Mycoplasma hominis (M. hominis) is a well recognized extragenital path
ogen. Its role as a pathogen of the respiratory tract, however, remain
s difficult to determine. Four cases of pneumonia are presented in whi
ch M. hominis was isolated from blood, tracheal aspirates or post-mort
em lung tissue. All 4 of these isolates were in young Aboriginal adult
males. M. hominis is the least fastidious of the human mycoplasmas an
d grows well on most blood-containing bacteriological media. The recog
nition and identification of M. hominis is important as it is commonly
resistant to erythromycin which would be the drug of choice in most a
typical pneumonias. Early recognition and treatment with tetracycline
instead may influence outcome.