Elek&;s gel precipitation test is for
Elek's gel precipitation test: a rectangular strip of filter paper impregnated with diphtheria antitoxin is placed on the surface of a 20% normal horse serum agar in a Petri dish while the medium is still fluid. When the agar has set, the surface is dried and narrow streaks of strains are made at right angles to filter paper strip. A positive and negative control should be put up. The plate is incubated at 37degC for 24-48 hours. The toxin produced by the bacterial growth will diffuse in agar and where it meets the antitoxin at optimum concentration, will produce a line of precipitation. The presence of such arrow headlines of a precipitate indicates the strain is toxigenic. No precipitate is formed in the case of non-toxigenic strains. Reference: Textbook of Microbiology; Anathanarayan and panicker's; 10th edition; Page no: 243
Gonococcus
Diphtheria
Hemophilus influenza
Anthrax
Bacteriology