Filament formation of Porphyromonas and Prevotella cells induced by β-lactam antibiotics

Abstract

We studied the filament formation of periodontopathic bacterial cells induced by β-lactam antibiotics, and the macropharge phagocytosis of these cells. Nine β-lactam antibiotics, 5 species of Porphyromonas (6 strains), 6 species of Prevotella (6 strains), and rat peritoneal macrophages were used. Cells of 6 Prevotella strains were markedly elongated by 1/64〜1/2MIC of aztreonam (AZT) treatment. Cells with long filaments of 5 of the Porphyromonas strains were observed after treatment with the same concentration of latamoxef, piperacillin and cefteram. All of the β-lactam used caused cells of the treated bacterial strains to form spheroplasts. The phagocytosis ratio and phagcytosis index of macrophages to elongated cells that resulted from the AZT treatment were reduced one half and one third, respectively, compared with normal cells. These results suggest that Porphyromonas and Prevotella cells were elongated after subMIC treatment with certain β-lactam anatibiotics. In addition, these cells became more resistant to macrophage phagocytosis.