Antibiotic resistance of an endodotitis-associated bacterium, Porphyromonas endodontalis.

牙髓卟啉单胞菌，革兰氏阴性，黑色，厌氧棒，被认为与牙髓炎有关。KSEW01是一种非色素变体，来自KSE105，它是从牙髓病变中分离出来的临床菌株，可能是KSEW01的亲本菌株，被发现对糖肽抗生素试剂或达巴肽万古霉素（VCM）具有耐药性，其最小抑制浓度（MIC）大于200马克杯/毫升。为了进一步了解厌氧菌对抗生素的耐药性机制，采用二维聚丙烯酰胺凝胶电泳技术对KSEW01在万古霉素存在和不存在条件下的细胞蛋白进行了比较，以检测可能导致该菌株对抗生素产生耐药性的成分。有VCM培养的细胞有明显斑点，无VCM培养的细胞无明显斑点。遗憾的是，结果不能重复。然后，从KSE105中获得34个vcm抗性突变体，从牙髓假体型菌株ATCC35406中获得5个vcm抗性突变体。用琼脂稀释法测定这些突变体的mic。获得的突变体均为黑色色素。部分突变体对VCM的抗性达到与KSEW01相同的程度（MIC， 200马克/毫升）。KSEW01的3种黑色色素自发复归物均对VCM （MIC, 100 mug/ml）具有抗性。从这些结果来看，色素沉着和VCM抗性没有联系在一起。目前正在研究检测KSE105的地窖成分与抗vcm突变体之间的差异。结果将适用于成人牙周炎的强效病原体，牙龈卟啉单胞菌。

Porphyromonas endodontalis, a Gram-negative, black-pigmented, anaerobic rod, is considered to be associated with endodontitis. A nonpigmentd variant, KSEW01, from KSE105 which is a clinical isolate from an endodontic lesion and is possibly a parent strain of KSEW01, was found to be resistant against a glycopeptide antibiotic reagent, or a dalbaheptide, vancomycin (VCM), of which the minimal inhibitory concentration (MIC) was greater than 200 mug/ml. To help understand the mechanism of the antibiotic resistance in anaerobes, the cellular proteins of KSEW01 which was cultured in the presence of and those in the absence of vancomycin were compared by the two dimensonal polyacrylamide gel electrophoresis to detect the component(s) that might give the antibiotic resistance to this strain. A clear spot which was present in the cell cultured with VCM and absent without VCM was found. Regretfully the result was not reproducible. Then, thirty-four VCM-resistant mutants from KSE105, five from P.endodontalis type strain, ATCC35406, were obtained in vitro. MICs of these mutants were measured by agar dilution method. The mutants obtained were all black-pigmented. Some of the mutants had the resistance against VCM to the same degree (MIC, 200 mug/ml) as that of KSEW01. All the three black-pigmented, spontaneous revertants of KSEW01 were isolated and they were also resistant against VCM (MIC, 100 mug/ml). From these results, pigmentation and VCM resistance were not linked together. The detection of the difference between the cellar components of KSE105 and those of the VCM-resistant mutants are under investigation. The results will be applied to a potent pathogen of adult periodontitis, Porphyromonas gingivalis.