In rapid beta-lactamase testing, what indicator is commonly used to detect penicilloic acid production?

In rapid beta-lactamase testing, what indicator is commonly used to detect penicilloic acid production?

• A. pH indicator
• B. Fluorescent dye
• C. Amber color indicator
• D. Urinin dye

Answer: (A)

Penicillinase activity is detected by following the chemical changes after the beta-lactam ring is opened in penicillin. Penicilloic acid formation is accompanied by acid production, which lowers the pH of the test medium. A pH indicator is added so that this drop in pH causes a visible color change, signaling that beta-lactamase is present and active. This makes the assay rapid and easily read without specialized equipment. Other options like fluorescent dyes or precolored indicators are not standard for this specific acid-detection approach, and an amber color indicator or urine dye are not typical indicators used in penicillinase testing.