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Antibiotic administration can eradicate intra-amniotic infection or intra-amniotic inflammation in a subset of patients with preterm labor and intact membranes

Published:March 27, 2019DOI:https://doi.org/10.1016/j.ajog.2019.03.018

      Background

      Intra-amniotic infection is present in 10% of patients with an episode of preterm labor, and is a risk factor for impending preterm delivery and neonatal morbidity/mortality. Intra-amniotic inflammation is often associated with intra-amniotic infection, but is sometimes present in the absence of detectable microorganisms. Antibiotic treatment of intra-amniotic infection has traditionally been considered to be ineffective. Intra-amniotic inflammation without microorganisms has a prognosis similar to that of intra-amniotic infection.

      Objective

      To determine whether antibiotics can eradicate intra-amniotic infection or intra-amniotic inflammation in a subset of patients with preterm labor and intact membranes.

      Materials and Methods

      The study population consisted of women who met the following criteria: 1) singleton gestation between 20 and 34 weeks; 2) preterm labor and intact membranes; 3) transabdominal amniocentesis performed for the evaluation of the microbiologic/inflammatory status of the amniotic cavity; 4) intra-amniotic infection and/or intra-amniotic inflammation; and 5) received antibiotic treatment that consisted of ceftriaxone, clarithromycin, and metronidazole. Follow-up amniocentesis was performed in a subset of patients. Amniotic fluid was cultured for aerobic and anaerobic bacteria and genital mycoplasmas, and polymerase chain reaction was performed for Ureaplasma spp. Intra-amniotic infection was defined as a positive amniotic fluid culture or positive polymerase chain reaction, and intra-amniotic inflammation was suspected when there was an elevated amniotic fluid white blood cell count or a positive result of a rapid test for matrix metalloproteinase-8. For this study, the final diagnosis of intra-amniotic inflammation was made by measuring the interleukin-6 concentration in stored amniotic fluid (>2.6 ng/mL). These results were not available to managing clinicians. Treatment success was defined as eradication of intra-amniotic infection and/or intra-amniotic inflammation or delivery ≥37 weeks.

      Results

      Of 62 patients with intra-amniotic infection and/or intra-amniotic inflammation, 50 received the antibiotic regimen. Of those patients, 29 were undelivered for ≥7 days and 19 underwent a follow-up amniocentesis. Microorganisms were identified by culture or polymerase chain reaction of amniotic fluid obtained at admission in 21% of patients (4/19) who had a follow-up amniocentesis, and were eradicated in 3 of the 4 patients. Resolution of intra-amniotic infection/inflammation was confirmed in 79% of patients (15/19), and 1 other patient delivered at term, although resolution of intra-amniotic inflammation could not be confirmed after a follow-up amniocentesis. Thus, resolution of intra-amniotic inflammation/infection or term delivery (treatment success) occurred in 84% of patients (16/19) who had a follow-up amniocentesis. Treatment success occurred in 32% of patients (16/50) with intra-amniotic infection/inflammation who received antibiotics. The median amniocentesis-to-delivery interval was significantly longer among women who received the combination of antibiotics than among those who did not (11.4 days vs 3.1 days: P = .04).

      Conclusion

      Eradication of intra-amniotic infection/inflammation after treatment with antibiotics was confirmed in 79% of patients with preterm labor, intact membranes, and intra-amniotic infection/inflammation who had a follow-up amniocentesis. Treatment success occurred in 84% of patients who underwent a follow-up amniocentesis and in 32% of women who received the antibiotic regimen.

      Key words

      Related editorial, page 83.
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      Why was this study conducted?

      • This study was conducted to determine whether intra-amniotic infection or intra-amniotic inflammation can be treated with antibiotics in patients with preterm labor and intact membranes.

      Key findings

      • Resolution of intra-amniotic inflammation or intra-amniotic infection was objectively demonstrated by analysis of amniotic fluid after treatment with antibiotics in 79% of patients.

      What does this add to what is known?

      • Contrary to what is widely believed, antimicrobial treatment of intra-amniotic infection or intra-amniotic inflammation can be successful in a subset of patients with preterm labor and intact membranes. These observations encourage new therapeutic alternatives and call for personalized assessment of patients with preterm labor and intact membranes to identify those who can benefit from this intervention.
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      Prevalence and clinical significance of sterile intra-amniotic inflammation in patients with preterm labor and intact membranes.
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      Clinical significance of intra-amniotic inflammation in patients with preterm labor and intact membranes.
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      However, the optimal treatment of patients with an episode of preterm labor, intact membranes, and intra-amniotic infection or intra-amniotic inflammation has not been determined. Previous reports demonstrated the eradication of microorganisms in the amniotic cavity of patients with a short cervix
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      and preterm PROM.
      • Romero R.
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      Sterile and microbial-associated intra-amniotic inflammation in preterm prelabor rupture of membranes.
      • Lee J.
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      • Kim S.M.
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      A new antibiotic regimen treats and prevents intra-amniotic inflammation/infection in patients with preterm PROM.
      A recent report suggests that a subset of patients with preterm labor and intra-amniotic infection may benefit from antibiotic administration.
      • Yoneda S.
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      We have recently reported that antibiotic treatment in patients with preterm PROM can reduce the rate of intra-amniotic infection and intra-amniotic inflammation, as well as funisitis and the fetal systemic inflammatory response, using a combination of antibiotics (ceftriaxone, clarithromycin, and metronidazole) that target microorganisms frequently isolated from the amniotic cavity in these cases.
      • Lee J.
      • Romero R.
      • Kim S.M.
      • Chaemsaithong P.
      • Yoon B.H.
      A new antibiotic regimen treats and prevents intra-amniotic inflammation/infection in patients with preterm PROM.
      • Lee J.
      • Romero R.
      • Kim S.M.
      • et al.
      A new anti-microbial combination prolongs the latency period, reduces acute histologic chorioamnionitis as well as funisitis, and improves neonatal outcomes in preterm PROM.
      The purpose of this study was to determine whether antibiotics could eradicate intra-amniotic infection or intra-amniotic inflammation without demonstrable microorganisms in patients with preterm labor and intact membranes.

      Materials and Methods

      Study design

      This is a retrospective case series study of pregnant women admitted to Seoul National University Hospital between January 2004 and March 2014 who met the following criteria: 1) singleton gestation between 20 and 34 weeks; 2) preterm labor and intact amniotic membranes determined by sterile speculum examination; 3) transabdominal amniocentesis performed for the evaluation of the microbiologic and inflammatory status of the amniotic cavity; 4) positive amniotic fluid culture or intra-amniotic inflammation; and 5) antibiotic treatment (regimen consisted of ceftriaxone, clarithromycin, and metronidazole). Follow-up amniocentesis was performed in a subset of patients at the discretion of the managing physician.
      At the Seoul National University Hospital, a transabdominal amniocentesis is routinely offered to all patients admitted with the diagnosis of preterm labor to assess the microbiologic status of the amniotic cavity and fetal lung maturity. Retrieval of amniotic fluid was performed after written informed consent was obtained. Preterm labor was diagnosed as the presence of regular uterine contractions (4 or more contractions in 20 minutes or 8 or more in 60 minutes). The Institutional Review Board of the Seoul National University Hospital approved the collection and use of these samples and clinical information for research purposes. The Seoul National University has a Federal Wide Assurance with the Office for Human Research Protection (OHRP) of the Department of Health and Human Services (DHHS) of the United States.

