Fleming P C, Goldner M, Glass D G
J Bacteriol. 1969 May;98(2):394-7. doi: 10.1128/jb.98.2.394-397.1969.
Cephalosporinase (beta-lactamase) was obtained from cell washings of Aerobacter (Enterobacter) cloacae as a highly active preparation. An alkalimetric method was used to determine the enzyme activity and to estimate its inhibition by 6-amino-penicillanic acid derivatives. Their order of decreasing inhibitory effect was as follows: cloxacillin, oxacillin, methicillin, ampicillin, and penicillin G. We found that 2 to 3 ng of cloxacillin per ml was sufficient to decrease the enzyme activity by 50% in the presence of 400 mug of cephalosporin C per ml. Cloxacillin exerted a potentiating effect on the inhibition of the E. cloacae organisms by cephalosporin C.
头孢菌素酶（β-内酰胺酶）是从阴沟肠杆菌（产气肠杆菌）的细胞洗涤液中获得的一种高活性制剂。采用碱量法测定酶活性，并评估6-氨基青霉烷酸衍生物对其的抑制作用。它们的抑制作用递减顺序如下：氯唑西林、苯唑西林、甲氧西林、氨苄西林和青霉素G。我们发现，在每毫升含有400微克头孢菌素C的情况下，每毫升2至3纳克的氯唑西林足以使酶活性降低50%。氯唑西林对头孢菌素C抑制阴沟肠杆菌具有增效作用。
