SCHWÖRM AGAR

For Salmonella H‑phase detection.

A Salmonella bacterium expresses normally only one H antigen at a time and in the Salmonella culture usually only one of the H phases is dominating. This dominating phase is called the first phase and can be determined by agglutination with H antisera. The culture should be grown on a semisolid agar as Schwörm agar.

The second phase is determined by adding phase inversion antisera against the identified first phase to the Schwörm agar. This procedure allows the bacteria to express the second H phase antigen and swarm.