      Amniotic fluid analysis

      Amniotic fluid was cultured for aerobic and anaerobic bacteria as well as genital mycoplasmas. Beginning in 2007, samples were also assayed for Ureaplasma spp. by means of polymerase chain reaction (PCR) with specific primers using methods previously described.
      • Yoon B.H.
      • Romero R.
      • Lim J.H.
      • et al.
      The clinical significance of detecting Ureaplasma urealyticum by the polymerase chain reaction in the amniotic fluid of patients with preterm labor.
      An aliquot of amniotic fluid was examined in a hemocytometer chamber to determine the white blood cell count.
      • Yoon B.H.
      • Romero R.
      • Moon J.B.
      • et al.
      Clinical significance of intra-amniotic inflammation in patients with preterm labor and intact membranes.
      • Yoon B.H.
      • Yang S.H.
      • Jun J.K.
      • Park K.H.
      • Kim C.J.
      • Romero R.
      Maternal blood C-reactive protein, white blood cell count, and temperature in preterm labor: a comparison with amniotic fluid white blood cell count.
      In a subset of patients, MMP-8 concentration in amniotic fluid was measured using a commercially available enzyme-linked immunosorbent assay (ELISA) (Amersham Pharmcia Biotech, Inc, Bucks, UK) and the results were available to clinicians. Intra-amniotic inflammation was suspected when the concentration of MMP-8 in the amniotic fluid was higher than 23 ng/mL, as previously reported.
      • Shim S.S.
      • Romero R.
      • Hong J.S.
      • et al.
      Clinical significance of intra-amniotic inflammation in patients with preterm premature rupture of membranes.
      • Lee S.E.
      • Romero R.
      • Park C.W.
      • Jun J.K.
      • Yoon B.H.
      The frequency and significance of intraamniotic inflammation in patients with cervical insufficiency.
      • Park J.S.
      • Romero R.
      • Yoon B.H.
      • et al.
      The relationship between amniotic fluid matrix metalloproteinase-8 and funisitis.
      • Oh K.J.
      • Lee S.E.
      • Jung H.
      • Kim G.
      • Romero R.
      • Yoon B.H.
      Detection of ureaplasmas by the polymerase chain reaction in the amniotic fluid of patients with cervical insufficiency.
      • Kim S.M.
      • Romero R.
      • Park J.W.
      • Oh K.J.
      • Jun J.K.
      • Yoon B.H.
      The relationship between the intensity of intra-amniotic inflammation and the presence and severity of acute histologic chorioamnionitis in preterm gestation.
      • Oh K.J.
      • Kim S.M.
      • Hong J.S.
      • et al.
      Twenty-four percent of patients with clinical chorioamnionitis in preterm gestations have no evidence of either culture-proven intraamniotic infection or intraamniotic inflammation.
      Between March 2005 and December 2010, a rapid MMP-8 bedside test (MMP-8 PTD Check test, SK Pharma Co, Ltd, Kyunggi-do, Korea) was performed and used in patient management. Details of the MMP-8 rapid test have been previously described.
      • Nien J.K.
      • Yoon B.H.
      • Espinoza J.
      • et al.
      A rapid MMP-8 bedside test for the detection of intra-amniotic inflammation identifies patients at risk for imminent preterm delivery.
      • Kim S.M.
      • Romero R.
      • Lee J.
      • et al.
      About one-half of early spontaneous preterm deliveries can be identified by a rapid matrix metalloproteinase-8 (MMP-8) bedside test at the time of mid-trimester genetic amniocentesis.
      • Kim K.W.
      • Romero R.
      • Park H.S.
      • et al.
      A rapid matrix metalloproteinase-8 bedside test for the detection of intraamniotic inflammation in women with preterm premature rupture of membranes.
      • Chaemsaithong P.
      • Romero R.
      • Docheva N.
      • et al.
      Comparison of rapid MMP-8 and interleukin-6 point-of-care tests to identify intra-amniotic inflammation/infection and impending preterm delivery in patients with preterm labor and intact membranes.
      Amniotic fluid not used for diagnostic tests was centrifuged at 800 g and stored at −80°C.
      Intra-amniotic infection was defined as a positive amniotic fluid culture or positive PCR for Ureaplasma spp. For the purposes of this study, a definitive diagnosis of intra-amniotic inflammation was made when the interleukin-6 concentration of stored amniotic fluid was higher than 2.6 ng/mL.
      • Yoon B.H.
      • Romero R.
      • Moon J.B.
      • et al.
      Clinical significance of intra-amniotic inflammation in patients with preterm labor and intact membranes.
      The amniotic fluid interleukin-6 concentration was measured with a commercially available ELISA kit (R&D Systems, Minneapolis, MN) in 2017 and 2018. The sensitivity of the assay was 0.7 pg/mL. The intra- and interassay coefficients of variation were <10%. These results were not available to managing clinicians.

      Clinical management

      Intra-amniotic inflammation was suspected when there was an elevated amniotic fluid white blood cell count (defined as ≥19 cells/mm3),
      • Park J.S.
      • Romero R.
      • Yoon B.H.
      • et al.
      The relationship between amniotic fluid matrix metalloproteinase-8 and funisitis.
      a positive MMP-8 rapid test result,
      • Nien J.K.
      • Yoon B.H.
      • Espinoza J.
      • et al.
      A rapid MMP-8 bedside test for the detection of intra-amniotic inflammation identifies patients at risk for imminent preterm delivery.
      • Kim K.W.
      • Romero R.
      • Park H.S.
      • et al.
      A rapid matrix metalloproteinase-8 bedside test for the detection of intraamniotic inflammation in women with preterm premature rupture of membranes.
      • Chaemsaithong P.
      • Romero R.
      • Docheva N.
      • et al.
      Comparison of rapid MMP-8 and interleukin-6 point-of-care tests to identify intra-amniotic inflammation/infection and impending preterm delivery in patients with preterm labor and intact membranes.
      or an elevated concentration of amniotic fluid MMP-8 (>23 ng/mL) measured by ELISA.
      • Shim S.S.
      • Romero R.
      • Hong J.S.
      • et al.
      Clinical significance of intra-amniotic inflammation in patients with preterm premature rupture of membranes.
      • Lee S.E.
      • Romero R.
      • Park C.W.
      • Jun J.K.
      • Yoon B.H.
      The frequency and significance of intraamniotic inflammation in patients with cervical insufficiency.
      • Park J.S.
      • Romero R.
      • Yoon B.H.
      • et al.
      The relationship between amniotic fluid matrix metalloproteinase-8 and funisitis.
      Suspicion of intra-amniotic inflammation, isolation of microorganisms by amniotic fluid culture, or the detection of Ureaplasma nucleic acids was an indication for the administration of antibiotics. We used a combination of antimicrobial agents previously prescribed in the management of patients with preterm PROM,
      • Lee J.
      • Romero R.
      • Kim S.M.
      • Chaemsaithong P.
      • Yoon B.H.
      A new antibiotic regimen treats and prevents intra-amniotic inflammation/infection in patients with preterm PROM.
      • Lee J.
      • Romero R.
      • Kim S.M.
      • et al.
      A new anti-microbial combination prolongs the latency period, reduces acute histologic chorioamnionitis as well as funisitis, and improves neonatal outcomes in preterm PROM.
      including ceftriaxone 1 g (intravenous) every 24 hours, clarithromycin 500 mg (oral) every 12 hours, and metronidazole 500 mg (intravenous) every 8 hours. Metronidazole was administered for a maximum of 4 weeks. A follow-up amniocentesis was offered to monitor the microbiologic and inflammatory status of amniotic cavity and fetal lung maturity. The use, discontinuation, or change of antibiotic regimen or tocolytics, or the interval to follow-up amniocentesis, was left to the discretion of the treating clinicians because there was no uniformity among attending physicians about these issues. Tocolytics used were ritodrine, magnesium sulphate, or atosiban. Nonsteroidal anti-inflammatory agents, such as indomethacin, were not used as tocolytic agents. GBS screening and intrapartum treatment are not routinely performed in our institution because neonatal GBS sepsis is extremely rare in our patient population.
      • Heo J.S.
      • Shin S.H.
      • Jung Y.H.
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      • Lee S.M.
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      • Kim K.S.
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      Definition of treatment success in this study

      Treatment success was defined as 1) eradication of intra-amniotic infection or intra-amniotic inflammation; or 2) delivery at or after 37 weeks of gestation.

