Evaluation of Urease Activity by the Human Ureaplasma Species

Ureaplasma species are potentially pathogenic bacteria. Ureaplasma can cause inflammation of the genitourinary system, obstetrical complications and can play a role in pathology of the respiratory tract of premature newborns. The aim of this study was to evaluate the urease activity of the human Ureaplasma species in vitro. Urease plays a key role in Ureaplasma cells because its activity is the sole source of ATP production. It is considered that urease is one of the virulence factors of these bacteria. We examined the ammonia product of urea hydrolysis by U. parvum and U. urealyticum strains in two cell culture systems: A549- human lung carcinoma cells and SiHa – human cervical carcinoma cells and in PPLO broth as a control. Urease activity was assessed by measuring the concentration of ammonia, which was based on the measurement of pH in cell culture medium and PPLO broth. Significantly higher concentrations of ammonia were obtained for U. urealyticum as compared with U. parvum only in A549 cells (Mann-Whitney U test P<0.0001). High ammonia levels observed after inoculation of human cells with U. urealyticum suggest higher activity of the urease of this species and may indicate a higher pathogenicity of this species particularly for the human respiratory tract.