American Board of Internal Medicine (ABIM) Certification Practice Exam

How is bacterial overgrowth syndrome diagnosed in patients with systemic sclerosis?

1. Endoscopy and biopsy

2. Glucose hydrogen breath test

3. Stool culture

4. Serum glucose test

The correct answer is: Glucose hydrogen breath test

Bacterial overgrowth syndrome in patients with systemic sclerosis is primarily diagnosed using the glucose hydrogen breath test. This test works by measuring the amount of hydrogen that is produced in the breath after the ingestion of glucose. When bacteria overgrow in the small intestine, they ferment carbohydrates, including glucose, leading to increased hydrogen production. This hydrogen is then absorbed into the bloodstream and eventually exhaled in the breath. The glucose hydrogen breath test is particularly useful in this context because it is non-invasive and can provide quick results. It specifically assesses the functioning of the small intestine and identifies excessive bacterial fermentation that is characteristic of bacterial overgrowth. Other diagnostic methods, such as endoscopy and biopsy, may be used in broader gastrointestinal evaluations, but they are more invasive and typically not the first-line diagnostic tools for bacterial overgrowth. Stool cultures are generally used to identify specific pathogens but are less effective in diagnosing bacterial overgrowth specifically. Serum glucose tests do not provide direct insight into bacterial overgrowth and are not used for this purpose. Thus, the glucose hydrogen breath test is the most appropriate and effective diagnostic tool for identifying bacterial overgrowth syndrome in patients with systemic sclerosis.