      Diagnosis of acute histologic chorioamnionitis and clinical chorioamnionitis

      Acute histologic chorioamnionitis was diagnosed in the presence of acute inflammatory changes in tissue samples collected from the amnion and chorion-decidua.
      • Yoon B.H.
      • Romero R.
      • Kim C.J.
      • et al.
      Amniotic fluid interleukin-6: a sensitive test for antenatal diagnosis of acute inflammatory lesions of preterm placenta and prediction of perinatal morbidity.
      Funisitis was diagnosed in the presence of neutrophil infiltration into the umbilical vessel walls or Wharton’s jelly.
      • Shim S.S.
      • Romero R.
      • Hong J.S.
      • et al.
      Clinical significance of intra-amniotic inflammation in patients with preterm premature rupture of membranes.
      • Lee S.E.
      • Romero R.
      • Park C.W.
      • Jun J.K.
      • Yoon B.H.
      The frequency and significance of intraamniotic inflammation in patients with cervical insufficiency.
      • Park J.S.
      • Romero R.
      • Yoon B.H.
      • et al.
      The relationship between amniotic fluid matrix metalloproteinase-8 and funisitis.
      • Maymon E.
      • Romero R.
      • Pacora P.
      • et al.
      Human neutrophil collagenase (matrix metalloproteinase 8) in parturition, premature rupture of the membranes, and intrauterine infection.
      • Pacora P.
      • Chaiworapongsa T.
      • Maymon E.
      • et al.
      Funisitis and chorionic vasculitis: the histological counterpart of the fetal inflammatory response syndrome.
      • Yoon B.H.
      • Romero R.
      • Shim J.Y.
      • Shim S.S.
      • Kim C.J.
      • Jun J.K.
      C-reactive protein in umbilical cord blood: a simple and widely available clinical method to assess the risk of amniotic fluid infection and funisitis.
      • Lee S.E.
      • Romero R.
      • Kim C.J.
      • Shim S.S.
      • Yoon B.H.
      Funisitis in term pregnancy is associated with microbial invasion of the amniotic cavity and intra-amniotic inflammation.
      Clinical chorioamnionitis was diagnosed by the presence of maternal fever (temperature >37.8°C) accompanied by 2 or more of the following criteria: 1) maternal tachycardia (heart rate >100 beats/min); 2) uterine tenderness; 3) foul-smelling amniotic fluid; 4) fetal tachycardia (heart rate >160 beats/min); and 5) maternal leukocytosis (leukocyte count >15,000 cells/mm³).
      • Gibbs R.S.
      • Blanco J.D.
      • St Clair P.J.
      • Castaneda Y.S.
      Quantitative bacteriology of amniotic fluid from women with clinical intraamniotic infection at term.
      The limitations of these criteria in the identification of intra-amniotic infection have been recently described.
      • Lee J.
      • Romero R.
      • Kim S.M.
      • Chaemsaithong P.
      • Yoon B.H.
      A new antibiotic regimen treats and prevents intra-amniotic inflammation/infection in patients with preterm PROM.
      • Oh K.J.
      • Kim S.M.
      • Hong J.S.
      • et al.
      Twenty-four percent of patients with clinical chorioamnionitis in preterm gestations have no evidence of either culture-proven intraamniotic infection or intraamniotic inflammation.
      • Romero R.
      • Chaemsaithong P.
      • Korzeniewski S.J.
      • et al.
      Clinical chorioamnionitis at term II: the intra-amniotic inflammatory response.
      • Romero R.
      • Chaemsaithong P.
      • Docheva N.
      • et al.
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      • Sung J.H.
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      • Oh S.Y.
      • Roh C.R.
      • Kim J.H.
      Revisiting the diagnostic criteria of clinical chorioamnionitis in preterm birth.
      The criteria for the diagnosis of neonatal morbidity can be found in Supplementary Material S1.

      Statistical analysis

      Continuous variables were compared between 2 groups with the Mann−Whitney U test. Proportions were compared with a Fisher's exact test. The amniocentesis-to-delivery interval was compared by using the generalized Wilcoxon test for survival analysis. A P value <.05 was considered statistically significant. Statistical analyses were performed using SPSS software (Version 22; SPSS Inc, Chicago, IL).

