HIV/AIDS Research

Antibiotic treatment of chorioamnionitis may have the potential to reduce transmission of HIV from mother to fetus

Transmission of the human immunodeficiency virus (HIV) from HIV-positive mother to fetus occurs in 15 to 40 percent of cases when the mother has not been treated with preventive zidovudine (ZDV), compared with 5 to 10 percent with ZDV prophylaxis. Antibiotic treatment of inflammation/infection of placental membranes (chorioamnionitis) also may have the potential to reduce maternal-infant HIV transmission, suggests a study by the Low Birthweight Patient Outcomes Research Team (PORT), which was supported by the Agency for Health Care Policy and Research (PORT contract 290-92-0055).

In a recent article, PORT investigators point out that the mechanism(s) by which the fetus becomes infected with HIV are not known. However, preterm birth, chorioamnionitis, and prolonged rupture of membranes seem to be the strongest and most consistent obstetric risk factors for maternal-fetal HIV transmission. Chronic chorioamnionitis precedes many cases of preterm labor and spontaneous rupture of membranes, whereas acute chorioamnionitis is more common after rupture of the membranes at term.

Bacterial invasion of the uterus engenders a massive cytokine response by the macrophage-like cells of the decidua, placenta, and membranes. Women infected with HIV have high concentrations of cytokines (proteins released as part of an immune response) such as interleukin-6 in the amniotic fluid. These cytokines attract a large number of leucocytes (that may be HIV-infected) into the amniotic fluid. Fetal exposure to the HIV-infected amniotic fluid may be responsible for the high rates of transmission associated with chorioamnionitis, suggests the PORT's lead investigator, Robert L. Goldenberg, M.D., of the University of Alabama at Birmingham. Dr. Goldenberg and his colleagues theorize that perinatal HIV transmission could perhaps be reduced by antibiotic treatment with metronidazole alone or combined with other antibiotics.

More details are in "Choriodecidual inflammation: A potentially preventable cause of perinatal HIV-1 transmission?" by Dr. Goldenberg, Sten H. Vermund, M.D., Alice R. Goepfert, M.D., and William W. Andrews, Ph.D., in the December 12, 1998, issue of Lancet 352, pp. 1927-1930.

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