Microbiology · Intracellular and atypical bacteria
Mycoplasma genitalium / Ureaplasma !
- Bacterium
- Does not Gram-stain
- Exam priority: medium
Genital mycoplasmas: M. genitalium causes persistent urethritis and is increasingly drug-resistant; Ureaplasma is usually a coloniser.
Updated 2026-11-01
At a glance
- Gram
- Does not Gram-stain
- Shape
- Pleomorphic, wall-less
- Oxygen
- Facultative anaerobes
- Family
- Mycoplasmataceae
- Stain
- Do not stain with Gram
Morphology
- No cell wall, like M. pneumoniae
- Ureaplasma hydrolyses urea (urease)
- M. genitalium barely grows in culture
Transmission
- Sexual contact
- Ureaplasma: also mother to baby in pregnancy or birth
Reservoir: Human urogenital tract
Isolation precautions
What the care team adds to standard precautions.
- Standard
Virulence factors
- M. genitalium adheres to urogenital epithelium and causes inflammation
- Mutations conferring resistance to macrolides and fluoroquinolones
- Ureaplasma: pathogenic only at high load or in special settings (preterm infants, immunosuppression)
Diseases it causes
- Non-gonococcal urethritis, especially persistent or recurrent
- Cervicitis and possible pelvic inflammatory disease (M. genitalium)
Clinical picture
- Dysuria and urethral discharge that persists after usual treatment
- Cervicitis with post-coital bleeding
- Ureaplasma has been linked to chorioamnionitis and lung disease in preterm infants
Diagnosis
- NAAT for M. genitalium on urine or swab in recurrent urethritis or cervicitis
- Macrolide-resistance testing when available
- Screening people without symptoms is not recommended
Treatment
Two-step, resistance-guided therapy: doxycycline to lower the load, followed by azithromycin if the strain is macrolide-sensitive or moxifloxacin if resistant. Macrolide resistance is very high, and single-dose azithromycin drives it.
Drug class only; doses and regimens are set by the clinician from the current guideline.
In Pharmacology:
Prevention
- Condoms
- Evaluation and treatment of sexual partners
Test yourself
Think of the answer, then tap the question to see it.
Which organism is suspected in persistent non-gonococcal urethritis?
Mycoplasma genitalium, the most frequent cause of persistent or recurrent urethritis.
Why is single-dose azithromycin avoided for M. genitalium?
Because it selects macrolide-resistant strains and often fails.
Which characteristic enzyme does Ureaplasma have?
Urease, which hydrolyses urea (hence its name).
Related
← Back to the group: Intracellular and atypical bacteria
Educational content on microorganisms; not a treatment guide and no substitute for a health professional's advice. No doses are given.
Sources: Mycoplasma genitalium - STI Treatment Guidelines (Centers for Disease Control and Prevention (CDC), 2021); Urethritis and Cervicitis - STI Treatment Guidelines (Centers for Disease Control and Prevention (CDC), 2021); Sexually transmitted infections (STIs) (World Health Organization (WHO), 2025).
Spotted a mistake?We are always improving for the community. Tell us what is wrong and our team will review it.Report a mistake
Representative model, for educational purposes only.