M. genitalium was phagocytosed rapidly by human monocyte-derived macrophages resulting in a loss of bacterial viability. Primary human MDM were inoculated with log-phase M. genitalium G37 or M2300 (MOI 100) and collected just after inoculation or 30 min or 6 h PI and processed for TEM. Viable extracellular M. genitalium with dense intracellular ribosomes and an intact outer membrane were observed at the time of inoculation (A). Thirty minutes following inoculation, phagocytosis of M. genitalium was observed with localization to phagolysosomes (arrow) and morphological changes of the bacterium (B). By 6 h PI, macrophages contained many phagocytic vacuoles (arrows) and no intracellular mycoplasmas could be located (C). Micrographs depict M. genitalium strain G37 but similar findings were observed for strain M2300. N denotes nucleus.