Oral Bacteria Linked to Uterine Infections and Preterm Birth
Oral Bacteria Linked to Uterine Infections and Preterm Birth
By Jeff Minerd, MedPage Today Staff Writer
Reviewed by Zalman S. Agus, MD; Emeritus Professor at the University of Pennsylvania School of Medicine.
April 06, 2006
Explain to patients that while suggestive, the study's findings do not support routine analysis of pregnant women's oral or vaginal flora to identify those who may be at risk for uterine infection.
Review
CLEVELAND, April 6 - The first hard evidence has been uncovered that bacteria in the mouth may find their way to the uterus, causing uterine infections that can lead to preterm birth in pregnant women.
A newly discovered and as yet unnamed species of the bacterium genus Bergeyella was found in the mouth and amniotic fluid of a woman with a uterine infection who gave birth prematurely (24 weeks), reported microbiologist Yiping W. Han, Ph.D., of Case Western Reserve here.
However, the bacterium was not detected in a vaginal swab, as might be expected. The finding confirmed what some scientists have suspected, that intrauterine infections don't always "ascend" from the genital tract but can "descend" from the oral cavity, Dr. Han and colleagues said in the April issue of the Journal of Clinical Microbiology.
The study included 19 pregnant women undergoing transabdominal amniocentesis because of preterm labor or threatened preterm labor. Amniotic fluid, blood samples, vaginal swabs, and oral swabs were collected from each woman and analyzed for bacterial DNA via polymerase chain reaction (PCR) and nucleotide sequencing.
The species of Bergeyella was detected in the mouths of all 14 women tested, but in the amniotic fluid of only one patient.
This woman had been diagnosed with a uterine infection based on an elevated white blood cell count and a low glucose level in the amniotic fluid. She went into labor, induced because of the infection, and delivered her baby at 24 weeks' gestation. Subsequent analysis of her placenta revealed severe and diffused chorioamnionitis and fetal vasculitis involving the umbilical cord and chorionic plate, which was the presumed cause of her preterm labor.
"Intrauterine infection with Bergeyella has never been reported before. Where could the bacteria come from?" the investigators asked. Because the bacteria were not detected in the vaginal tract, the investigators hypothesized they were transmitted to the uterus from the mouth via the bloodstream.
The bacteria were not detected in the patient's blood, but they had likely been cleared from the blood by the immune system before they could be detected, Dr. Han said.
Although periodontal disease has been implicated in preterm birth, the patient showed no evidence of periodontal disease, the researchers noted.
"The study is an eye-opener," Dr. Han said, "It shows that oral bacteria can get into the uterus."
The study also suggested that more than the usual bacterial suspects may be responsible for uterine infection and resulting preterm birth, Dr. Han added. The usual suspects are known vaginal flora such as Ureaplasma urealyticum or Mycoplasma hominis. But Bergeyella, a little-known, rod-shaped, Gram-negative bacteria associated with dog and cat bite wounds, had not been thought to be an important component of the oral or vaginal flora.
One reason Bergeyella may have been overlooked previously is that it is difficult to grow in culture. As much as 60% to 70% of oral bacteria can not be detected by growing on culture. The current study detected Bergeyella because it used PCR amplification of bacterial DNA rather than traditional culturing techniques, Dr. Han said.
While suggestive, the study's findings do not yet support routine analysis of pregnant women's oral or vaginal flora to identify those who may be at risk for uterine infection, Dr. Han said.
"That is the question we want to ask now," she said. Her research is examining whether particular components or oral or vaginal flora are associated with increased risk for uterine infection or preterm birth.
The mother and baby from the study are healthy and doing well, Dr. Han said.
Primary source: Journal of Clinical Microbiology
Source reference:
Yiping Han et al. Transmission of an uncultivated Bergeyella strain from the oral cavity to amniotic fluid in a case of preterm birth. Journal of Clinical Microbiology 2006; 44:1475-1483.
By Jeff Minerd, MedPage Today Staff Writer
Reviewed by Zalman S. Agus, MD; Emeritus Professor at the University of Pennsylvania School of Medicine.
April 06, 2006
Explain to patients that while suggestive, the study's findings do not support routine analysis of pregnant women's oral or vaginal flora to identify those who may be at risk for uterine infection.
Review
CLEVELAND, April 6 - The first hard evidence has been uncovered that bacteria in the mouth may find their way to the uterus, causing uterine infections that can lead to preterm birth in pregnant women.
A newly discovered and as yet unnamed species of the bacterium genus Bergeyella was found in the mouth and amniotic fluid of a woman with a uterine infection who gave birth prematurely (24 weeks), reported microbiologist Yiping W. Han, Ph.D., of Case Western Reserve here.
However, the bacterium was not detected in a vaginal swab, as might be expected. The finding confirmed what some scientists have suspected, that intrauterine infections don't always "ascend" from the genital tract but can "descend" from the oral cavity, Dr. Han and colleagues said in the April issue of the Journal of Clinical Microbiology.
The study included 19 pregnant women undergoing transabdominal amniocentesis because of preterm labor or threatened preterm labor. Amniotic fluid, blood samples, vaginal swabs, and oral swabs were collected from each woman and analyzed for bacterial DNA via polymerase chain reaction (PCR) and nucleotide sequencing.
The species of Bergeyella was detected in the mouths of all 14 women tested, but in the amniotic fluid of only one patient.
This woman had been diagnosed with a uterine infection based on an elevated white blood cell count and a low glucose level in the amniotic fluid. She went into labor, induced because of the infection, and delivered her baby at 24 weeks' gestation. Subsequent analysis of her placenta revealed severe and diffused chorioamnionitis and fetal vasculitis involving the umbilical cord and chorionic plate, which was the presumed cause of her preterm labor.
"Intrauterine infection with Bergeyella has never been reported before. Where could the bacteria come from?" the investigators asked. Because the bacteria were not detected in the vaginal tract, the investigators hypothesized they were transmitted to the uterus from the mouth via the bloodstream.
The bacteria were not detected in the patient's blood, but they had likely been cleared from the blood by the immune system before they could be detected, Dr. Han said.
Although periodontal disease has been implicated in preterm birth, the patient showed no evidence of periodontal disease, the researchers noted.
"The study is an eye-opener," Dr. Han said, "It shows that oral bacteria can get into the uterus."
The study also suggested that more than the usual bacterial suspects may be responsible for uterine infection and resulting preterm birth, Dr. Han added. The usual suspects are known vaginal flora such as Ureaplasma urealyticum or Mycoplasma hominis. But Bergeyella, a little-known, rod-shaped, Gram-negative bacteria associated with dog and cat bite wounds, had not been thought to be an important component of the oral or vaginal flora.
One reason Bergeyella may have been overlooked previously is that it is difficult to grow in culture. As much as 60% to 70% of oral bacteria can not be detected by growing on culture. The current study detected Bergeyella because it used PCR amplification of bacterial DNA rather than traditional culturing techniques, Dr. Han said.
While suggestive, the study's findings do not yet support routine analysis of pregnant women's oral or vaginal flora to identify those who may be at risk for uterine infection, Dr. Han said.
"That is the question we want to ask now," she said. Her research is examining whether particular components or oral or vaginal flora are associated with increased risk for uterine infection or preterm birth.
The mother and baby from the study are healthy and doing well, Dr. Han said.
Primary source: Journal of Clinical Microbiology
Source reference:
Yiping Han et al. Transmission of an uncultivated Bergeyella strain from the oral cavity to amniotic fluid in a case of preterm birth. Journal of Clinical Microbiology 2006; 44:1475-1483.
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