      Results

      Characteristics of study population

      Figure 1 shows a flow diagram of patients included in this study. A total of 62 patients with intra-amniotic infection and/or intra-amniotic inflammation were identified. A positive amniotic fluid culture was present in 11 patients; Ureaplasma spp. was detected by the PCR method in 8 patients; and intra-amniotic inflammation was identified in 51 patients with an amniotic fluid culture negative for microorganisms. Bacteria identified by culture included Ureaplasma urealyticum (n = 9), Mycoplasma hominis (n = 2), and 1 isolate each of Streptococcus anginosus and Gardnerella vaginalis.
      Figure thumbnail gr1
      Figure 1Flow diagram of the study population
      Yoon et al. Antibiotics in preterm labor with intra-amniotic inflammation. Am J Obstet Gynecol 2019.
      Of 62 patients with intra-amniotic infection and/or intra-amniotic inflammation, 50 received the combination of ceftriaxone, clarithromycin, and metronidazole. The remaining 12 patients did not receive this antibiotic regimen (11 patients did not receive any antibiotics; 1 patient received an alternative regimen, consisting of ceftriaxone, azithromycin, and metronidazole). Of the 11 patients who did not receive any antibiotics, 1 patient had an amniotic fluid culture positive for Ureaplasma urealyticum, and antibiotics were not administered because of rapid progression of preterm labor to delivery.
      The lack of antibiotic administration in the other 10 patients occurred for the following reasons: 1) intra-amniotic infection/inflammation was not suspected because the patients had a low amniotic fluid white blood cell count when the MMP-8 rapid test was not available (n = 4); however, intra-amniotic inflammation was diagnosed by elevated concentrations of interleukin-6 retrospectively; 2) the managing clinician preferred to rely on the results of the amniotic fluid white blood cell count rather than on those of the rapid MMP-8 test (n = 2); 3) rapid progression of labor (n = 2); 4) declined antibiotic treatment (n = 1); and 5) transfer to another hospital because of unavailability of a neonatal intensive care bed (n = 1).
      Table 1 compares the characteristics and outcomes of patients who received the antibiotic regimen to those of patients who did not. There were no significant differences between the study groups in maternal age, cerclage use, gestational age at amniocentesis, interleukin-6 concentration, frequency of a positive amniotic fluid culture, use of tocolytics and antenatal corticosteroids, delivery within 7 and 14 days of amniocentesis, delivery at <30, <34 and ≥37 weeks, clinical and acute histologic chorioamnionitis, and funisitis (P > 0.1 for each). Patients who received the antibiotic regimen had a significantly higher median amniotic fluid white blood cell count (79 cells/mm3 vs 3 cells/mm3), longer median amniocentesis-to-delivery interval (11.4 days vs 3.1 days), and lower rate of delivery within 4 weeks of amniocentesis (58% vs 91.7%) than those in whom the antibiotic regimen was not used (P < .05 for each).
      Table 1Clinical characteristics and outcomes of patients who did vs did not use the regimen of antibiotics consisting of ceftriaxone, clarithromycin, and metronidazole
      Use of ceftriaxone, clarithromycin, and metronidazole (n = 50)No antibiotics or use of other antibiotics (n = 12)P value
      Maternal age (y)31 (29–34)34 (31–36).12
      Nulliparity (%)62.0% (31/50)25.0% (3/12).027
      Cerclage before onset of preterm labor12.0% (6/50)8.3% (1/12).99
      Cerclage after onset of preterm labor and preterm labor stopped4.0% (2/50)8.3% (1/12).48
      Initial amniocentesis
       Gestational age at amniocentesis (wk)25.4 (22.1–27.5)25.7 (22.6–28.6).63
       Positive amniotic fluid culture (%)20.0% (10/50)9.1% (1/12).68
       Positive amniotic fluid PCR for Ureaplasma spp.21.2% (7/33)11.1% (1/9).66
       Amniotic fluid WBC count (cells/mm3)79 (2–860)3 (0–65).048
       Amniotic fluid WBC count (≥19 cells/mm3)58.3% (28/48)25.0% (3/12).054
       Amniotic fluid interleukin-6 (ng/mL)18.2 (4.1–43.0)7.8 (3.2–16.9).12
       Amniotic fluid interleukin-6 (>2.6 ng/mL)100% (49/49)100% (12/12)>.99
       Cervical dilatation >3 cm (%)10.0% (5/50)16.7% (2/12).61
      Use of tocolytics (%)98.0% (49/50)91.7% (11/12).35
      Antenatal corticosteroids administration (%)62.0% (31/50)58.3% (7/12)>.99
      Gestational age at delivery (wk)28.9 (25.5–33.9)27.3 (23.4–31.7).29
      Interval between amniocentesis to delivery (days)11.4 (2.8–57.0)3.1 (0.3–17.8).04
      The amniocentesis-to-delivery interval was compared by using the generalized Wilcoxon test for survival analysis.
      Delivery within 7 days of amniocentesis42.0% (21/50)58.3% (7/12).35
      Delivery within 14 days of amniocentesis52.0% (26/50)67% (8/12).52
      Delivery within 4 wk of amniocentesis58.0% (29/50)91.7% (11/12).042
      Delivery before 30 wk
      Patients who underwent amniocentesis at or beyond 30 wk were excluded from the analysis
      57.4% (27/47)81.8% (9/11).18
      Delivery before 34 wk76.0% (38/50)91.7% (11/12).43
      Delivery at term (≥37 wk)8.0% (4/50)8.3% (1/12)>.99
      Clinical chorioamnionitis12.0% (6/50)0% (0/12).59
      Acute histologic chorioamnionitis69.2% (27/39)88.9% (8/9).41
      Funisitis30.8% (12/39)22.2% (2/9)>.99
      Data are median (interquartile range) or percentage (n/N).
      PCR, polymerase chain reaction; WBC, white blood cell.
      Yoon et al. Antibiotics in preterm labor with intra-amniotic inflammation. Am J Obstet Gynecol 2019.
      a Patients who underwent amniocentesis at or beyond 30 wk were excluded from the analysis
      b The amniocentesis-to-delivery interval was compared by using the generalized Wilcoxon test for survival analysis.
      Of 50 patients treated with the antibiotic regimen, 29 remained undelivered for at least 1 week (Figure 1). Microorganisms identified in the amniotic fluid of 29 patients undelivered for at least 1 week included Ureaplasma urealyticum (n = 4) and Mycoplasma hominis (n = 1). One patient had a mixed infection of Ureaplasma urealyticum and Mycoplasma hominis. Microorganisms identified in the amniotic fluid of 21 patients who delivered within 7 days of amniocentesis included Ureaplasma urealyticum (n = 4), and 1 isolate each of Mycoplasma hominis, Streptococcus anginosus, and Gardnerella vaginalis. One patient had a mixed infection of Ureaplasma urealyticum and Mycoplasma hominis.
      Table 2 compares the characteristics and outcomes of patients who delivered within 7 days of amniocentesis and those who were undelivered for at least 7 days. There were no significant differences in the median gestational age at amniocentesis and the frequency of a positive amniotic fluid culture for microorganisms between the 2 groups (P > .1 for each). Patients who remained undelivered for at least 1 week had a significantly lower median concentration of amniotic fluid interleukin-6 and white blood cell count than those who delivered before 1 week (P < .005 for both).
      Table 2Characteristics and outcomes of patients delivered within 7 days of amniocentesis and those who were undelivered for at least 7 days
      Delivery before 1 week (n = 21)Undelivered for ≥ 1 week (n = 29)P value
      Maternal age (y)33 (30–36)30 (28–33).07
      Nulliparity (%)47.6% (10/21)72.4% (21/29).09
      Initial amniocentesis
       Gestational age at amniocentesis (wk)26.4 (22.6–28.4)24.3 (21.9–26.9).13
       Positive amniotic fluid culture (%)28.6% (6/21)13.8% (4/29).29
       Positive amniotic fluid PCR for Ureaplasma spp.14.3% (2/14)26.3% (5/19).67
       Amniotic fluid WBC count (cells/mm3)725 (94 to >1000)5 (1–100).002
       Amniotic fluid WBC count (≥ 19 cells/mm3)81.0% (17/21)40.7% (11/27).008
       Amniotic fluid interleukin-6 (ng/mL)28.2 (14.0–46.5)10.3 (3.4–21.8).001
       Amniotic fluid interleukin-6 (>2.6 ng/mL)100% (21/21)100% (28/28)>.99
       Cervical dilatation > 3 cm (%)14.3% (3/21)6.9% (2/29).64
      Use of tocolytics (%)95.2% (20/21)100% (29/29).42
      Antenatal corticosteroids administration (%)52.4% (11/21)69.0% (20/29).26
      Gestational age at delivery (wk)26.6 (22.9–28.7)33.1 (27.3–34.9)<.001
      Delivery within 14 days of amniocentesis100% (21/21)17.2% (5/29)<.001
      Delivery within 4 wk of amniocentesis100% (21/21)27.6% (8/29)<.001
      Delivery before 30 wk
      Patients who underwent amniocentesis at or beyond 30 weeks were excluded from the analysis.
      94.7% (18/19)32.1% (9/28)<.001
      Delivery before 34 wk100% (21/21)58.6% (17/29).001
      Delivery at term (≥37 wk)0% (0/21)13.8% (4/29).13
      Clinical chorioamnionitis23.8% (5/21)3.4% (1/29).07
      Acute histologic chorioamnionitis81.3% (13/16)60.9% (14/12).29
      Funisitis37.5% (6/16)26.1% (6/23).50
      Data are median (interquartile range) or percentage (n/N).
      PCR, polymerase chain reaction; WBC, white blood cell.
      Yoon et al. Antibiotics in preterm labor with intra-amniotic inflammation. Am J Obstet Gynecol 2019.
      a Patients who underwent amniocentesis at or beyond 30 weeks were excluded from the analysis.
      Of 29 patients undelivered for ≥7 days, 10 did not have a follow-up amniocentesis (5 declined the procedure, 2 had severe oligohydramnios due to rupture of membranes, 2 were transferred to another hospital, and for 1 patient, the treating physician did not recommend the procedure). The remaining 19 patients had a follow-up amniocentesis to determine whether (1) intra-amniotic infection had been eradicated, (2) intra-amniotic inflammation was being treated, and (3) antibiotic treatment should be continued or stopped. Generally, antibiotics were discontinued if patients had a negative MMP-8 test result or if the amniotic fluid white blood cell count became normal. However, the final decision was made by the attending obstetrician.
      There were no significant differences in the median gestational age at amniocentesis, amniotic fluid interleukin-6 concentration and white blood cell count, and the frequency of a positive amniotic fluid culture between patients who were undelivered for at least 1 week and had a follow-up amniocentesis and those who had not (P > .1 for each). Patients who did not have a follow-up amniocentesis delivered significantly earlier than those who had a follow-up amniocentesis (27.3 weeks [interquartile range, 25.0–33.9 weeks] vs 34.1 weeks [interquartile range, 31.7–35.6 weeks]; P < .05).

