RESUMEN
M. hominis and U. urealyticum are the better-known mycoplasma species pathogenic to the human genitourinary tract, causing mainly urethritis, bacterial vaginosis and pregnancy complications. In HIV-infected patients, the prevalence and role of these species is still not well known. The aim of this work was to determinate the prevalence of these species in this group of male patients (HIV group), in comparison to a group of men with clinical symptoms of urethritis (STD group). M. hominis was isolated from 7.5 per cent patients (8/106) and U. urealyticum from 18.9 per cent patients (20/106) from the HIV group, being among these 62.5 per cent and 85 per cent in significant concentrations, respectively. In the STD group these rates were 0.9 per cent (1/110) for M. hominis and 13.6 per cent (15/110) for U. urealyticum, being 100 per cent and 93.3 per cent in significant concentrations, respectively. We could demonstrate infection rates by these mycoplasma species in the HIV group as high as the one found in the STD one, what may indicate the occurrence of opportunistic infections in our population. This fact is discussed here because in immunosuppressed patients, specially M. hominis has been reported causing severe infections, even systemically.