Pathophysiology, diagnosis, and management of intraamniotic infection

Association between intrapartum antibiotic prophylaxis for Group B Streptococcus colonization and clinical chorioamnionitis among patients undergoing induction of labor at term

BACKGROUND

Rectovaginal colonization with Group B Streptococcus during pregnancy has historically been shown to be associated with an increased risk of clinical chorioamnionitis and peripartum infectious morbidity.

OBJECTIVE

Newer observational data in the era of intrapartum antibiotic prophylaxis suggest a possible reversal of this association; however, it is unclear if this is related to differences in labor management for those with and without Group B Streptococcus colonization. We therefore sought to assess the association between intrapartum antibiotic prophylaxis for Group B Streptococcus colonization and clinical chorioamnionitis within the context of a randomized induction of labor trial with a standardized labor protocol.

STUDY DESIGN

We performed an exploratory secondary analysis of a randomized trial of patients undergoing term induction at a tertiary care center. Patients received third trimester Group B Streptococcus screening and intrapartum antibiotic prophylaxis as routine care. Group B Streptococcus detection was performed using a carrot broth-enhanced subculture to Group B Streptococcus Detect approach (Hardy Diagnostics, Santa Maria, CA). Labor management was protocolized per the trial. Patients with unknown Group B Streptococcus status or who did not receive intrapartum antibiotic prophylaxis, if indicated, were excluded. The primary outcome was diagnosis of clinical chorioamnionitis, compared between patients who received intrapartum antibiotic prophylaxis for known Group B Streptococcus positive status (by culture, history, or Group B Streptococcus bacteriuria) and those who were Group B Streptococcus negative and did not receive intrapartum antibiotic prophylaxis. Secondary outcomes included postpartum endometritis, wound infection, a composite maternal peripartum infectious morbidity, and neonatal outcomes.

RESULTS

A total of 491 patients were enrolled in the trial. Of these, 466 had a known Group B Streptococcus status and received or did not receive intrapartum antibiotic prophylaxis accordingly and were included in this analysis: 292 (62.7%) were Group B Streptococcus negative and did not receive intrapartum antibiotic prophylaxis, and 174 (37.3%) were Group B Streptococcus positive and received intrapartum antibiotic prophylaxis. The majority of patients were Non-Hispanic Black (78.1%) and nulliparous (59.7%). There were no differences in demographic, clinical, induction or labor characteristics between groups. Patients who were Group B Streptococcus positive had a 49% lower rate of clinical chorioamnionitis (8.1% vs 14.7%, odds ratio, 0.51; P=.03) and a lower rate of peripartum infectious morbidity (8.1% vs 15.8%, odds ratio, 0.47; P=.02) compared to those who were Group B Streptococcus negative. Infants born to patients who were Group B Streptococcus positive were significantly less likely to be admitted to the neonatal intensive care unit (3.4% vs 15.1%, P<.001).

CONCLUSION

Although Group B Streptococcus colonization has historically been considered a risk factor for clinical chorioamnionitis, in the era of universal antibiotic prophylaxis for Group B Streptococcus positive patients, our findings support the point that intrapartum antibiotic prophylaxis for Group B Streptococcus positivity is associated with lower rates of clinical chorioamnionitis and peripartum infectious morbidity among patients undergoing induction with protocolized labor management. These findings demonstrate that intrapartum antibiotic prophylaxis for Group B Streptococcus may protect against perinatal infectious morbidity, a phenomenon that warrants further investigation.

Expressed Breast Milk Analysis: Role of Individualized Protein Fortification to Avoid Protein Deficit After Preterm Birth and Improve Infant Outcomes

