What is Ureaplasma spp?
Ureaplasma spp. refers to a genus of small, fastidious bacteria that commonly colonize the lower urogenital tract, comprising two species: Ureaplasma urealyticum and Ureaplasma parvum. 1
Microbiological Characteristics
Ureaplasma species are among the smallest self-replicating organisms, lacking a cell wall and requiring specialized culture conditions for detection 2
The genus includes 14 known serotypes divided into two biovars: U. parvum (biovar 1) and U. urealyticum (biovar 2) 2
These organisms produce urease enzyme, which can lead to stone formation in the urinary tract 3
Key virulence factors include phospholipases A and C, IgA protease, urease, and surface proteins encoded by the Multiple Banded Antigen (MBA) gene 2
Clinical Significance and Pathogenic Role
Urogenital Infections
The pathogenic role of Ureaplasma spp. in urethritis remains debated, with recent evidence from the European Association of Urology suggesting that U. urealyticum, but not U. parvum, is an etiological agent in non-gonococcal urethritis (NGU) 1
Ureaplasma spp. are implicated in 20-40% of NGU cases, though they are also frequently isolated from asymptomatic individuals 1
The controversy stems from historically high colonization rates in the urethra of seemingly healthy men, making it difficult to distinguish colonization from true infection 4
Common Colonization vs. Infection
Ureaplasma spp. are the most prevalent genital Mycoplasma isolated from the urogenital tract of both men and women, with overall prevalence rates of approximately 31-38% in some populations 5, 2
Prevalence is significantly higher in females than males, with the highest positive rates observed in individuals aged 14-20 years 5
Culture or NAATs for Ureaplasma are not recommended for routine screening because of the high prevalence of colonization in asymptomatic, sexually active people 1
Associated Conditions
Beyond urethritis, Ureaplasma infections are associated with:
- Adverse pregnancy outcomes including chorioamnionitis and preterm labor 6, 2
- Neonatal infections, chronic lung disease, and retinopathy of prematurity 2, 7
- Infertility in both men and women 2, 4
- Rarely, invasive infections such as renal abscesses, meningitis, mediastinitis, and suppurative arthritis 6, 7
Invasive Ureaplasma infections occur predominantly in patients with humoral immunodeficiency, either congenital or iatrogenic (such as those receiving rituximab) 6
Diagnostic Considerations
Diagnosis relies on specialized culture techniques or molecular methods (PCR/NAATs), as these organisms are fastidious and difficult to grow 2
Commercial assays are available with improved turnaround time, though interpretation must account for high colonization rates 2
Testing should be reserved for specific clinical scenarios rather than routine screening, given the difficulty distinguishing colonization from true infection 1
Antimicrobial Susceptibility
Josamycin, tetracycline, doxycycline, and pristinamycin maintain exceptionally high activity against both Ureaplasma spp. and M. hominis, with overall resistance rates <5% 5
Fluoroquinolones (ofloxacin and ciprofloxacin) show limited activity, with overall resistance rates >70% and increasing resistance trends 5
Resistance patterns vary between biovars, with biovar 2 (U. urealyticum) maintaining higher sensitivity rates to most antibiotics 2
Doxycycline 100 mg orally twice daily for 7 days is the recommended treatment for NGU, which covers Ureaplasma when it is a true pathogen 1
Important Clinical Pitfalls
Do not treat asymptomatic colonization: The high prevalence in healthy individuals means positive tests do not always indicate disease requiring treatment 1
Consider patient-specific risk factors: A risk-based approach is emerging for determining when Ureaplasma represents true pathogenicity versus colonization 4
Avoid fluoroquinolones for empiric treatment: Given high resistance rates, these should not be first-line agents 5