Fildes technique is used for the culture of?
A. Clostridium perfringens
B. Clostridium tetani
C. Clostridium botulinum
D. Clostridium difficile
Correct answer : B. Clostridium tetani
Clostridium tetani - tennis racketTennis racket appearance of Clostridium tetani
Clostridium tetani grows on ordinary media.
Growth can be improved by blood and serum.
Because of marked tendency to swarm over the surface of the agar, surface colonies are difficult to obtain.
After incubating anaerobically for 24 hours, if the water of condensation at the bottom of a slope of nutrient agar is inoculated with a mixed cell culture, subcultures from the top of the tube will yield a pure growth of tetanus bacillus.
This is called Fildes technique.
Ref: Ananthanarayan and Paniker’s Textbook of Microbiology, 9th edition, p259, 260
Image credits: Centers for Disease Control and Prevention’s Public Health Image Library. http://phil.cdc.gov/phil/details.asp?pid=6372