beta-lactamase

[ bā′tə-lăktə-mās′, -māz′ ]

n.

Any of various enzymes that are produced by gram-negative bacteria and hydrolyze lactam rings, thereby inactivating penicillin and cephalosporin antibiotics. cephalosporinase penicillinase
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.