Serological analysis of Actinomyces viscosus and identification of pathogenic human strains

Abstract

Granular organisms were isolated from human dental plaque in an isolation medium of nutrient agar and 0.5% propionic acid under anaerobic conditions by Onisi et. al. These organisms are Gram-positive branching filaments and produce viscous material around the cells from the medium. They ferment soluble starch and rapidly turn it acid. Granular organisms grow with dense granules in the filamentous cell and look like a rosary. They resemble in shape and nature Actinomyces viscosus, which induces periodontal disease in experimental animals.In this paper, these oranisms are studied using serogical techniques. The organisms are compared with Actinomyces viscosus originating from hamsters andActinomyces naeslundi isolated from the human mouth.Scanning electron microscopic photographs revealed similarities between the granular organisms and Actinomyces viscosus in shape, size, and the pattern of the material deposited on the filamentous cells. According to biochemical tests, the organisms are divided into three groups; the Actinomyces viscosus group, the Actinonzyces naeslundi group, and the rest of the granular organisms. These granular organisms are then compared to other Actinomyces species. They do not hydrolyze potato starch as does Actinomyces bovis. They do not accumulate dark red pigment in mature colonies on horse blood agar as does Actinomyces odontolyticus. Actinomyces israelii forms “molar tooth” colonies and these granular organisms do not. Antisera against Actinomyces viscosus and Actinomyces naeslundi agglutinated all granular oranisms. Vice versa, antiserum against granular organism no. 39 agglutinated Actinomyses viscosus and Actinomyces naeslundi. Immunoelectrophoretic analysis of Lancefield antigen of the orgamisms against anti Actinomyces viscosus and Actinomyces naeslundi resulted in three patterns of antigen characteristic to Actinomyces viscosus, Actinomyces naeslundi and Actinomyces viscosus variant. IEP patterns of the homogenized antigen against anti Gr. 39 strain serum are divided into four groups. The first group includes catalase (-) organisms, the second, catalase (+), the third group, Actinomyces naeslundi, and the last group includes Actinomyces viscosus.Specific antisera against organisms were prepared using the absorption technique. Specific antisera after absorption procedure showed that Actinomyces viscosus and Actinomyces naeslundi have the specific antigens V and N, and the granular organisms also have the specific antingens H and H', and Iw. The granular organisms are considered to be species of Actinomyces and might belong to the cluster consisting of Actinomyces viscosus and its most closely related Actinomyces naeslundi, because their similarities are so great in serological reactions, morphology, and life cycle.Almost all the granular organisms isolated from rats, hamsters and guinea pigs are shown to have the V antigen. Eighty percent and forty-eight percent of the organisns recovered from human and monkey mouths have both H and N antigens.To discover the type of the Actinomyces concerned in periodontal disease, the dental plaque of patients with periodontal disease were examined. Dental plaque was obtained from pockets more than 3 mm deep. Actinomyces with Iw antigen is characteristic of these pockets. The major isolates from people without any sign of gingival disorder wese the NH' type strain. The major type of the isolates from babies (7 mon. -3 yr 10 mon) was also NH' rype.