How Ureaplasma is Transmitted
Ureaplasma urealyticum is primarily transmitted through sexual contact, with additional transmission occurring from mother to infant during pregnancy, delivery, or through the birth canal. 1, 2
Sexual Transmission in Adults
- Sexual intercourse is the primary mode of transmission among sexually active adults, with colonization rates increasing directly with the number of different sexual partners 3, 4
- Colonization rates are low (<10%) in sexually inexperienced adults and older children, but increase substantially following sexual debut 4
- The organism colonizes the male urethra and female vagina as its primary sites, with other genital and nongenital mucosal sites colonized less frequently 4
- Approximately one-third of healthy sexually experienced adults carry U. urealyticum as part of their normal urogenital flora 4
Perinatal Transmission Routes
Pregnant women transmit U. urealyticum to their newborns through three distinct pathways 5:
In Utero Transmission
- Transplacental spread from the mother's bloodstream to the fetus 5
- Ascending infection from the mother's colonized urogenital tract, even with intact fetal membranes—ureaplasmal infection of the amniotic sac without membrane rupture is well-documented 5
Intrapartum Transmission
- Passage through a colonized birth canal during vaginal delivery 5
- Vertical transmission occurs in 18-55% of full-term infants and 29-55% of preterm infants 5
- Cesarean section does NOT prevent transmission—colonization occurs even with cesarean delivery and intact membranes 5, 6
- Duration of membrane rupture (≥12 hours vs. <12 hours) does not significantly affect transmission rates 6
Postnatal Transmission
- Horizontal or nosocomial transmission can occur after birth 5
- Colonization persists in many infants: 68% of throat-colonized, 33% of eye-colonized, and 37% of vagina-colonized infants remain colonized at 3 months of age 6
Important Clinical Context
- Transmission does not equal disease—U. urealyticum frequently colonizes healthy individuals without causing symptoms, existing in a "gray zone" where it is not classified as a traditional STD like gonorrhea or chlamydia 2
- The presence of chorioamnionitis significantly increases vertical transmission rates from mother to infant 5
- Very-low-birth-weight (VLBW) infants have higher colonization rates compared to term infants 5
- Immunosuppressed patients are at increased risk of invasive infections when colonized 7