      Treatment success with antibiotics in this study

      Of the 19 patients who had a follow-up amniocentesis, intra-amniotic inflammation was successfully resolved in 15, and intra-amniotic infection was eradicated in 3 (1 patient with a positive culture and a positive PCR result for Ureaplasma spp., and 2 with a negative culture but a positive PCR result for Ureaplasma spp.). All patients with intra-amniotic infection also had intra-amniotic inflammation.
      Microbiologic or biochemical evidence of successful treatment was demonstrated in 79% (15/19). One patient who did not have confirmation of eradication of intra-amniotic infection/inflammation at the follow-up amniocentesis delivered at term. None of the 10 patients who did not have a follow-up amniocentesis delivered at term. Thus, treatment success of antibiotics (defined as eradication of intra-amniotic infection/inflammation or delivery ≥37 weeks of gestation) occurred in 84% of patients (16/19) who had a follow-up amniocentesis and was possible in at least 32% of patients (16/50) with intra-amniotic infection/inflammation who received the antimicrobial agents.

      Clinical outcome of patients treated with antimicrobial agents who had a follow-up amniocentesis

      Table 3 shows the details and Table 4 summarizes the characteristics and outcomes of 19 patients who were treated with the antimicrobial agents and had a follow-up amniocentesis. A detailed description of each patient can be found in Supplementary Material S2.
      Table 3Details of presentations of initial amniocentesis, and outcomes of patients who were treated with antibiotics (ceftriaxone, clarithromycin, and metronidazole) and had follow-up amniocentesis


      Case no.
      Gestational age, wkInitial amniocentesisInterval between initial amniocentesis and resolution (days)
      The first amniocentesis without evidence of intra-amniotic infection/inflammation.
      Birth weight (gm)Steroid for fetal lung maturity (wk)Acute histologic chorioamnionitis/funisitisNeonatal outcomes
      Amnio-centesisDeliveryCulturePCR for Ureaplasma spp.Interleukin-6 (ng/mL)WBC count (cells/mm3)MMP-8 rapid test
      Group A:Resolution confirmed and delivered after 34 weeks of gestation
       125.135.6NegPos5.011Pos28Unknown25.3N/ASurvival without morbidity
       222.738.3NegN/A33.4100Pos14262022.9–/–Survival without morbidity
       326.040.1NegN/A2.75Pos7386026.0–/–Survival without morbidity
       429.634.1NegN/A2.70Pos7220033.3–/–Survival without morbidity
       522.938.0NegNeg2.85Pos382850–/–Survival without morbidity
       626.734.7NegN/A4.10Pos7261026.3+/–Survival without morbidity
       727.635.4NegNeg4.01Pos10unknownN/ASurvival without morbidity
       820.934.7NegNeg3.31Pos672040+/–Survival without morbidity
       925.635.0NegNeg3.625N/A482290–/–Survival without morbidity
      Group B:Resolution confirmed but delivered before 34 weeks of gestation
       1028.431.7NegPos42.6720N/A13184028.4+/–Survival without morbidity
       1124.032.6NegNeg2.92N/A30199029.7+/–Survival without morbidity
       1225.430.4NegN/A2.60Pos15140024.0+/+Survival without morbidity
       1321.033.3NegNeg51.5105Pos22180027.9–/–Survived and diagnosed as BPD
       1421.029.6PosPos4.80N/A30164029.4+/–Survival without morbidity
       1520.125.4NegNeg11.116Pos1570025.4+/+Shortly died (5 hours from birth)
      Group C:Resolution not confirmed but delivered after 37 weeks of gestation
       1621.638.0NegNeg19.42N/A2760–/–Survival without morbidity
      Group D:Resolution not confirmed and delivered before 34 weeks of gestation
       1731.432.9NegNeg22.0100Pos171030.9+/+Survival without morbidity
       1826.432.6PosN/A18.250Pos2060+/–Survival without morbidity
       1922.123.6NegN/A23.854Pos620+/–Survived and diagnosed as RDS, BPD, IVH, PVL
      BPD, bronchopulmonary dysplasia; IVH, intraventricular hemorrhage; MMP-8, matrix metalloproteinase-8; N/A, not assessed; Neg, negative result; PCR, polymerase chain reaction; Pos, positive result; RDS, respiratory distress syndrome; PVL, periventricular leukomalacia.
      Yoon et al. Antibiotics in preterm labor with intra-amniotic inflammation. Am J Obstet Gynecol 2019.
      a The first amniocentesis without evidence of intra-amniotic infection/inflammation.
      Table 4Characteristics and outcomes of 19 patients who were treated with antibiotics (ceftriaxone, clarithromycin, and metronidazole) and had follow-up amniocentesis
      Resolution of intra-amniotic inflammation
      Confirmed (n = 15)Not confirmed (n = 4)
      Group A:

      Delivery at or after 34 wk (n = 9)
      Group B:

      Delivery before 34 wk (n = 6)
      Group C:

      Delivery at or after 34 wk (n = 1)
      Group D:

