CYTOPATHOGENICITY OF MYCOPLASMA-FERMENTANS (INCLUDING STRAIN INCOGNITUS)

Mycoplasma fermentans strain incognitus, an organism recently identifi ed in tissues of patients with AIDS and in tissues of otherwise health y adults with an acute fatal respiratory disease, was evaluated for cy topathogenicity for tracheal tissue in vivo and in vitro. In this stud y, the organism produced a chronic infection of the lower respiratory tract in LEW rats following intranasal inoculation and induced both ci liostasis and cytopathology in experimentally infected tracheal explan ts from rats. The time of onset of ciliostasis, type of cytopathogenic ity, and localization of organism in strain incognitus were different from those in other strains of M. fermentans as well as other species of mycoplasmas isolated from humans. The results strongly support, but do not prove, that M. fermentans strain incognitus is an unusually in vasive mycoplasma, as it was the only strain found within respiratory epithelial cells both in vivo and in vitro. Detection of the organism within the lamina propria also supported the organism's invasive poten tial. Further study of both the in vivo and in vitro models should pro vide insights into this potentially unique mycoplasma-host relationshi p.