.beta.-Lactamase inhibitor EM4615
 A substance which inhibits the enzyme .beta.-lactamase, produced by a wide range of microorganisms, is obtained when species of the microorganism Micromonospora are cultivated under aerobic fermentation conditions and this inhibitor can be isolated from the fermentation medium by extraction. This substance, denominated EM4615, is useful to enhance the effectiveness of .beta.-lactam antibiotics such as penicillins and cephalosporins. 
E. R. Squibb & Sons, Inc.
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Wen C. Pacifico A. J. Scott Richard B.
Liu Principe Wells Sykes