      Delivery before 34 wk (n = 3)
      Nulliparity88.9% (8/9)66.7% (4/6)0% (0/1)66.6% (2/3)
      History of preterm delivery0% (0/9)16.7% (1/6)0% (0/1)0% (0/3)
      Progesterone treatment0000
      Cerclage before onset of preterm labor11.1% (1/9)16.7% (1/6)0% (0/1)33.3% (1/3)
      Cerclage after onset of preterm labor and labor stopped0% (0/9)16.7% (1/6)0% (0/1)0% (0/1)
      Initial amniocentesis
       Gestational age at amniocentesis25.6 (22.9–26.7)22.5 (21.0–25.4)21.626.4 (22.1–31.4)
       Positive amniotic fluid culture (%)0% (0/9)16.7% (1/6)0% (0/1)33.3% (1/3)
       Positive amniotic fluid PCR for Ureaplasma spp.20% (1/5)40% (2/5)0% (0/1)0% (0/1)
       Amniotic fluid WBC count (cells/mm3)5 (1–11)16 (2–105)254 (50–100)
      P < .05 compared to Group A
       Positive MMP-8 rapid test87.5% (7/8)100% (3/3)0% (0/0)100% (3/3)
       Amniotic fluid interleukin-6 (ng/mL)3.56 (2.79–4.09)7.02 (2.6–42.6)19.4021.97 (18.22–23.84)
      Days from initial amniocentesis to resolution14 (7–38)18 (13–22)N/AN/A
      Duration of new antibiotic regimen use (days)
      Some patients restarted antibiotic administration because they developed preterm rupture of membranes or preterm labor and intra-amniotic infection/inflammation after the discontinuation of antibiotics as intra-amniotic infection/inflammation resolved and preterm labor stopped. This duration was not included in this analysis
      21 (14–25)25.5 (21–31)1410 (10–33)
      Number of amniocenteses4 (4–4)3.5 (3–4)22 (2–3)
      Gestational age at delivery (wk)35.4 (34.7–38.0)31.1 (29.6–32.6)
      P < .05 compared to Group A
      38.032.6 (23.6–32.9)
      P < .05 compared to Group A
      Days from initial amniocentesis to delivery73 (56–103)48 (32–66)11510 (10–43)
      P < .05 compared to Group A
      Delivery within 14 days of amniocentesis0% (0/9)0% (0/6)0% (0/1)66.7% (2/3)
      P < .05 compared to Group A
      Delivery within 4 wk of amniocentesis0% (0/9)16.7% (1/6)0% (0/1)66.7% (2/3)
      P < .05 compared to Group A
      Delivery before 30 wk0% (0/9)33.3% (2/6)0% (0/1)50.0% (1/2)
      Patient case who underwent amniocentesis at or beyond 30 weeks was excluded from the analysis.
      Delivery before 34 wk0% (0/9)100% (6/6)
      P < .05 compared to Group A
      0% (0/1)100% (3/3)
      P < .05 compared to Group A
      Delivery at term (≥37 wk)66.7% (6/9)0% (0/6)100% (1/1)0% (0/3)
      Birth weight (g)2610 (2200–2850)1720 (1225–1878)
      P < .05 compared to Group A
      27601710 (620–2060)
      P < .05 compared to Group A
      Clinical chorioamnionitis0% (0/9)0% (0/6)0% (0/1)0% (0/3)
      Acute histologic chorioamnionitis28.6% (2/7)83.3% (5/6)0% (0/1)100% (3/3)
      Funisitis0% (0/7)50% (3/6)0% (0/1)33.3% (1/3)
      Significant neonatal morbidity0% (0/9)33.3% (2/6)0% (0/1)33.3% (1/3)
      Data are median (interquartile ranges for group A and B, range for group D) or percentage (n/N).
      MMP-8, matrix metalloproteinase−8; PCR, polymerase chain reaction; WBC, white blood cell.
      Yoon et al. Antibiotics in preterm labor with intra-amniotic inflammation. Am J Obstet Gynecol 2019.
      a P < .05 compared to Group A
      b Some patients restarted antibiotic administration because they developed preterm rupture of membranes or preterm labor and intra-amniotic infection/inflammation after the discontinuation of antibiotics as intra-amniotic infection/inflammation resolved and preterm labor stopped. This duration was not included in this analysis
      c Patient case who underwent amniocentesis at or beyond 30 weeks was excluded from the analysis.

      Comment

      Principal findings of the study

      The principal findings of the study were as follows: 1) antibiotics were effective in treating intra-amniotic infection/inflammation in women with preterm labor and intact membranes, as demonstrated by analysis of amniotic fluid obtained before and after antibiotics were administered; 2) resolution of intra-amniotic infection/inflammation was objectively demonstrated in 79% of patients (15/19) who received the antimicrobial agents and had a follow-up amniocentesis; 3) the overall treatment success (defined as resolution of intra-amniotic inflammation or infection, or delivery ≥37 weeks) rate among patients who underwent follow-up amniocentesis was 84% (16/19). The overall success rate among all women with intra-amniotic infection/inflammation who received the antimicrobial agents was 32% (16/50).

      Prevalence and clinical importance of intra-amniotic infection/inflammation in patients with preterm labor and intact membranes

