グラム陰性桿菌のβ-lactam抗生剤不活化物質とその新簡易測定法

Abstract

Each strain of E. coli, Klebsiella, Enterobacter, Serratia and Pseudomonas, isolated from clinical materials in recent years was cultured in heart infusion broth, and the broth culture was sterilized with membrane filters. Then, the amounts of PC-G, AB-PC, CB-PC, SB-PC, MCI-PC, CET, CER, CEX and CEZ inactivated with 1 ml of the filtrate were examined. The antibiotics of PC group tended to be inactivated by the filtrate in the following order: PC-G<AB-PC<CB-PC=SB-PC<MCI-PC. The antibiotics of Cephalosporin group were as follows: CER<CET=CEZ<CEX.The measurement of amounts of AB-PC and CET inactivated with 1 ml of the filtrate after 48 hours culture of various kinds of GNR, showed that most Klebsiella strains mainly inactivated AB-PC, and that most Serratia and Pseudomonas strains inactivated CET. About a half of the Enterobacter strains inactivated CET and the other half of them inactivated both AB-PC and CET. Among E. coli, Klebsiella and Enterobacter strains, the strains which inactivated-both AB-PC and CET showed extremely high values of inactivating amounts; many strains had the ability to inactivate several ten thousands to 300, 000μg. It was confirmed that the inactivating ability of the antibiotics was demonstrated to be accumulated in the broth culture with time.“Double Disc Method”, a simplifiedbiological method for assay of β-lactam antibiotic inactivating substance of GNR, was developed in our laboratory. In this experiment, a close relationship was observed between the results with this method and the antibiotic inactivating ability produced in the bacterial culture filtrate, and its availability of clinical application was suggested. In addition, it was considered that β-lactam antibiotic inactivating substance in this experiment was attributable mainly to β-lactamase.