KROK 1 2011 – Question 44 · KROK (Medicine) · Microbiology, Virology, and Immunology
In order to determine toxigenicity of diphtheria bacilli a strip of filter paper impregnated with antitoxic diphtherial serum was put on the dense nutrient medium. There were also inoculated a microbial culture under examination and a strain that is known to be toxigenic. If the microbial culture under examination produces exotoxin, this will result in formation of:
- A. Zones of lecithovitellinous activity
- B. Haemolysis zones
- C. Zones of diffuse opacification
- D. Precipitin lines
- E. Precipitin ring
Hint
Consider what the toxin and the antitoxin serum do when they diffuse towards each other through agar, and what the visible sign of their meeting looks like.
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