Mycoplasma fermentans--HeLa cell interactions.

A survey of previous evidence for the intracellular localization of mycoplasmas within nonphagocytic cells indicated that it was insufficient to conclude unequivocally that such localization occurred. Illustrations of the seemingly intracellular existence of Mycoplasma fermentans in the tissues of patients with AIDS and other patients rekindled interest in the topic of mycoplasmal entrance into epithelial cells. Accordingly, the "incognitus" and PG18 strains of M. fermentans were sought and demonstrated within HeLa cells by electron microscopy following treatment of the cell cultures with gold-labeled antiserum specific to the mycoplasma, together with ruthenium red staining. The phenomenon is not unique to this mycoplasma, being demonstrated also with Mycoplasma hominis. In hindsight, some of the earlier investigators who hinted at intracellular localization were probably correct in doing so.