Influence of urease present in non viable organisms on the decline phase of Ureaplasma growth.

Broth cultures infected with ureaplasmas for 48 hrs were unable to support further growth of reinoculated ureaplasmas even when reconstituted with fresh ureaplasma medium. The apparent toxicity of spent cultures was ascribed to the presence of non viable ureaplasmas still containing a fully active urease since all the procedures adopted to abolish or reduce the urease activity restored the ability of these spent cultures to support ureaplasma growth. However, if the cause of the steep decline phase of ureaplasma cells could be reasonably ascribed to the enzymatic activity of urease present in the dead cells, the reasons for the poor field and the low titers achieved by the organisms during the logarithmic phase of growth remain an enigma.