Which statement is NOT true about Aeromonas hydrophila?

Which statement is NOT true about Aeromonas hydrophila?

• A. Beta-hemolytic
• B. ONPG negative
• C. Catalase positive
• D. Oxidase positive

Answer: (B)

Aeromonas hydrophila shows several lab traits that help identify it, including its hemolysis pattern and key enzyme activities. On blood agar, it typically displays beta-hemolysis, so that statement is true. The ONPG test detects beta-galactosidase activity; Aeromonas hydrophila usually has this enzyme, making the ONPG test positive. Therefore, the claim that it is ONPG negative is not true. It is also catalase positive, meaning it produces bubbles when exposed to hydrogen peroxide, and oxidase positive, indicating the presence of cytochrome c oxidase. These latter two traits are true as well.