Background: Expressed breast milk (EBM) protein content is highly variable between mothers and often below published values that are still used for EBM protein fortification strategies. This approach may result in significant protein deficit and suboptimal protein energy (P/E) ratio. The study aim was to determine whether individualized EBM protein analysis and fortification will reduce preterm infant protein deficits and improve growth and neurodevelopmental outcome. Study Methods: In a single-center randomized, blinded study of infants born at 24 0/7-29 6/7 weeks, mother-specific protein values measured by a milk analyzer were used to individualize infant-specific protein intake (interventional group, IG), and compared this to a standardized protein fortification scheme based on published values of EBM protein content of 1.4 g/dL (control group, CG). For IG, milk analyzer protein values of mother's EBM were used to adjust protein content of the EBM. The CG EBM protein content was adjusted using the standard published value of 1.4 g/dL and not based on milk analyzer values. EBM protein content, protein intake, protein/energy (P/E) ratio, weight (WT), head circumference (HC), length (L), growth velocity (GV) from 2 to 6 weeks of age, WT, HC and L Z-Scores at 32- and 35-weeks PMA, and lean body mass (35 weeks PMA skin fold thickness) were measured. Neurodevelopment was assessed by Bayley III at average 24 months corrected gestational age (CGA). Results: EBM protein content before fortification was significantly below published values of 1.4 g/dL at all time points in both CG and IG. CG protein deficit was significantly decreased and progressively worsened throughout the study. Individualized protein fortification in IG avoided protein deficit and optimized P/E ratio. Although no significant change in short-term GV (at 6 weeks of age) was seen between groups, IG infants born at <27 weeks had significant improvements in WT and L z-scores, and leaner body mass at 32 and 35 weeks PMA. IG exhibited significantly improved cognitive scores at 24 months CGA. Conclusions: Infant-specific protein supplementation of mother's EBM optimized P/E ratio by eliminating protein deficit and improved growth z scores at 32- and 35-weeks PMA and neurocognitive testing at 24 months.

[Current approach in preterm prelabor rupture of membranes: new definitions? Is CRP determination useful? Are alternatives in sight?]

Around 3% of all pregnancies are complicated by preterm prelabor rupture of membranes (PPROM) before 37 + 0 weeks of gestation. Since PPROM is likely to be associated with microbial invasion of the amniotic cavity (MIAC)-either before or secondary to PPROM-the risk of developing intraamniotic inflammation (IAI) is high. IAI is associated with short latency to delivery and with adverse short- and long-term outcomes for the newborn, especially in cases of fetal inflammatory response syndrome (FIRS). Prediction of IAI based on maternal parameters is difficult or impossible. The recently established definition of triple I ("infection, inflammation, or both") is based on the parameter "maternal body temperature". If this is increased to ≥ 38.0 °C and there is no other reason to explain maternal fever, the finding is suspicious for triple I if at least one other of the following parameters can be found: fetal tachycardia > 160 bpm for at least 10 min, maternal leukocytes > 15,000/µl without administration of corticosteroids, or purulent fluid from the cervical os. Pregnancies suspicious for triple I should be terminated. The confirmation of triple I is only possible by placental histology (histologically confirmed chorioamnionitis, HCA). Confirmation based on amniocentesis (positive Gram stain, low glucose concentration [<14 mg/dl], elevated white blood cell count [>30 cells/mm³], positive culture) takes too long and is unreliable. Serial determinations of C‑reactive protein also do not allow reliable diagnosis of IAI. Studies using interleukin 6 measurements from the posterior fornix and/or cervical os are promising methods, the validation of which is awaited.

Comparison between leukocyte esterase activity and histopathological examination in identifying chorioamnionitis

Objective

To compare the sensitivity and specificity of leukocyte esterase activity (LEA) to histopathological examination in diagnosing chorioamnionitis.

Methods

We compared the diagnostic tests performed at Dr. Mohammad Hoesin Hospital, Palembang, Indonesia, from September 2015 to April 2016. Ninety-one pregnant women were included in the study. The LEA and histopathological examination were carried out with neonatal sepsis the main outcome. Data were analyzed using the SPSS version 21.0 and MedCalc statistics.

Results

Chorioamnionitis was detected in 54 (77.1%) patients with a gestational age ≥37 weeks and in 16 (22.9%) patients with a gestational age <37 weeks. The duration of membrane rupture was significantly associated with chorioamnionitis (P = 0.001 and P = 0.011). Neonatal sepsis was also significantly associated with chorioamnionitis in both groups (P = 0.014 and P = 0.036). A LEA value with the cut-off point >0.5 was able to significantly predict chorioamnionitis with 98.6% sensitivity and 95.2% specificity, providing better accuracy in diagnosing chorioamnionitis in the preterm pregnancy group.

Conclusion

LEA had a very good predictive value for chorioamnionitis with better accuracy in diagnosing chorioamnionitis in preterm pregnancy.

