Yasumasa Saiki

Study of pathogens of odontogenic infection using an oral floor abscess model in the mouse. Comparison of pathogenicity.

In present study, the pathogenicity of Streptococcus constellatus, Peptostreptococcus micros, Prevotella intermedia, and Fusobacterium nucleatum, which are implicated in odontogenic infection, was determined using an oral floor abscess model in mice. The potential to kill mice, the ability to form an abscess, and the lesion type were used as indices of pathogenicity. The results showed that F. nucleatum was more pathogenic than the other pathogens. It appeared that P. micros and P. intermedia acted aggressively and destructively when the mice were challenged with a sufficient number of these pathogens. Moreover, it appeared that P. intermedia caused a spreading inflammatory lesion that spread to the surrounding tissue via spaces in the oral floor tissue. The present study suggests that pathogens responsible for odontogenic infection differ with respect to pathogenicity.

Study of bacteria isolated from infections of the oral and maxillofacial region. Part 3: Relations between the clinical symptons and the isolation of organisms.

A total 150 patients with obstructed abscesses in the oral and maxillofacial region were studied with respect to the relation between clinical symptons and the isolation of organisms.Various kinds of anaerobes were isolated from almost all patients. Mixtures of grampositive cocci and anaerobic gram-negative rods were most frequent in severe cases. Patients in whom few organisms were isolated were characterized by chronic, mild inflammation and prior chemotherapy. All patients with postoperative maxillary cysts had chronic infectionsThe results suggested that anaerobes were necessary for the occurrence of infection in the oral and maxillofacial region and that pathogenic synergy between gram positive cocci and gram negative rods contributed to increased severity of infection.

Study of bacteria isolated from infections of the oral and maxillofacial region. Part 2. Anaerobes.

Eighty-six cases of obstructed abscesses in the oral and maxillofacial region were studied bacteriologic ally.Isolated anaerobic organisms were identified in detail and assessed with regard to antimicrobial susceptibility to several agents. Anaerobes were isolated from approximately 95% of cases that had isolated organisms. Gram-positive cocci, including Peptostreptococcus and Gemella, and gram-negative rods, including Prevotella, Porphyromonas, and Fusobacterium, were isolated frequently. As for antimicrobial susceptibility, some strains of Prevotella were resistant to β-lactam agents. In particular, many strains of Fusobacterium were resistant to erythromycin. Clindamycin and levofloxacin were highly active against anaerobes isolated from infections in the oral and maxillofacial region.Our results suggest that anaerobes as well as Streptococcus should be considered when treating infections in the oral and maxillofacial region.