Microbial invasion and cytokine response in amniotic fluid in a Swedish population of women in preterm labor

Abstract

Background. Previous studies indicate an association between intra-amniotic microbial invasion and/or inflammation and spontaneous preterm birth, but there is a limited amount of data available from Europe. The aim of this study was to investigate the occurrence of intra-amniotic microorganisms and cytokines (interleukin-6 and interleukin-8) in a Swedish population of women in preterm labor and their correlation with preterm birth. Methods. Amniotic fluid was retrieved transabdominally from 61 patients in preterm labor before 34 weeks of gestation. Polymerase chain reaction analyses for Ureaplasma urealyticum and Mycoplasma hominis and culture for aerobic and anaerobic bacteria were performed. Interleukin-6 and interleukin-8 were analyzed with enzyme-linked immunosorbent assay. Results. Microorganisms in amniotic fluid were detected in 10 patients (16%). Patients with detected bacteria in the amniotic fluid had significantly higher levels of interleukin-6 and interleukin-8. There was also an association between interleukin-6/-8, the amniocentesisdelivery interval ( 7 days) and preterm birth (<34 weeks). An amniotic fluid concentration of interleukin-6 ! 1.5 ng/mL or interleukin-8 ! 1.3 ng/mL was associated with an increased risk of delivery within 7 days (interleukin-6: relative risk 7.3; 95% confidence interval: 2.8-19; sensitivity 83%, specificity 87%; interleukin-8: relative risk 14, 95% confidence interval: 3.6-55, sensitivity 91%, specificity 87%). Conclusions. The occurrence of intra-amniotic microbial invasion and inflammation in this population of Swedish women in preterm labor was similar to data reported from populations with a higher incidence of preterm delivery. Amniotic interleukin-6 and interleukin-8 correlated with the presence of microorganisms and with preterm birth.

Microbial invasion and cytokine response in amniotic fluid in a Swedish population of women with preterm prelabor rupture of membranes

“…In our current study we found that nearly 53% of the women with pPROM leading to PTB (< 34 weeks of gestation) had an elevated IL‐6 level (≥ 0.80 ng/ml) compared to 31% of those that delivered ≥ 34 weeks. Our data agree with the fact that intra‐amniotic IL‐6 is one of the best predictors of preterm delivery (13) even if the sensitivity and specificity are not as high as in PTL patients (11). It has previously been shown that IL‐6 is not as good a predictor of microbial invasion of the AF in pPROM as in PTL patients, and microbial invasion of the AF is related to a short amniocentesis–delivery interval (19).…”

“…It has previously been shown that IL‐6 is not as good a predictor of microbial invasion of the AF in pPROM as in PTL patients, and microbial invasion of the AF is related to a short amniocentesis–delivery interval (19). We also found that the alpha chemokine IL‐8, which induces neutrophil attractant and activating responses, was highly expressed in the AF with pPROM but did not have as high a sensitivity and specificity as in the PTL group (11). This difference in prediction of PTB between the PTL and pPROM groups is not surprising, as different mechanisms appear to be important in pPROM compared to PTL (32).…”

Impact of microbial invasion of amniotic cavity and the type of microorganisms on short‐term neonatal outcome in women with preterm labor and intact membranes

“…Table describes demographic data and pregnancy outcomes among the three groups. As expected , the amniotic fluid IL‐6 level was higher, glucose was lower and gestational age at delivery was earlier in women with MIAC regardless of the microorganism isolated. However, gestational age at admission was earlier, and maternal CRP and WBC levels, rate of preterm delivery at <24.0 weeks and the occurrence of clinical chorioamnionitis were significantly higher in the group with MIAC than other microorganisms.…”

“…Microbial invasion of the amniotic cavity (MIAC) is a subclinical stage of infection involved in the etiopathology of PTL mainly at earlier gestational ages.…”

Non-infected preterm parturition is related to increased concentrations of IL-6, IL-8 and MCP-1 in human cervix

“…Preterm labour in correlation with infection is extensively studied. A significant cytokine increase is seen in gestational membranes, amniotic and cervicovaginal fluid in infected preterm labour [3,21,38-40]. In our study, none of the women showed clinical or laboratory signs of infection before or after labour.…”