Clinical chorioamnionitis at term VIII: a rapid MMP-8 test for the identification of intra-amniotic inflammation

OBJECTIVE

Clinical chorioamnionitis is the most common infection/inflammatory process diagnosed in labor and delivery units worldwide. The condition is a syndrome that can be caused by (1) intra-amniotic infection, (2) intra-amniotic inflammation without demonstrable microorganisms (i.e. sterile intra-amniotic inflammation), and (3) maternal systemic inflammation that is not associated with intra-amniotic inflammation. The presence of intra-amniotic inflammation is a risk factor for adverse maternal and neonatal outcomes in a broad range of obstetrical syndromes that includes clinical chorioamnionitis at term. Although the diagnosis of intra-amniotic infection has relied on culture results, such information is not immediately available for patient management. Therefore, the diagnosis of intra-amniotic inflammation could be helpful as a proxy for intra-amniotic infection, while results of microbiologic studies are pending. A rapid test is now available for the diagnosis of intra-amniotic inflammation, based on the determination of neutrophil collagenase or matrix metalloproteinase-8 (MMP-8). The objectives of this study were (1) to evaluate the diagnostic indices of a rapid MMP-8 test for the identification of intra-amniotic inflammation/infection in patients with the diagnosis of clinical chorioamnionitis at term, and (2) to compare the diagnostic performance of a rapid MMP-8 test to that of a conventional enzyme-linked immunosorbent assay (ELISA) interleukin (IL)-6 test for patients with clinical chorioamnionitis at term.

MATERIALS AND METHODS

A retrospective cohort study was conducted. A transabdominal amniocentesis was performed in patients with clinical chorioamnionitis at term (n=44). Amniotic fluid was analyzed using cultivation techniques (for aerobic and anaerobic bacteria as well as genital Mycoplasmas) and broad-range polymerase chain reaction (PCR) coupled with electrospray ionization mass spectrometry (PCR/ESI-MS). Amniotic fluid IL-6 concentrations were determined by ELISA, and rapid MMP-8 results were determined by Yoon's MMP-8 Check®. Intra-amniotic inflammation was defined as an elevated amniotic fluid IL-6 concentration ≥2.6 ng/mL, and intra-amniotic infection was diagnosed by the presence of microorganisms in the amniotic fluid accompanied by intra-amniotic inflammation. The diagnostic indices of Yoon's MMP-8 Check® for the identification of intra-amniotic inflammation were calculated. In order to objectively compare Yoon's MMP-8 Check® with the ELISA IL-6 test for the identification of intra-amniotic inflammation, we used an amniotic fluid white blood cell (WBC) count ≥50 cells/mm3 to define intra-amniotic inflammation.

RESULTS

(1) A positive rapid MMP-8 test had a sensitivity of 82.4% (28/34), specificity of 90% (9/10), positive predictive value of 96.6% (28/29), negative predictive value of 60% (9/15), positive likelihood ratio 8.2 (95% CI 1.3-53.2), and negative likelihood ratio 0.2 (95% CI 0.1-0.4) for the identification of intra-amniotic inflammation (prevalence 77.3%); (2) a positive rapid MMP-8 test had a sensitivity of 91.7% (22/24), specificity of 65% (13/20), positive predictive value of 75.9% (22/29), negative predictive value of 86.7% (13/15), positive likelihood ratio of 2.6 (95% CI 1.4-4.8), and negative likelihood ratio of 0.1 (95% CI 0.03-0.5) for the identification of intra-amniotic infection; (3) the rapid MMP-8 test had a significantly higher specificity than the ELISA IL-6 test in the identification of intra-amniotic inflammation as determined by an amniotic fluid WBC count ≥50 cells/mm3. The sensitivity and accuracy of the rapid MMP-8 test were comparable to those of the ELISA IL-6 test; and (4) importantly, the rapid MMP-8 test had 100% sensitivity and 100% negative predictive value in the identification of neonates affected with fetal inflammatory response syndrome (FIRS).

CONCLUSION

The rapid diagnosis of intra-amniotic inflammation is possible by analysis of amniotic fluid using a point-of-care test for MMP-8. Patients with a positive test are at risk of delivering a neonate affected with systemic inflammation, a risk factor for adverse neonatal outcome.

