Related Experiment Videos
Problems with rapid agglutination methods for identification of Staphylococcus aureus when Staphylococcus
D B Gregson1, D E Low, M Skulnick
1Department of Microbiology, Mount Sinai Hospital, University of Toronto, Ontario, Canada.
Journal of Clinical Microbiology
|July 1, 1988
Summary
Rapid agglutination tests for identifying Staphylococcus aureus can be unreliable. Staphylococcus saprophyticus frequently causes false positives and uninterpretable results, necessitating confirmatory testing for accurate identification.
Area of Science:
- Clinical Microbiology
- Bacteriology
- Diagnostic Testing
Background:
- Accurate identification of Staphylococcus aureus is crucial for clinical diagnosis and treatment.
- Rapid agglutination tests offer a quick method for presumptive identification of S. aureus.
- Coagulase-negative staphylococci, particularly S. saprophyticus, can be misidentified by these rapid tests.
Purpose of the Study:
- To evaluate the performance of six rapid agglutination tests in identifying Staphylococcus aureus.
- To assess the accuracy of these tests when encountering Staphylococcus saprophyticus and other coagulase-negative staphylococci.
Main Methods:
- Six different rapid agglutination tests were assessed.
- A panel of 192 staphylococcal strains was used, including 62 S. aureus, 63 S. saprophyticus, and 67 other coagulase-negative staphylococci.
- Test results were analyzed for accuracy, false positives, and uninterpretable reactions.
Main Results:
- Staphylococcus saprophyticus was the primary cause of inaccurate results, accounting for 19 of 26 false-positive outcomes.
- S. saprophyticus also led to 20 uninterpretable reactions across the evaluated tests.
- The presence of S. saprophyticus significantly impacted the specificity and reliability of rapid agglutination tests for S. aureus.
Conclusions:
- Rapid agglutination tests show limitations in accurately identifying Staphylococcus aureus, especially in the presence of Staphylococcus saprophyticus.
- Urinary staphylococcal isolates testing positive via rapid agglutination may require additional confirmatory methods.
- Further investigation into confirmatory testing strategies is recommended to ensure precise identification of S. aureus and differentiate it from S. saprophyticus.