A SIMPLE METHOD FOR THE DETERMINATION OF THE DRUG-INACTIVATING ACTIVITY OF BACTERIA USING SENSITIVITY DISCS
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- KANAZAWA YUTAKA
- Department of Internal Medicine, Niitsu Medical Centre Hospital
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- SHIGENO KAZUKO
- Laboratory of Bacteriology, Niitsu Medical Centre Hospital
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- KURAMATA TOSHIO
- Nichiei Co., Ltd.
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説明
The effect of antibacterial chemotherapy is influenced by the drug-susceptibility (minimum inhibitory concentration: MIC or minimum bactericidal concentration: MBC) of a bacterium and the drug concentration in an infected focus. An intracellular drug-inactivating activity is reflected generally by the value of MIC, while an extracellular inactivating activity, which may affect focal drug-concentrations, is usually overlooked.<BR>β-Lactamase, an inactivating enzyme, is usually detected using benzylpenicillin1, 2) or chromogenic cephalosporin3, 4) as a substrate. From the clinical point of view, however, it seems more appropriate to observe the direct reactionship between the isolated causative organism and the drug used.<BR>No readily-applied simple method has been reported in any combination between bacteria and drugs for such a direct observation. In this paper, we intend to present a simple and routine method for the determination of the drug-inactivating activity of living cells.<BR>We have studied a simple method which we call “the cell-disc system” that satisfies the above requirements and permits an easy measurement of the extracellular drug-inactivating activity of any bacteria against any drugs using ordinary sensitivity discs containing the drugs in question. KANAZAWA et al. 5) have previously reported a method which permits classification of degrees of drug inactivation by comparing the sizes of inhibition zones produced by sensitivity discs on preinoculated agar plates and uninoculated plates. TOMIOKA et al. 6) reported a “double disc technique” for a semiquantitative assay for β-lactamase production by Gram-negative bacteria. Recently, Tsun et al.7) presented an assay technique for β-lactamase substrate-profiles using an agar plate consisting of a base-layer containing crude enzyme, sensitivity discs and a top-layer inoculated with an indicative organism.<BR>In this paper we describe 2 simple systems based on the measurement of clear inhibition zones around ordinary sensitivity discs to quantitatively determine degrees of drug-inactivation caused by test bacteria.
収録刊行物
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- The Japanese Journal of Antibiotics
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The Japanese Journal of Antibiotics 39 (3), 823-841, 1986
公益財団法人 日本感染症医薬品協会
