Elevated concentrations of interleukin-6 in intra-amniotic infection with Ureaplasma urealyticum in asymptomatic women during genetic amniocentesis.
BACKGROUND
Intra-amniotic infection is an important cause of preterm delivery and interleukin-6 (IL-6) determination was recently applied for identification of microbial invasion of the amniotic cavity. Our aim was to determine the levels of IL-6 in culture-positive amniotic fluids at genetic amniocentesis and to evaluate their significance in relation to pregnancy outcome.


METHODS
Seven culture-positive and 23 culture-negative amniotic fluids, obtained at 17-19 weeks of gestation, were analyzed for IL-6 levels by an immunoassay (ELISA). Pregnancy outcomes of all 30 women were obtained from the medical charts.


RESULTS
The mean level of IL-6 in the culture-negative amniotic fluids was 78+/-206 pg/ml. Among the seven culture-positive, high levels of IL-6 were found only in three amniotic fluids that were culture-positive for Ureaplasma urealyticum (1834, 1342 and 2832 pg/ml). Low levels of IL-6, ranging from zero to 60 pg/ml, were found in four AFs that were culture-positive for Staphylococcus epidermidis (n=3) and Bacillus Gram-positive (n= 1). Adverse pregnancy outcome occurred in the three women who had intra-amniotic infection with U. urealyticum accompanied by high levels of IL-6 (two fetal loss and one preterm delivery at 28 weeks of gestation). The four women with culture-positive but IL-6 negative amniotic fluids, had normal pregnancy outcome and term delivery. Two of the 23 women with culture-negative had preterm delivery, one with high (1000 pg/ml) and one with low (80 pg/ml) levels of IL-6.


CONCLUSIONS
High levels of IL-6 are suggestive of a genuine intra-amniotic infection with urea-plasmas resulting in adverse pregnancy outcome, while culture-positive amniotic fluids with normal IL-6 levels, may suggest a state of contamination.
D000649:Amniocentesis; D000653:Amniotic Fluid / Q000737:chemistry* / Q000382:microbiology*; D001407:Bacillus / Q000302:isolation & purification; D002821:Chorioamnionitis / Q000150:complications / Q000175:diagnosis* / Q000382:microbiology; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D005313:Fetal Death / Q000209:etiology; D005820:Genetic Testing; D006801:Humans; D015850:Interleukin-6 / Q000032:analysis*; D007752:Obstetric Labor, Premature / Q000209:etiology; D011247:Pregnancy; D013212:Staphylococcus epidermidis / Q000302:isolation & purification; D016869:Ureaplasma Infections / Q000150:complications / Q000175:diagnosis*; D016990:Ureaplasma urealyticum / Q000302:isolation & purification