deep tissue infections.
Conclusions:
- Clinical S. aureus strains producing exopolysaccharides antigenically identical to the Smith diffuse strain are common.
- The prevalence varies with the type of infection, being highest in endocarditis.