Previously Unidentified Bacteria May Cause Preterm Birth

A new study suggests that that previously unidentified bacteria may play a key role in intra-amniotic inflammation and ultimately preterm births. The researchers report their findings in the January 2009 issue of the Journal of Clinical Microbiology.

Intra-amniotic infection and inflammation have long been associated with preterm births, however, intra-amniotic inflammation is often detected despite the absence of infection.

Researchers attribute this partly to the inability of the current microbial culture method used in hospitals (considered the "gold standard" for identifying intra-amniotic infection) to recognize uncultivated species. In a prior study new culture-independent techniques recognized a previously unidentified oral species implicated in a case of extremely early preterm birth.

In the study amniotic fluid specimens were collected from women who experienced pregnancies complicated by preterm births as well as asymptomatic women and examined using both the "gold standard" culture method and 16S rRNA-based culture independent methods. No bacterial DNA in the amniotic fluid from the asymptomatic women was detected, however, bacterial DNA was found in all of the culture-positive samples as well as 17 percent of the culture-negative samples in the amniotic fluid from preterm birth mothers. Additional species were detected in more than half of the culture-positive group and approximately two-thirds of the species identified by the culture-independent methods were not isolated by the "gold standard" culture.

"Previously unrecognized, uncultivated, or difficult-to-cultivate species may play a key role in the initiation of preterm birth," say the researchers.

Reference: Y.W. Han, T. Shen, P. Chung, I.A. Buhimschi, C.S. Buhimschi. 2009. Uncultivated bacteria as etiologic agents of intra-amniotic inflammation leading to preterm birth. Journal of Clinical Microbiology, 47. 1: 38-47.