Aerococcus christensenii as Part of Severe Polymicrobial Chorioamnionitis in a Pregnant Woman

Chorioamnionitis is a potentially life threatening infection of the fetal membranes, commonly caused by ascending bacteria from the vagina and cervix. In our case, a healthy nullipara with a term pregnancy presented clinical signs of infection after induced labour with an intracervical balloon. Thick green and foul smelling amniotic fluid was observed and culture showed massive growth of Aerococcus christensenii, a facultative anaerob species found in the human vagina, previously only rarely alleged to cause invasive infection. Additional testing with 16S rRNA gene analysis also identified the presence of Gemella asaccharolytica, Snethia sanguinegens, Parvimonas micra and Streptobacillus moniliformis. The patient was treated with cefuroxime and metronidazole and recovered quickly. The newborn showed no signs of infection. This case points at the possible role of these pathogens in female genital tract infections. The case also underlines the importance of the combination of culture and culture independent diagnostic approaches to reveal possible polymicrobial natures of selected infections, in this case chorioamnionitis.

The Role of Megalin in the Transport of Gentamicin Across BeWo Cells, an In Vitro Model of the Human Placenta

Aminoglycosides (AG) are known to readily cross the placenta, although the mechanisms responsible for placental transport have not been characterized. Megalin is expressed in human placenta, and it is reasonable to speculate, given its role in renal AG uptake, that it is similarly involved in placental transport. However, the role of megalin in placental AG uptake has not been established. An in vitro model to study megalin-mediated placental transport has also not been previously described. The objectives of this study, therefore, were to evaluate the human choriocarcinoma (BeWo) cell line as a model to study megalin-mediated placental transport and to assess the uptake kinetics of gentamicin, an AG antibiotic, using this in vitro model. BeWo cells were grown on Transwell® plates, and megalin expression and functional activity were assessed. Uptake of (3)H-gentamicin was also evaluated in the presence and absence of megalin inhibitors. Expression of megalin protein and mRNA in BeWo cells were confirmed via immunoblot and qPCR analysis. Uptake of fluorescein isothiocyanate (FITC)-labeled bovine serum albumin (BSA) (a megalin substrate) was time-, concentration-, and temperature-dependent consistent with a transporter-mediated process. FITC-BSA uptake was also significantly reduced in the presence of unlabeled gentamicin (a megalin substrate) and sodium maleate (to induce megalin shedding) suggesting that megalin is functionally active in BeWo cells. Gentamicin uptake exhibited time and temperature dependence, saturability and Michaelis-Menten kinetics, all of which suggest a transporter-mediated process. Gentamicin uptake was also significantly reduced in the presence of the megalin inhibitors RAP and EDTA suggesting that megalin is likely involved in gentamicin uptake.

Impact of fetal presentation on pregnancy outcome in preterm premature rupture of membranes

AIM OF THE STUDY

To determine the impact of fetal presentation on pregnancy outcome in preterm premature rupture of membranes (PPROM).

STUDY DESIGN

Retrospective.

MATERIALS AND METHODS

Fifty eight PPROM patients (gestational age of 24-34 wk, complicated by PPROM and latency more than 24 h) between January 2008 to December 2012 were categorized into cephalic and non cephalic and pregnancy outcome were analyzed with standard statistical methods including the Chi-square test, t- test and Mann Whitney test.

RESULTS

The non cephalic (20.7%, 12/58) and cephalic group (79.3%, 46/58) among the 58 patients with PPROM were demographically homogenous. PPROM was significantly earlier in non cephalic group although latency was not much different in both groups. Maternal complications (abruption, chorioamnionitis and post operative wound infection) as a composite were more in non cephalic group. Neonatal death was also significantly more in non cephalic than cephalic.

CONCLUSION

Non cephalic presentation at diagnosis of PPROM is likely to have an unfavorable effect on the maternal and fetal outcome.

