口腔 Bacteroides species の β-lactamase に関する研究
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概要
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For the purpose of assessment of production of β-lactamase, the bulk of pus samples collected from oral lesions (11 cases) and dental plaque of gingival crevice from 30 cases of patients and 23 cases of healthy adults were cultured. Then the β-lactamase activity in each culture was determined by iodometric method using CER and PCG as the substrates. Attempts were made to further isolate and identify the β-lactamase-producing strains from the positive cultures concerning β-lactamase production. Subsequently, β-lactamase was purified from one of the isolated strains, Bacteroides intermedius. The results obtained were as follows : 1. Out of the 64 above mentioned cultured samples, 4 pus samples and 10 dental plaque samples (21.9%) were found to contain β-lactamase. 2. The anaerobic strains which produced β-lactamase were of either black-pigmented or non-pigmented Bacteroides group. 3. The black-pigmented and non-pigmented Bacteroides strains which elabolated β-lactamasewere identified to be B. intermedius and Bacteroides heparinolyticus, respectively. 4. MICs of CER and PCG against both species of Bacteroides were rather high and there was a good correlation between the degree of β-lactamase production and MIC. 5. The majority of β-lactamase activity was found in the cell extract prepared by ultrasonic treatment, especially in the precipitate by ultracentrifugation including membrane fraction. No significant amount of the activity was detected in the culture fluid. 6. The enzyme could be solubilized from the ultracentrifugal precipitate with Triton X-100. 7. β-lactamase of B. intermedius was a hydrophobic protein with a molecular weight of 93, 000. Its isoelectric point was 4.4. The optimum pH was 7.0. 8. The enzyme was inactivated by heating at 60℃ for 10 min. PGE, TDC, K^+, Mg^<2+>, Zn^<2+>, Cu^<2+> and Fe^<2+> gave no effect on the activity, but it was inhibited by SDS, 1, 10-phenanthroline, or iodine. 9. The enzyme hydrolyzed cephem antibiotics (CER, CEX and CET) more preferably than penicillin group antibiotics including PCG, ABPC and CBPC. It was confirmed B. intermedius and B. heparinolyticus which were β-lactamase positive and resistant to various β-lactam antibiotics resided in the oral cavity. This enzyme may be membrane-bound and categorized in cephalosporinase. These findings indicate that great care should be taken in chemotherapeutic treatment for oral infections.
- 九州歯科学会の論文
- 1987-02-25
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関連論文
- 口腔 Bacteroides species のβ-lactamase に関する研究 : 主論文の要旨
- 口腔 Bacteroides species の β-lactamase に関する研究
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