Attachment of Mycoplasma hominis to human cell cultures

Clinical isolates, cell-culture contaminants, and the type strain PG21 of Mycoplasma hominis were examined for attachment to erythrocytes and human cell cultures. Strain 13428 (from blood, postpartum fever) and strain 1184 (cell culture) attached to human and guinea pig erythrocytes, but there were no differences in attachment activities between these strains. However, five M. hominis strains isolated from different tissue sites showed quantitative differences in attachment to human WiDr (intestinal carcinoma cell cultures), MRC-5 (human embryonic lung fibroblasts) and HeLa (carcinoma of cervix) cell cultures. The relative attachment activities were, in descending order: strain 1184 (cell culture), strain 11932 (cervix), strain 13428 (blood, postpartum fever), 13408 (nongonococcal urethritis), and type strain PG21 (multiple passage, originally from human rectum). Trypsin and pronase treatment of M. hominis strain 1184 markedly reduced attachment, suggesting that surface proteins play a role in M. hominis attachment to mammalian cells. In subsequent studies, strain 1620 (septic arthritis) showed the highest attachment activity, whereas strain 1652 (surgical skin flap) and L01888 (cell culture) showed attachment activity similar to cell culture strain 1184. The differing attachment activities of these M. hominis strains isolated from different infected sites of patients with a variety of diseases may be relevant to the virulence of these strains.