Chlamydiae. Nota I.

Throughout the animal kingdom the Chlamydiae are among the most common and ancient pathogens, but only in the 1966 they were classified by Page in the same genus because of different nosological pictures that they cause, while more recently were identified as bacteria. Chlamydiae have been divided into two species: C. trachomatis and C. psittaci. In 1986 Grayston et al. proved the etiological role of a "new chlamydial strain", named TWAR (Taiwan-Acute Respiratory), in human pneumonia and bronchitis; TWAR is distinguishable from other Chlamydiae and possibly represents a new entity. The Chlamydiae are non-motile, metabolically poor bacteria, completely lacking of any enzimatic system for energy production (ATP) and for this reason are obligate intracellular parasites; they poses group-specific, species-specific and type-specific antigens. Four series of surface proteins were identified as responsible for their pathogenic properties, while many Authors consider a particular lipopolysaccharidical acid, group antigen, as a real LPS. These bacteria poses an unique developmental cycle with production of two type of particles different for metabolic and infecting characters: elementary body and reticulate body. The Chlamydiae have a broad spectrum of host. They cause persistent or chronic infections and their survival is insured by the elementary body. The Chlamydiae stimulate the humoral and the cellular-mediate immunity system and are capable of survival in the monocytes and macrophages.