Mycoplasmas Frequently Cause Congenital Fetal Infection

Mycoplasmas are surface parasites of the human respiratory and urogenital tracts. They are spherical to filamentous cells with no cell walls. Twenty-three percent of neonates born between 23 and 32 weeks of gestation were found to have positive umbilical blood cultures for two genital mycoplasmas--Ureaplasma urealyticum and Mycoplasma hominis.

Although these two mycoplasmas are found in 80% of vaginal and cervical fluids, infants are not generally screened for these infections. The finding that about one-quarter of early preterm infants is already infected at birth is important for reducing adverse outcomes. These newborns had a higher incidence of neonatal systemic inflammatory response syndrome (SIRS), higher incidence of bronchopulmonary dysplasia (BPD), higher serum concentrations of interleukin (IL)-6, and more evidence of placental inflammation than those with negative cultures. It was found that the earlier the gestational age at delivery, the higher the rate of a positive umbilical cord blood culture.

The study was performed by the Alabama Preterm Birth Study (USA), and included 457 consecutive deliveries of infants born at 23-32 weeks' gestation from 1996 to 2001. It focused on a subset of 351 women/infant pairs in the population who had umbilical cord blood cultures for U. urealyticum and M. hominis.

Robert Goldenberg, M.D., professor, department of obstetrics and gynecology, Drexel University College of Medicine (Philadelphia, PA, USA) stated, "Given the frequency of these infections and their association with SIRS and [probably] with BPD, it seems reasonable to determine if infants in these categories would benefit from routine culture for U. urealyticum and/or M. hominis and subsequent treatment with an antibiotic effective against these organisms. Similarly, we question whether treatment of women likely to deliver an early gestational age infant with an antibiotic effective against these organisms might reduce subsequent neonatal morbidity and mortality.”

The study appeared in the January 2008 issue of the American Journal of Obstetrics & Gynecology. In an accompanying editorial, professors Roberto Romero, M.D., form the Center of Molecular Medicine, Wayne State University (Detroit, MI, USA) and Thomas J. Garite, from the University of California (Irvine, CA, USA) wrote, "The initial uncertainties of whether genital mycoplasmas can cause fetal/neonatal disease are disappearing in light of the accumulating evidence that these microorganisms have been implicated in neonatal sepsis, pneumonia, meningitis, and brain damage. Moreover, colonization of the neonatal respiratory tract with these organisms is a risk factor for chronic lung disease. The detection of genital mycoplasmas is not part of routine clinical practice in obstetrics and neonatology. Similarly, standard treatment for suspected neonatal sepsis does not include antibiotics effective against these microorganisms.”

Editor's note: certain species of U. urealyticum have now been classified as U. parvum, a new species.


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Drexel University College of Medicine
Wayne State University
University of California, Irvine