## **Core Concept**
Group A β-hemolytic streptococcal (GABHS) infections, caused by *Streptococcus pyogenes*, are a common cause of pharyngitis. A well-known complication of GABHS infections is the development of autoimmune sequelae due to the similarity between certain streptococcal antigens and human tissues.

## **Why the Correct Answer is Right**
The correct answer, , is right because rheumatic fever is a recognized complication of untreated or inadequately treated GABHS infections. This condition is an autoimmune inflammatory process that can affect the heart, joints, skin, and brain. The pathogenesis involves molecular mimicry, where antibodies against streptococcal antigens cross-react with similar antigens in human tissues, leading to inflammation and damage.

## **Why Each Wrong Option is Incorrect**
* **Option A:** is incorrect because, while glomerulonephritis is indeed a complication of GABHS infections, it is more commonly associated with skin infections rather than pharyngitis. It is also known as post-streptococcal glomerulonephritis (PSGN).
* **Option B:** is incorrect because toxic shock syndrome can be caused by various bacteria, including *Staphylococcus aureus* and *Streptococcus pyogenes*. However, it is not specifically a sequela of GABHS pharyngitis but rather an acute condition caused by bacterial toxins.
* **Option C:** is incorrect because, although *Streptococcus pyogenes* can cause necrotizing fasciitis, this condition is a severe and acute infection of the soft tissues, not a sequela of pharyngitis.

## **Clinical Pearl / High-Yield Fact**
A key point to remember is that rheumatic fever can be prevented by treating GABHS pharyngitis promptly with antibiotics, highlighting the importance of early diagnosis and treatment. The Jones criteria are used for the diagnosis of rheumatic fever.

## **Correct Answer:** . Rheumatic fever