Mycoplasma penetrans
A species of gram-negative, facultatively anaerobic bacteria. This organism shows remarkable pathobiologic properties: it adheres to cell surfaces, deeply penetrates into the cell, and strongly adsorbs human red blood cells and human CD4+ lymphocytes and monocytes. M. penetrans was first isolated from the urogenital tract of patients with AIDS and high frequencies of antibodies to it are seen in HIV-infected patients.