For early diagnosis of corynebacteria diphtheria medium used is
**Core Concept**
Corynebacteria diphtheria, caused by Corynebacterium diphtheriae, is a bacterial infection that requires early diagnosis for effective management. The medium used for early diagnosis of corynebacteria diphtheria is a selective medium that allows the growth of the pathogen while inhibiting other contaminants.
**Why the Correct Answer is Right**
The medium used for early diagnosis of corynebacteria diphtheria is Löwenstein-Jensen (LJ) medium, which is a selective medium that contains iron salts and malachite green. The iron salts inhibit the growth of other bacteria, while malachite green inhibits the growth of fungi. Corynebacterium diphtheriae grows well on LJ medium due to its ability to reduce the iron salts, which is a key virulence factor for the bacterium. The growth of C. diphtheriae on LJ medium is typically characterized by a rough, granular appearance and a blue-green pigment due to the reduction of malachite green.
**Why Each Wrong Option is Incorrect**
* **Option A:** Blood agar is not a selective medium for corynebacteria diphtheria and would not inhibit the growth of other contaminants.
* **Option B:** MacConkey agar is a selective medium for gram-negative bacteria, particularly Enterobacteriaceae, and would not be suitable for the isolation of C. diphtheriae.
* **Option D:** Chocolate agar is a non-selective medium that is used for the isolation of fastidious bacteria, such as Haemophilus influenzae, but would not inhibit the growth of other contaminants.
**Clinical Pearl / High-Yield Fact**
It's essential to remember that Löwenstein-Jensen medium is a selective medium that requires careful handling and incubation to prevent contamination. A characteristic blue-green pigment on the surface of the agar is a key clue for the identification of Corynebacterium diphtheriae.
**Correct Answer: C. Löwenstein-Jensen medium**