Ureaplasma urealyticum infection

The Mycoplasma class of bacteria are known as Mollicutes in the order of Mycoplasmatales and in the family of Mycoplasmataceae. Within this family there are 2 genera which are Mycoplasma and Ureaplasma. Currently 13 species of Mycoplasma are known to affect humans and 2 species of Ureaplasma can affect the lower genital tract.

Taxonomy of Mycoplasma species:
          Class           Mollicutes
          Order           Mycoplasmatales
          Family         Mycoplasmataceae 
                                       • Mycoplasma           Mycoplasma pneumoniae 
                                                                          Mycoplasma fermantans 
                                                                          Mycoplasma primatum 
                                                                         Mycoplasma hominis 
                                                                         Mycoplasma genitalium
                                       • Ureaplasma         Ureaplasma urealyticum 
                                                                        Ureaplasma parvum

The Mycoplasma species are a group of microorganisms that can involve the respiratory and genital tracts in man to produce clinical disease:
          • Respiratory:          Mycoplasma pneumoniae cause of atypical pneumonia
          • Genital tract:         Mycoplasma fermantans 
                                           Mycoplasma primatum 
                                           Mycoplasma hominis 
                                           Mycoplasma genitalium 
                                           Ureaplasma urealyticum 
                                           Ureaplasma parvum

In the female genital tract the Ureaplasma species & Mycoplasma hominis can be pathogenic and can cause the following complications:
          • Pregnancy: - spontaneous miscarriage
                                 - stillbirths
                                 - postpartum infection
                                - chorioamnionitis 
                                - preterm labour
                                - preterm rupture of membranes
                               - neonatal infection 
         • Gynaecology: - pelvic inflammatory disease
                                    - infertility
                                   - vaginal discharge

In the male genital tract the Ureaplasma species and in particular Mycoplasma genitalium can be the cause of:
          • Male: - non-specific urethritis
                       - male factor infertility

The Mycoplasma organisms are a form of bacteria but lack a cell wall. They require stringent conditions for survival as intracellular pathogens within the body. Mycoplasma hominis may be found in association with Ureaplasma species and both organisms are aquired as sexually transmitted infections.

The diagnosis of Ureaplasma infections of the lower genital tract can be difficult as the organisms do not grow in the usual culture medium but require specific enrichment media for identification. In the male adequate specimens are difficult to obtain and Mycoplasma genitalium in particular cannot be cultured at all but is able to be identified by molecular PCR testing which is only carried out in specialized laboratories.

The Ureaplasma organisms have been divided into 2 subtypes of Ureaplasma urealyticum and Ureaplasma parvum but can only be differentiated by PCR testing. The pathogenicity of the Ureaplasma microorganisms within the female genital tract is unclear and in fact many consider them to be part of the normal bacterial flora of the vagina. There is however, no doubt that when these organisms are detected in an appropriate clinical setting, aggressive treatment with antibiotics is strongly recommended in order to prevent complications.

Gardnerella vaginalis is another microorganism that often involves the lower genital tract to cause an offensive vaginal discharge often in association with other organisms including Ureaplasma species and Mycoplasma hominis. The diagnosis of bacterial vaginosis due to Gardnerella vaginalis can be made on cytology identifying the characteristic ‘clue cells’ or on culture of a vaginal swab.

Treatment of Ureaplasma urealyticum is with oral Doxycycline 100mg daily for 28 days with a similar course for the sexual partner. Treatment of Gardnerella vaginalis is with Metronidazole 400mg 3 times daily for 14 days with the partner also being treated. In pregnancy Erythromycin 250mg 3 times daily is the preferred treatment for Ureaplasma species and is usually taken for the duration of the pregnancy.