Cultivation of fastidious mycoplasmas from human arthritis

14 joint fluid specimens from arthritic patients and 8 synovial tissue specimens from traumatic joint lesions were studied for mycoplasmas. Fastidious slow-growing mycoplasmas were cultivated from arthritic patients but not from the controls. Using a large field microscope and a lens correcting the thickness of the Dienes-stained agar block preparations, tiny granular colonies with a diameter of 15-50 micrometers were seen. The isolates were arginine-positive but glucose- and urea-negative. In growth inhibition tests there was a partial inhibition zone of 1-10 mm by M. hominis type 2 and M. arthritidis immune sera. Thus the isolates resembled mycoplasmas previously recovered from acute and chronic human arthritis in Finland.