The common vaginal commensal bacterium Ureaplasma parvum is associated with chorioamnionitis in extreme preterm labor

Abstract

Objective: To assess the association of vaginal commensal and low-grade pathogenic bacteria including Ureaplasma parvum, Ureaplasma urealyticum, Mycoplasma hominis, Mycoplasma genitalium, Group B streptococcus (GBS), and Gardnerella vaginalis, in women who delivered preterm at less than 37-week gestation in the presence or absence of inflammation of the chorioamnionitic membranes.

Methods: A case control study involving women who delivered before 37-week gestation with and without inflammation of chorioamnionitic membranes. A total of 57 placental samples were histologically examined for polymorphonuclear leukocyte infiltration of placental tissue for evidence of chorioamnionitis, and by type-specific nucleic acid amplification for evidence of infection with one or more of the target bacteria. Demographic data were collected for each mother.

Results: Among the 57 placental samples, 42.1% had chorioamnionitis and 24.6% delivered in the second trimester of pregnancy; U. parvum, U. urealyticum, G. vaginalis, and GBS were all detected in the study with respective prevalence of 19.3%, 3.5%, 17.5%, and 15.8%; M. genitalium and M. hominis were not detected. U. parvum was significantly associated with chorioamnionitis (p = 0.02; OR 5.0; (95% CI 1.2–21.5) and was more common in women who delivered in the second (35.7%) compared to the third trimester of pregnancy (13.9%). None of the other bacteria were associated with chorioamnionitis or earlier delivery, and all G. vaginalis-positive women delivered in the third trimester of pregnancy (p = 0.04).

Conclusions: The detection of U. parvum in placental tissue was significantly associated with acute chorioamnionitis in women presenting in extreme preterm labor.

Keywords:

• Bacteria
• intra-amniotic
• PCR
• placenta
• pregnancy
• prematurity
• trimester
• Ureaplasma

Acknowledgements

We are indebted to the permission of the mothers involved and their consent to take part in the study.

Disclosure of interest

All specimens were collected with informed consent under ethics approval from Office for Research Ethics Committees Northern Ireland (ORECNI) REC reference number: 07/NIR02/144. Date of approval: 22 February 2008.