Microbiology Practice Exam

What is a common complication that can develop from untreated strep throat?

1. Scarlet fever

2. Rheumatic fever

3. Chronic sinusitis

4. Mononucleosis

The correct answer is: Rheumatic fever

Rheumatic fever is a significant complication that can arise from untreated strep throat, specifically caused by the bacterium Streptococcus pyogenes. This condition is an autoimmune response that occurs when the body’s immune system mistakenly attacks its own tissues following a strep infection. If strep throat is not effectively treated, particularly in children, the inflammation can lead to serious issues affecting the heart, joints, skin, and brain. The mechanism involves the body developing antibodies to the streptococcal bacteria, which can cross-react with similar protein structures in the heart and other tissues, leading to inflammation and potential damage. This can eventually manifest as rheumatic heart disease, presenting further health complications such as heart valve issues. Regarding the other options, while scarlet fever is indeed related to strep throat and can arise if the infection is left untreated, it is not considered a complication in the same severe, long-term way as rheumatic fever. Chronic sinusitis is also not a direct complication of strep throat, while mononucleosis is caused by the Epstein-Barr virus, which is unrelated to streptococcal infections. Therefore, rheumatic fever is the most serious and direct complication associated with untreated strep throat.