A first look at chorioamnionitis management practice variation among US obstetricians

Objective. To examine practice patterns for diagnosis and treatment of chorioamnionitis among US obstetricians. Study Design. We distributed a mail-based survey to members of the American College of Obstetricians and Gynecologists, querying demographics, practice setting, and chorioamnionitis management strategies. We performed univariable and multivariable analyses. Results. Of 500 surveys distributed, 53.8% were returned, and 212 met study criteria and were analyzed. Most respondents work in group practice (66.0%), perform >100 deliveries per year (60.0%), have been in practice >10 years (77.3%), and work in a nonuniversity setting (85.1%). Temperature plus one additional criterion (61.3%) was the most common diagnostic strategy. Over 25 different primary antibiotic regimens were reported, including use of a single agent by 30.0% of respondents. A wide range of postpartum antibiotic duration was reported from no postpartum treatment (34.5% after vaginal delivery, 11.3% after cesarean delivery) to 48 hours of postpartum treatment (24.7% after vaginal delivery, 32.1% after cesarean delivery). No practitioner characteristic was independently associated with diagnostic or therapeutic strategies in multivariable analysis. Conclusion. There is a wide variation in contemporary clinical practices for the management of chorioamnionitis. This may represent a dearth of level I evidence. Future prospective clinical trials may provide more evidence-based practice recommendations for diagnosis and treatment of chorioamnionitis.

The frequency and clinical significance of intra-amniotic inflammation in women with preterm uterine contractility but without cervical change: do the diagnostic criteria for preterm labor need to be changed?

OBJECTIVE

The objective of this study was to determine the frequency and clinical significance of intra-amniotic inflammation in patients with preterm increased uterine contractility with intact membranes but without cervical change.

METHODS

Amniocentesis was performed in 132 patients with regular uterine contractions and intact membranes without cervical change. Amniotic fluid was cultured for bacteria and mycoplasmas and assayed for matrix metalloproteinase-8 (MMP-8). Intra-amniotic inflammation was defined as an elevated amniotic fluid MMP-8 concentration (>23 ng/mL).

RESULTS

(1) Intra-amniotic inflammation was present in 12.1% (16/132); (2) Culture-proven intra-amniotic infection was diagnosed in 3% (4/132) of patients without demonstrable cervical change on admission or during the period of observation; and (3) Patients with intra-amniotic inflammation had significantly higher rates of preterm delivery and adverse outcomes, and shorter amniocentesis-to-delivery intervals than those without intra-amniotic inflammation (P < 0.05 for each). Adverse outcomes included chorioamnionitis, funisitis, and neonatal death.

CONCLUSION

Intra-amniotic inflammation was present in 12% of patients with regular uterine contractions without cervical change, while culture-proven intra-amniotic infection was present in 3%. The presence of intra-amniotic inflammation was a significant risk factor for adverse neonatal outcomes. These observations question whether cervical changes should be required for the diagnosis of preterm labor, because patients without modifications in cervical status on admission or during a period of observation are at risk for adverse pregnancy outcomes.

Diagnosis and management of clinical chorioamnionitis

Chorioamnionitis is a common complication of pregnancy associated with significant maternal, perinatal, and long-term adverse outcomes. Adverse maternal outcomes include postpartum infections and sepsis whereas adverse infant outcomes include stillbirth, premature birth, neonatal sepsis, chronic lung disease, and brain injury leading to cerebral palsy and other neurodevelopmental disabilities. Research in the past 2 decades has expanded understanding of the mechanistic links between intra-amniotic infection and preterm delivery as well as morbidities of preterm and term infants. Recent and ongoing clinical research into better methods for diagnosing, treating, and preventing chorioamnionitis is likely to have a substantial impact on short and long-term outcomes in the neonate.

Once a pregnancy, always a cesarean? Rationale and feasibility of a randomized controlled trial

Although vaginal delivery has long been assumed to be the preferred route of delivery in women who have not had a prior cesarean delivery, some have recently advocated that women be offered the option of elective, primary cesarean delivery in all pregnancies. Available outcome data, however, do not permit ready comparison of these alternate plans for delivery. Important maternal outcomes include short-term complications such as death, bleeding, infection, and damage to pelvic organs as well as long-term effects on future pregnancies, fecal and urinary incontinence, and pelvic organ prolapse. Important neonatal outcomes include asphyxic and traumatic birth injury, infection, respiratory complications, and stillbirth. To weigh the relative merits of elective primary cesarean delivery and a trial of labor, a randomized controlled trial is needed. Such a trial would be both ethical and feasible.