      The frequency of an amniotic fluid culture positive for microorganisms in patients presenting with an episode of preterm labor and intact membranes is approximately 10%,
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      • Smith C.V.
      Ureaplasma/Mycoplasma-infected amniotic fluid: pregnancy outcome in treated and nontreated patients.
      • Jacobsson B.
      • Mattsby-Baltzer I.
      • Andersch B.
      • et al.
      Microbial invasion and cytokine response in amniotic fluid in a Swedish population of women in preterm labor.
      When microorganisms invade the human fetus, a systemic inflammatory response can be elicited, and this condition is referred to as FIRS (diagnosed by an elevated umbilical cord blood plasma interleukin-6 concentration). This condition is associated with a higher rate of neonatal complications
      • Gomez R.
      • Romero R.
      • Ghezzi F.
      • Yoon B.H.
      • Mazor M.
      • Berry S.M.
      The fetal inflammatory response syndrome.
      • Romero R.
      • Gomez R.
      • Ghezzi F.
      • et al.
      A fetal systemic inflammatory response is followed by the spontaneous onset of preterm parturition.
      because, before birth, these fetuses have multi-systemic involvement or dysfunction.
      • Gotsch F.
      • Romero R.
      • Kusanovic J.P.
      • et al.
      The fetal inflammatory response syndrome.
      Examples include leukocyte activation,
      • Berry S.M.
      • Romero R.
      • Gomez R.
      • et al.
      Premature parturition is characterized by in utero activation of the fetal immune system.
      leukocytosis,
      • Chaiworapongsa T.
      • Romero R.
      • Berry S.M.
      • et al.
      The role of granulocyte colony-stimulating factor in the neutrophilia observed in the fetal inflammatory response syndrome.
      adrenal gland hyperactivity (elevated concentrations of cortisol in peripheral blood),
      • Yoon B.H.
      • Romero R.
      • Jun J.K.
      • et al.
      An increase in fetal plasma cortisol but not dehydroepiandrosterone sulfate is followed by the onset of preterm labor in patients with preterm premature rupture of the membranes.
      cardiac dysfunction,
      • Romero R.
      • Espinoza J.
      • Goncalves L.F.
      • et al.
      Fetal cardiac dysfunction in preterm premature rupture of membranes.
      • Mitchell T.
      • MacDonald J.W.
      • Srinouanpranchanh S.
      • et al.
      Evidence of cardiac involvement in the fetal inflammatory response syndrome: disruption of gene networks programming cardiac development in nonhuman primates.
      and increased concentrations of matrix-degrading enzymes in the amniotic fluid and fetal blood.
      • Athayde N.
      • Edwin S.S.
      • Romero R.
      • et al.
      A role for matrix metalloproteinase-9 in spontaneous rupture of the fetal membranes.
      • Locksmith G.J.
      • Clark P.
      • Duff P.
      • Schultz G.S.
      Amniotic fluid matrix metalloproteinase-9 levels in women with preterm labor and suspected intra-amniotic infection.
      • Maymon E.
      • Romero R.
      • Pacora P.
      • et al.
      Matrilysin (matrix metalloproteinase 7) in parturition, premature rupture of membranes, and intrauterine infection.
      • Locksmith G.J.
      • Clark P.
      • Duff P.
      • Saade G.R.
      • Schultz G.S.
      Amniotic fluid concentrations of matrix metalloproteinase 9 and tissue inhibitor of metalloproteinase 1 during pregnancy and labor.
      • Maymon E.
      • Romero R.
      • Pacora P.
      • et al.
      A role for the 72 kDa gelatinase (MMP-2) and its inhibitor (TIMP-2) in human parturition, premature rupture of membranes and intraamniotic infection.
      • Vadillo-Ortega F.
      • Sadowsky D.W.
      • Haluska G.J.
      • et al.
      Identification of matrix metalloproteinase-9 in amniotic fluid and amniochorion in spontaneous labor and after experimental intrauterine infection or interleukin-1 beta infusion in pregnant rhesus monkeys.
      FIRS is a risk factor for neonatal morbidity as well as long-term complications such as cerebral palsy
      • Yoon B.H.
      • Jun J.K.
      • Romero R.
      • et al.
      Amniotic fluid inflammatory cytokines (interleukin-6, interleukin-1beta, and tumor necrosis factor-alpha), neonatal brain white matter lesions, and cerebral palsy.
      • Yoon B.H.
      • Romero R.
      • Park J.S.
      • et al.
      Fetal exposure to an intra-amniotic inflammation and the development of cerebral palsy at the age of three years.
      and chronic lung disease.
      • Yoon B.H.
      • Romero R.
      • Jun J.K.
      • et al.
      Amniotic fluid cytokines (interleukin-6, tumor necrosis factor-alpha, interleukin-1 beta, and interleukin-8) and the risk for the development of bronchopulmonary dysplasia.
      • Lee J.
      • Oh K.J.
      • Yang H.J.
      • Park J.S.
      • Romero R.
      • Yoon B.H.
      The importance of intra-amniotic inflammation in the subsequent development of atypical chronic lung disease.
      • Lee J.
      • Oh K.J.
      • Park C.W.
      • Park J.S.
      • Jun J.K.
      • Yoon B.H.
      The presence of funisitis is associated with a decreased risk for the development of neonatal respiratory distress syndrome.
      • Yoon B.H.
      • Romero R.
      • Kim K.S.
      • et al.
      A systemic fetal inflammatory response and the development of bronchopulmonary dysplasia.
      In summary, a strong body of evidence indicates that fetal exposure to microorganisms or intra-amniotic inflammation is associated with adverse outcome.
      • Romero R.
      • Dey S.K.
      • Fisher S.J.
      Preterm labor: one syndrome, many causes.
      • Gravett M.G.
      • Witkin S.S.
      • Haluska G.J.
      • Edwards J.L.
      • Cook M.J.
      • Novy M.J.
      An experimental model for intraamniotic infection and preterm labor in rhesus monkeys.
      • Yoon B.H.
      • Chang J.W.
      • Romero R.
      Isolation of Ureaplasma urealyticum from the amniotic cavity and adverse outcome in preterm labor.
      • Yoon B.H.
      • Romero R.
      • Lim J.H.
      • et al.
      The clinical significance of detecting Ureaplasma urealyticum by the polymerase chain reaction in the amniotic fluid of patients with preterm labor.
      • Novy M.J.
      • Duffy L.
      • Axthelm M.K.
      • et al.
      Ureaplasma parvum or Mycoplasma hominis as sole pathogens cause chorioamnionitis, preterm delivery, and fetal pneumonia in rhesus macaques.
      • Oh K.J.
      • Hong J.S.
      • Romero R.
      • Yoon B.H.
      The frequency and clinical significance of intra-amniotic inflammation in twin pregnancies with preterm labor and intact membranes.
      • Yoon B.H.
      • Park C.W.
      • Chaiworapongsa T.
      Intrauterine infection and the development of cerebral palsy.
      • Oh K.J.
      • Park J.Y.
      • Lee J.
      • Hong J.S.
      • Romero R.
      • Yoon B.H.
      The combined exposure to intra-amniotic inflammation and neonatal respiratory distress syndrome increases the risk of intraventricular hemorrhage in preterm neonates.
      • Shim S.S.
      • Romero R.
      • Hong J.S.
      • et al.
      Clinical significance of intra-amniotic inflammation in patients with preterm premature rupture of membranes.
      • Maymon E.
      • Romero R.
      • Pacora P.
      • et al.
      Human neutrophil collagenase (matrix metalloproteinase 8) in parturition, premature rupture of the membranes, and intrauterine infection.
      • Yoon B.H.
      • Romero R.
      • Park J.S.
      • et al.
      Fetal exposure to an intra-amniotic inflammation and the development of cerebral palsy at the age of three years.
      • Romero R.
      • Yoon B.H.
      • Kenney J.S.
      • Gomez R.
      • Allison A.C.
      • Sehgal P.B.
      Amniotic fluid interleukin-6 determinations are of diagnostic and prognostic value in preterm labor.
      • Romero R.
      • Yoon B.H.
      • Mazor M.
      • et al.
      The diagnostic and prognostic value of amniotic fluid white blood cell count, glucose, interleukin-6, and gram stain in patients with preterm labor and intact membranes.
      • Yoon B.H.
      • Kim C.J.
      • Romero R.
      • et al.
      Experimentally induced intrauterine infection causes fetal brain white matter lesions in rabbits.
      • Romero R.
      • Espinoza J.
      • Goncalves L.F.
      • Kusanovic J.P.
      • Friel L.
      • Hassan S.
      The role of inflammation and infection in preterm birth.
      • Strunk T.
      • Inder T.
      • Wang X.
      • Burgner D.
      • Mallard C.
      • Levy O.
      Infection-induced inflammation and cerebral injury in preterm infants.
      Despite this overwhelming evidence, obstetricians in practice do not routinely ascertain whether patients with preterm labor have intra-amniotic infection/inflammation. The reason is 2-fold: first, the best method to determine the presence of intra-amniotic infection/inflammation is analysis of amniotic fluid, which requires an invasive procedure (amniocentesis); second, the evidence that treatment with antimicrobial agents can eradicate intra-amniotic infection has been based on case reports. Therefore, in practice, clinicians rely on signs and symptoms of clinical chorioamnionitis (eg, fever, maternal tachycardia, etc) to exclude intra-amniotic infection. However, it is now well established that these clinical signs are both insensitive and nonspecific for the identification of intra-amniotic infection in both preterm
      • Yoon B.H.
      • Chang J.W.
      • Romero R.
      Isolation of Ureaplasma urealyticum from the amniotic cavity and adverse outcome in preterm labor.
      • Yoon B.H.
      • Romero R.
      • Moon J.B.
      • et al.
      Clinical significance of intra-amniotic inflammation in patients with preterm labor and intact membranes.
      • Yoon B.H.
      • Yang S.H.
      • Jun J.K.
      • Park K.H.
