Regulations last checked for updates: Feb 12, 2026

Title 21 - Food and Drugs last revised: Dec 18, 2026
§ 866.2850 - Automated zone reader.

(a) Identification. An automated zone reader is a mechanical device intended for medical purposes to measure zone diameters of microbial growth inhibition (or exhibition), such as those observed on the surface of certain culture media used in disc-agar diffusion antimicrobial susceptibility tests. The device aids in decisionmaking respecting the treatment of disease.

(b) Classification. Class I (general controls).

authority: 21 U.S.C. 351,360,360c,360e,360j,360
cite as: 21 CFR 866.2850