In a completely and adequately immunized child against diphtheria, the throat swab was collected. It showed the presence of C.diphtheriae organisms on Albert staining. These organisms can have one of the following properties on further processing:
**Core Concept**
The question revolves around the properties of *Corynebacterium diphtheriae*, the bacterium responsible for diphtheria, in an immunized child. Immunization against diphtheria involves the use of *diphtheria toxoid*, which induces immunity against the toxin produced by *C. diphtheriae*, not against the bacterium itself.
**Why the Correct Answer is Right**
Since the child is immunized against the toxin, not the bacterium, the presence of *C. diphtheriae* in the throat swab is possible. The key property to look for in this context is the ability of the bacteria to produce toxin, which is determined by the presence of the *tox gene*. However, without specific options provided, we focus on the principle that immunization status affects toxin response, not bacterial colonization.
**Why Each Wrong Option is Incorrect**
**Option A:** Without the specific option text, we cannot directly address why it is incorrect, but generally, options that suggest immunity prevents bacterial colonization would be incorrect.
**Option B:** Similarly, without specifics, but options implying that immunization directly affects the bacterium's viability or presence would be misleading.
**Option C:** This might suggest a property unrelated to toxin production or immunity, which would not be directly relevant to the scenario described.
**Option D:** Could potentially be about the lack of disease manifestation due to immunity, which, while true, does not directly relate to the bacterial properties being queried.
**Clinical Pearl / High-Yield Fact**
A crucial point to remember is that vaccination against diphtheria protects against the toxin's effects, not against colonization by *C. diphtheriae*. Thus, an immunized individual can still carry and transmit the bacteria.
**Correct Answer:** Correct Answer: D. Non-toxigenic.