Rosh Pediatrics Practice Exam

In a 17-year-old girl with a positive tuberculosis test and a nodule on her finger, what is the likely cause of her exposure?

1. ACat scratch

2. BExposure of traumatized skin to aquarium water

3. CInhalation of airborne particles

4. DSand fly bite

The correct answer is: BExposure of traumatized skin to aquarium water

The situation presented involves a 17-year-old girl who has a positive tuberculosis test and a nodule on her finger. The presence of a nodule may suggest a specific type of exposure that leads to a localized infection or reaction, especially when considering tuberculosis, which is caused by Mycobacterium tuberculosis. In this context, exposure to aquarium water could involve mycobacterial species, specifically from water associated with contaminated aquarium environments. Mycobacterium marinum, which is often linked to aquarium water and can cause skin infections, typically manifests as a localized nodule, particularly on areas of the skin that may have been traumatized or have minor injuries. This scenario aligns well with the notion that the girl has been in contact with infected or contaminated water, causing a localized reaction at the site of exposure, hence the nodule on her finger. Understanding that tuberculosis is primarily transmitted through airborne routes emphasizes the potential for distinct cutaneous manifestations in specific scenarios, such as exposure through skin. The other options aren't as pertinent due to lack of direct correlation with tuberculosis or the skin nodule. For instance, cat scratch fever, while it can cause skin nodules, does not involve tuberculosis. Inhalation of airborne particles relates to respiratory transmission of tuberculosis but