Home › Cell Biology › Capsular Serotyping of Streptococcus pneumoniae Using the Quellung Reaction
Cell Biology JoVE (Open Access) Citable · DOI

Capsular Serotyping of Streptococcus pneumoniae Using the Quellung Reaction

DOI: 10.3791/51208-v
What you'll learn
  • ✓ Prepare bacterial cell suspensions correctly for Quellung serotyping
  • ✓ Perform the Quellung reaction using pneumococcal antisera and microscopy
  • ✓ Interpret positive and negative Quellung reaction results
Protocol

The Quellung reaction is the gold standard technique for serotyping Streptococcus pneumoniae. This technique utilizes a microscope and specific pneumococcal antisera and is commonly used in reference and research laboratories worldwide.

Difficulty
intermediate
Total time
~30–45 minutes per sample
Biosafety
BSL-2

Steps

1
Prepare cell suspension for serotyping

Create a bacterial cell suspension from Streptococcus pneumoniae culture using appropriate media or saline solution to achieve optimal concentration for microscopic examination.

▶ 01:12
2
Perform Quellung reaction with antisera

Apply specific pneumococcal antisera to the cell suspension on a microscope slide and incubate to allow serotype-specific capsular swelling to occur.

▶ 02:29
3
Examine and interpret reaction outcomes

Observe slides under microscopy to identify positive Quellung reactions (visible capsular swelling around bacteria) versus negative controls lacking capsular changes.

▶ 03:03
💬 Comments coming soon