5 year old child with pseudomembrane in throat, fever, sore throat, the organism causing is
**Core Concept**
The question describes a clinical presentation of a 5-year-old child with a pseudomembrane in the throat, fever, and sore throat. This presentation is suggestive of a bacterial infection, specifically diphtheria, caused by Corynebacterium diphtheriae.
**Why the Correct Answer is Right**
The correct answer is due to the presence of a pseudomembrane in the throat, which is a hallmark of diphtheria. This pseudomembrane is formed by the bacterial toxin that causes tissue damage and necrosis. The toxin, diphtheria toxin, inhibits protein synthesis by cleaving the elongation factor 2 (EF-2), leading to cell death and the formation of the pseudomembrane. The toxin is produced by the bacterium Corynebacterium diphtheriae.
**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because the organism causing the described clinical presentation is not Streptococcus pyogenes, which typically causes strep throat, characterized by a bright red throat and swollen lymph nodes, but not a pseudomembrane.
* **Option B:** This option is incorrect because Haemophilus influenzae type b is a cause of epiglottitis, which typically presents with severe respiratory distress, stridor, and a droopy soft palate, but not a pseudomembrane in the throat.
* **Option C:** This option is incorrect because Staphylococcus aureus can cause a range of infections, including skin and soft tissue infections, but it is not typically associated with a pseudomembrane in the throat.
* **Option D:** This option is incorrect because Escherichia coli is a gram-negative bacterium that can cause urinary tract infections, but it is not associated with a pseudomembrane in the throat.
**Clinical Pearl / High-Yield Fact**
Diphtheria is a vaccine-preventable disease, and the toxin is responsible for the clinical manifestations. Remember the word "diphtheria" to associate it with the toxin that causes tissue damage and necrosis.
**Correct Answer:** C. Corynebacterium diphtheriae.