Rapid slide coagglutination test for identifying and typing group B streptococci

Area of Science:

• Clinical microbiology
• Bacteriology
• Immunodiagnostics

Background:

• Accurate identification of Group B Streptococcus (GBS) is crucial for clinical management and epidemiological studies.
• Traditional methods like the Lancefield capillary precipitin test can be time-consuming and require specialized reagents.

Purpose of the Study:

• To evaluate a novel slide coagglutination test utilizing antibody-labeled reagent cells (ARC) for rapid and reliable identification and typing of GBS.
• To compare the performance of the coagglutination test with the standard Lancefield capillary precipitin test.

Main Methods:

• Staphylococcus aureus Cowan I strain was labeled with GBS grouping or typing antiserum to create ARC.
• ARC were used in slide coagglutination tests for GBS identification and typing directly from blood agar plates or acid extracts.
• A blind study was conducted comparing coagglutination results with the Lancefield test.

Main Results:

• The coagglutination grouping test correctly identified all 141 GBS strains, with no cross-reactivity from 148 non-GBS strains.
• The coagglutination typing test achieved 98.6% accuracy for GBS serotypes.
• Grouping and typing could be performed rapidly, with some typing completed within 5 minutes directly from plates.

Conclusions:

• The coagglutination grouping and typing tests provide a rapid, inexpensive, reliable, and easy-to-perform method for GBS identification and serotyping.
• This method offers a significant advantage over traditional techniques in terms of speed and simplicity.