“…Early methods relied on presumed tissue or host affinities, presumed unique epidemiology, or on specific serology, all characteristics of host response to chlamydiae. In the mid-l960s, phenotypic traits of specific chlamydial strains were identified : glycogen accumulation and sulfadiazine sensitivity (Gordon & Quan, 1965;Lin & Moulder, 1966). These characteristics and inclusion morphology became the basis for the description and differentiation of C. trachomatis and C. psittaci species (Page, 1968 (Cox et al, 1988;Fukushi & Hirai, 1989Grayston et al, 1989).…”