American Board of Internal Medicine (ABIM) Certification Practice Exam

Which organism is associated with skin infections in patients who frequent nail salons using contaminated footbaths?

1. Staphylococcus aureus

2. Mycobacterium fortuitum

3. Escherichia coli

4. Clostridium difficile

The correct answer is: Mycobacterium fortuitum

Mycobacterium fortuitum is a type of non-tuberculous mycobacterium that is commonly associated with skin infections, particularly in individuals who have undergone procedures involving water, such as those found in contaminated footbaths at nail salons. The organism is part of a group of rapidly growing mycobacteria that can be present in environmental sources, including water systems. When footbaths are not properly cleaned or are contaminated, they can serve as a reservoir for Mycobacterium fortuitum, posing a risk to individuals who frequently use these services. Infections can manifest as lesions or ulcerations on the skin, particularly in individuals with compromised skin integrity. The other organisms listed do not share the same level of association with nail salon-related infections. For instance, while Staphylococcus aureus is a common skin pathogen, it is not specifically linked to these types of infections. Escherichia coli, primarily associated with gastrointestinal infections, and Clostridium difficile, known for its role in antibiotic-associated diarrhea, are not typically associated with skin infections from footbaths. Thus, Mycobacterium fortuitum stands out as the correct organism linked to this specific scenario.