RESUMEN
BACKGROUND: Mycoplasma pneumoniae is the species that is considered pathogen for respiratory tract. Other species, M. hominis and U. urealyticum, have been isolated from respiratory specimens and its aetiological relation with respiratory infections is not clear. METHODS: In this study, mycoplasma from respiratory specimens have been isolated from HIV infected patients, patients suffering from chronic bronchitis and patients with respiratory infections without any underlying disease, using SP-4 media and being identified with glucose fermentation test, guinea pig blood cells adsorption, tetrazolium reduction, urea test, arginine test, and antigenic study by an immunoassay on the colonies grown on SP-4 solid medium. RESULTS: M. hominis has been the species most frequent isolated, mainly from patients without any underlying disease and from HIV infected patients, and less frequently from patients suffering from chronic bronchitis, the differences between both groups being significative. Other Mycoplasma, no identified at he species level, have been isolated although without any significative differences. In only one case U. urealyticum has been isolated. CONCLUSIONS: No M. pneumoniae isolation was obtained.