Figure 1: Invasiveness of P. acnes into epithelial cells. HEK293T cells infected with one of the serotype 1 P. acnes strains isolated from sarcoid lymph nodes were Giemsa stained (a) and further examined by electron microscopy (b). The electron micrographs of the cells infected with an invasive isolate show intracellular localization of the bacterium (indicated by the red arrows).