ASCP MLT Practice Exam 2025 – Comprehensive Prep Guide

The correct answer highlights bacteria that are known to produce acetoin during glucose fermentation, resulting in a positive Voges-Proskauer (VP) test. The VP test is used to identify organisms that can convert pyruvate to acetoin in their metabolic processes.

Klebsiella, Enterobacter, and Serratia are known for their ability to ferment glucose and produce this intermediate, which is detected as a positive result in the VP test. The presence of acetoin is visualized through a reaction with α-naphthol and potassium hydroxide, producing a red color in the test medium.

In contrast, Escherichia coli is typically VP negative as it primarily produces mixed acids rather than acetoin during fermentation. Staphylococcus aureus is not typically tested for in this manner as it does not have a significant pathway that yields acetoin, and Salmonella species generally do not produce acetoin either. Thus, the correct identification of VP-positive bacteria in this context is limited to the organisms listed in the correct answer.