      • Kim C.J.
      • Romero R.
      Maternal blood C-reactive protein, white blood cell count, and temperature in preterm labor: a comparison with amniotic fluid white blood cell count.
      • Oh K.J.
      • Kim S.M.
      • Hong J.S.
      • et al.
      Twenty-four percent of patients with clinical chorioamnionitis in preterm gestations have no evidence of either culture-proven intraamniotic infection or intraamniotic inflammation.
      • Revello R.
      • Alcaide M.J.
      • Abehsera D.
      • et al.
      Prediction of chorioamnionitis in cases of intraamniotic infection by ureaplasma urealyticum in women with very preterm premature rupture of membranes or preterm labour.
      and term
      • Romero R.
      • Chaemsaithong P.
      • Korzeniewski S.J.
      • et al.
      Clinical chorioamnionitis at term II: the intra-amniotic inflammatory response.
      • Romero R.
      • Chaemsaithong P.
      • Docheva N.
      • et al.
      Clinical chorioamnionitis at term VI: acute chorioamnionitis and funisitis according to the presence or absence of microorganisms and inflammation in the amniotic cavity.
      • Romero R.
      • Miranda J.
      • Kusanovic J.P.
      • et al.
      Clinical chorioamnionitis at term I: microbiology of the amniotic cavity using cultivation and molecular techniques.
      • Romero R.
      • Chaemsaithong P.
      • Docheva N.
      • et al.
      Clinical chorioamnionitis at term IV: the maternal plasma cytokine profile.
      • Romero R.
      • Chaemsaithong P.
      • Docheva N.
      • et al.
      Clinical chorioamnionitis at term V: umbilical cord plasma cytokine profile in the context of a systemic maternal inflammatory response.
      • Martinez-Varea A.
      • Romero R.
      • Xu Y.
      • et al.
      Clinical chorioamnionitis at term VII: the amniotic fluid cellular immune response.
      • Chaiyasit N.
      • Romero R.
      • Chaemsaithong P.
      • et al.
      Clinical chorioamnionitis at term VIII: a rapid MMP-8 test for the identification of intra-amniotic inflammation.
      gestations. This is also the case for maternal circulating white blood cell count and other biomarkers of the acute phase response (such as serum C-reactive protein).
      • Mazor M.
      • Kassis A.
      • Horowitz S.
      • et al.
      Relationship between C-reactive protein levels and intraamniotic infection in women with preterm labor.
      • Yoon B.H.
      • Yang S.H.
      • Jun J.K.
      • Park K.H.
      • Kim C.J.
      • Romero R.
      Maternal blood C-reactive protein, white blood cell count, and temperature in preterm labor: a comparison with amniotic fluid white blood cell count.
      • Romero R.
      • Yoon B.H.
      • Mazor M.
      • et al.
      The diagnostic and prognostic value of amniotic fluid white blood cell count, glucose, interleukin-6, and gram stain in patients with preterm labor and intact membranes.
      • Yoon B.H.
      • Jun J.K.
      • Park K.H.
      • Syn H.C.
      • Gomez R.
      • Romero R.
      Serum C-reactive protein, white blood cell count, and amniotic fluid white blood cell count in women with preterm premature rupture of membranes.
      • Lee S.Y.
      • Park K.H.
      • Jeong E.H.
      • Oh K.J.
      • Ryu A.
      • Park K.U.
      Relationship between maternal serum C-reactive protein, funisitis and early-onset neonatal sepsis.
      One argument against the analysis of amniotic fluid has been that results were not immediately available to affect patient management, as culture for microorganisms may take several days. However, rapid tests are now available for the diagnosis of intra-amniotic inflammation (such as amniotic fluid white blood cell count, glucose, amniotic fluid MMP-8, or interleukin-6, among others),
      • Gauthier D.W.
      • Meyer W.J.
      • Bieniarz A.
      Correlation of amniotic fluid glucose concentration and intraamniotic infection in patients with preterm labor or premature rupture of membranes.
      • Hussey M.J.
      • Levy E.S.
      • Pombar X.
      • Meyer P.
      • Strassner H.T.
      Evaluating rapid diagnostic tests of intra-amniotic infection: Gram stain, amniotic fluid glucose level, and amniotic fluid to serum glucose level ratio.
      • Chaemsaithong P.
      • Romero R.
      • Korzeniewski S.J.
      • et al.
      A rapid interleukin-6 bedside test for the identification of intra-amniotic inflammation in preterm labor with intact membranes.
      • Nien J.K.
      • Yoon B.H.
      • Espinoza J.
      • et al.
      A rapid MMP-8 bedside test for the detection of intra-amniotic inflammation identifies patients at risk for imminent preterm delivery.
      • Kim S.M.
      • Romero R.
      • Lee J.
      • et al.
      About one-half of early spontaneous preterm deliveries can be identified by a rapid matrix metalloproteinase-8 (MMP-8) bedside test at the time of mid-trimester genetic amniocentesis.
      • Kim K.W.
      • Romero R.
      • Park H.S.
      • et al.
      A rapid matrix metalloproteinase-8 bedside test for the detection of intraamniotic inflammation in women with preterm premature rupture of membranes.
      • Chaemsaithong P.
      • Romero R.
      • Docheva N.
      • et al.
      Comparison of rapid MMP-8 and interleukin-6 point-of-care tests to identify intra-amniotic inflammation/infection and impending preterm delivery in patients with preterm labor and intact membranes.
      • Romero R.
      • Yoon B.H.
      • Mazor M.
      • et al.
      The diagnostic and prognostic value of amniotic fluid white blood cell count, glucose, interleukin-6, and gram stain in patients with preterm labor and intact membranes.
      • Chaiyasit N.
      • Romero R.
      • Chaemsaithong P.
      • et al.
      Clinical chorioamnionitis at term VIII: a rapid MMP-8 test for the identification of intra-amniotic inflammation.
      • Yoon B.H.
      • Jun J.K.
      • Park K.H.
      • Syn H.C.
      • Gomez R.
      • Romero R.
      Serum C-reactive protein, white blood cell count, and amniotic fluid white blood cell count in women with preterm premature rupture of membranes.
      • Romero R.
      • Quintero R.
      • Nores J.
      • et al.
      Amniotic fluid white blood cell count: a rapid and simple test to diagnose microbial invasion of the amniotic cavity and predict preterm delivery.
      • Romero R.
      • Yoon B.H.
      • Mazor M.
      • et al.
      A comparative study of the diagnostic performance of amniotic fluid glucose, white blood cell count, interleukin-6, and gram stain in the detection of microbial invasion in patients with preterm premature rupture of membranes.
      • Dildy G.A.
      • Pearlman M.D.
      • Smith L.G.
      • Tortolero-Luna G.
      • Faro S.
      • Cotton D.B.
      Amniotic fluid glucose concentration: a marker for infection in preterm labor and preterm premature rupture of membranes.
      • Greig P.C.
      • Ernest J.M.
      • Teot L.
      Low amniotic fluid glucose levels are a specific but not a sensitive marker for subclinical intrauterine infections in patients in preterm labor with intact membranes.
      • Park C.W.
      • Lee S.M.
      • Park J.S.
      • Jun J.K.
      • Romero R.
      • Yoon B.H.
      The antenatal identification of funisitis with a rapid MMP-8 bedside test.
      • Chaemsaithong P.
      • Romero R.
      • Korzeniewski S.J.
      • et al.
      A point of care test for interleukin-6 in amniotic fluid in preterm prelabor rupture of membranes: a step toward the early treatment of acute intra-amniotic inflammation/infection.
      and for the diagnosis of infection using PCR.
      • Yoon B.H.
      • Romero R.
      • Lim J.H.
      • et al.
      The clinical significance of detecting Ureaplasma urealyticum by the polymerase chain reaction in the amniotic fluid of patients with preterm labor.
      • DiGiulio D.B.
      • Romero R.
      • Amogan H.P.
      • et al.
      Microbial prevalence, diversity and abundance in amniotic fluid during preterm labor: a molecular and culture-based investigation.
      • Oh K.J.
      • Lee S.E.
      • Jung H.
      • Kim G.
      • Romero R.
      • Yoon B.H.
      Detection of ureaplasmas by the polymerase chain reaction in the amniotic fluid of patients with cervical insufficiency.
      • Romero R.
      • Miranda J.
      • Chaiworapongsa T.
      • et al.
      A novel molecular microbiologic technique for the rapid diagnosis of microbial invasion of the amniotic cavity and intra-amniotic infection in preterm labor with intact membranes.
      • Yoon B.H.
      • Romero R.
      • Kim M.
      • et al.
      Clinical implications of detection of Ureaplasma urealyticum in the amniotic cavity with the polymerase chain reaction.
      • DiGiulio D.B.
      • Romero R.
      • Kusanovic J.P.
      • et al.
      Prevalence and diversity of microbes in the amniotic fluid, the fetal inflammatory response, and pregnancy outcome in women with preterm pre-labor rupture of membranes.
      • Rowlands S.
      • Danielewski J.A.
      • Tabrizi S.N.
      • Walker S.P.
      • Garland S.M.
      Microbial invasion of the amniotic cavity in midtrimester pregnancies using molecular microbiology.
      • Rehbinder E.M.
      • Lodrup Carlsen K.C.
      • Staff A.C.
      • et al.
      Is amniotic fluid of women with uncomplicated term pregnancies free of bacteria?.

      Antibiotic administration to patients in preterm labor with intact membranes

      The evidence that intra-amniotic infection is causally linked to spontaneous preterm labor and delivery coalesced in the 1980s;
      • Romero R.
      • Quintero R.
      • Oyarzun E.
      • et al.
      Intraamniotic infection and the onset of labor in preterm premature rupture of the membranes.
      • Skoll M.A.
      • Moretti M.L.
      • Sibai B.M.
      The incidence of positive amniotic fluid cultures in patients preterm labor with intact membranes.