Dark ground microscopy is used for
Treponema pallidum immobilization (TPI) test Serum of patient with complement and T. pallidum are maintained in a complex medium anaerobically If the antibodies are present, the Treponemes are immobilized when examined under dark ground illumination.
TPI
Kahn's test
FTA-ABS
VDRL
General Microbiology Pa 1 (History, Microscopy, Stains and Structure and Physiology of Bacteria)