An 11-year-old child presented with sore throat since 3 days, which medium is used to culture the throat swab
## **Core Concept**
The question tests knowledge of microbiological culturing techniques, specifically for diagnosing pharyngeal infections. The most common cause of bacterial sore throat is *Streptococcus pyogenes*, a Group A beta-hemolytic streptococcus (GABHS). The choice of culture medium is critical for isolating this pathogen.
## **Why the Correct Answer is Right**
The correct answer, **Blood Agar**, is the medium used to culture throat swabs, particularly for suspected *Streptococcus pyogenes* infections. Blood agar supports the growth of streptococci and allows for the observation of hemolysis patterns. *Streptococcus pyogenes* exhibits beta-hemolysis on blood agar, which appears as a clear zone around colonies due to complete red blood cell lysis. This characteristic helps in identifying the pathogen.
## **Why Each Wrong Option is Incorrect**
- **Option A: MacConkey Agar** is selective for Gram-negative bacteria and is not used for culturing streptococci from throat swabs.
- **Option B: Sabouraud Dextrose Agar** is used for fungal cultures, not for bacterial throat infections.
- **Option D: Chocolate Agar** is enriched with factors (like X and V) to support the growth of fastidious organisms like *Haemophilus* and *Neisseria* species, not typically for streptococcal throat infections.
## **Clinical Pearl / High-Yield Fact**
A key clinical pearl is that a rapid antigen detection test (RADT) or throat culture on blood agar are diagnostic tools for streptococcal pharyngitis. The choice of blood agar for culture is crucial for confirming the diagnosis and guiding antibiotic therapy.
## **Correct Answer:** . Blood Agar