Swimming pool granuloma is caused by –
**Core Concept**
Swimming pool granuloma is a type of cutaneous granuloma caused by an infection. The underlying principle being tested is the association between a specific bacterium and its clinical manifestation.
**Why the Correct Answer is Right**
Swimming pool granuloma is caused by Mycobacterium marinum, a waterborne pathogen that typically infects people through minor skin injuries while handling aquarium fish or swimming in contaminated water. The bacteria enter the body through the wound and cause an immune response, leading to the formation of granulomas. Mycobacterium marinum is a non-tuberculous mycobacterium that belongs to the same genus as Mycobacterium tuberculosis, but it is less virulent and typically causes localized infections.
**Why Each Wrong Option is Incorrect**
* **Option A:** Pseudomonas aeruginosa is a common cause of opportunistic infections, particularly in immunocompromised patients, but it is not associated with swimming pool granuloma.
* **Option B:** Staphylococcus aureus is a common cause of skin infections, but it is not the causative agent of swimming pool granuloma.
* **Option C:** Escherichia coli is a common cause of urinary tract infections and gastrointestinal infections, but it is not associated with swimming pool granuloma.
**Clinical Pearl / High-Yield Fact**
Mycobacterium marinum infections can also occur through contact with contaminated soil or water, highlighting the importance of proper hand hygiene and wound care when handling aquarium fish or swimming in public pools.
**Correct Answer: A. Mycobacterium marinum**