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Science in the News

Oral Bacterium Associated with Uncommon Stillbirth Case

February 16, 2010

In a newly published case report,1 an Asian woman’s delivery of a full-term stillbirth is attributed to intrauterine infection of Fusobacterium nucleatum, an anaerobic bacterium of the oral cavity that is also associated with periodontal disease. The woman had excessive gingival bleeding during pregnancy, and a late-stage respiratory infection may have weakened her immune system and increased the risk for transient bacteremia and possible hematogenous transmission of F. nucleatum. This tragic case report was publicized online by MSNBC,2 HealthDay News,3 and Medical News Today.4

To investigate the potential source of intrauterine infection, researchers reviewed evidence from a complete fetal autopsy and pathologic findings from the mother. Her placenta tested positive for F. nucleatum, as did the fetus’s lung and stomach. After collecting vaginal, rectal, and plaque samples (sub- and supragingival) from the mother, the research team found that the same clone of F. nucleatum, which was only present in her subgingival plaque, matched the isolate obtained from the stillborn infant.

Because F. nucleatum is not commonly found in the genital tract, the researchers speculated that the severity of the woman’s gingivitis heightened her risks for transient bacteremia, and that her oral cavity was the most likely source of F. nucleatum infection. An ascending route of infection was not considered plausible because F. nucleatum was only identified in the woman’s subgingival flora, not in samples collected from other areas. The case is described as the first published report of full-term stillbirth associated with possible transmission of oral F. nucleatum via the maternal bloodstream.

Although the source of intrauterine infections is often not known, the case report provides reasonable evidence that F. nucleatum infection transmitted hematogenously from the mother’s oral cavity to the uterus. Because the woman was otherwise healthy, without any history of gastrointestinal problems, it appears likely that pregnancy-associated gingivitis with excessive gum bleeding and her weakened immune system from the respiratory infection provided an opportunity for F. nucleatum to gain access to her vasculature and penetrate the placenta.

F. nucleatum is a periodontal pathogen that is commonly found in the oral cavity, but it is typically suppressed within minutes by a healthy immune system. However, F. nucleatum is also recognized as a prevalent species associated with adverse pregnancy outcomes (pre-term delivery in most cases).

The case report highlights the importance of maintaining optimal oral health through all stages of pregnancy. Dental evaluation of pregnant patients–and women who are considering pregnancy–should include a comprehensive medical history and, as needed, consultation with the patient’s physician or obstetrician. Pregnant women with periodontal infection or moderate to severe gingival inflammation are encouraged to visit their dentist for preventive intervention and/or treatment. A 2006 randomized controlled trial5 supports the safe provision of periodontal therapy and essential dental treatment to expectant mothers at 13 to 21 weeks’ gestation. Further research is warranted to monitor additional occurrences of anaerobic oral bacteremia in pregnancy, and to obtain more definitive evidence if future cases emerge.

Footnotes

1. Han YW, Fardini Y, Chen C, Iacampo KG, Peraino VA, Shamonki JM, Redline RW. Term stillbirth caused by oral Fusobacterium nucleatum. Obstretics & Gynecology 115(2), part 2,  February 2010.  Accessed January 30, 2010.

2. Carroll L. Mother’s gum disease linked to infant’s death. MSNBC. January 22, 2010. Accessed January 30, 2010.

3. Stillborn case linked to bleeding gums during pregnancy. HealthDay News. January 22, 2010. Accessed January 30, 2010.

4. First oral bacteria linking a mother and her stillborn baby. Medical News Today, January 23, 2010. Accessed January 30, 2010.

5. Michalowicz BS, Hodges JS, DiAngelis AJ, et al. Treatment of periodontal disease and the risk of preterm birth. N Engl J Med 2006; 355(18):1885–1894. 

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Science in the News is a service by the American Dental Association (ADA) to its members to present current information about science topics in the news. The ADA is a professional association of dentists committed to the public's oral health, ethics, science and professional advancement; leading a unified profession through initiatives in advocacy, education, research and the development of standards. As a science-based organization, the ADA's evaluation of the scientific evidence may change as more information becomes available. Your thoughts would be greatly appreciated.