Polymerase chain reaction in the detection of microbes in amniotic fluid

Prolonged use of antibiotics after birth is associated with increased morbidity in preterm infants with negative cultures

Background: Most preterm infants are exposed to a variable duration of antibiotic therapy after birth despite negative cultures. Data is emerging about the risks of prolonged antibiotics. We sought to assess the association between length of initial antibiotic course and neonatal outcomes in a cohort from a single large perinatal center.Methods: Retrospective cohort study of prospectively collected data on all infants with a birth weight of less than 1250 g hospitalized in our NICU in a 4 year window and who had negative blood and CSF cultures in the first 2 days of life. The primary outcome is a composite of necrotizing enterocolitis (NEC), late onset sepsis (LOS) and death evaluated using multivariable regression analysis.Results: A total of 620 infants less than 1250 g with negative cultures were eligible for study over a 4 year period. The 238 infants with more than 5 days initial antibiotic use were significantly smaller and of lower gestational age than the 382 infants who received up to 5 days of antibiotics. Their mothers had more clinical chorioamnionitis, less maternal hypertension and greater perinatal use of antibiotics. On multivariate analysis, infants who received empiric antibiotics for longer than 5 days had higher rates of neonatal morbidities after adjusting for gestational age, SNAP II, small-for-gestational age status, gender, maternal hypertension, prenatal steroid treatment, clinical chorioamnionitis, intrapartum antibiotic treatment, and multiple births. Composite outcome OR: 1.83 (1.15 to 2.92), LOS OR: 2.02 (1.20 to 3.39), bronchopulmonary dysplasia OR: 1.58 (1.04 to 2.29). Mortality and NEC were not significantly different.Conclusion: More than 5 days of antibiotic treatment in very preterm infants with negative cultures was associated with increased morbidity in our population, and that included BPD. It is of note that patterns of increased morbidity and/or mortality differ between studies. Prospective trials of clinical protocols for starting and stopping antibiotics in the very preterm infants are required.

Human Papillomavirus Infection as a Possible Cause of Spontaneous Abortion and Spontaneous Preterm Delivery

Based on the current literature, we aimed to provide an overview on Human Papillomavirus prevalence in normal pregnancies and pregnancies with adverse outcome. We conducted a systematic literature search in PubMed and Embase. Data extracted from the articles and used for analysis included HPV prevalence, pregnancy outcome, geographical location, investigated tissue types, and HPV detection methods. The overall HPV prevalence in normal full-term pregnancies was found to be 17.5% (95% CI; 17.3-17.7) for cervix, 8.3% (95% CI; 7.6-9.1) for placental tissue, 5.7% (95% CI; 5.1-6.3) for amniotic fluid, and 10.9% (95% CI; 10.1-11.7) for umbilical cord blood. Summary estimates for HPV prevalence of spontaneous abortions and spontaneous preterm deliveries, in cervix (spontaneous abortions: 24.5%, and preterm deliveries: 47%, resp.) and placenta (spontaneous abortions: 24.9%, and preterm deliveries: 50%, resp.), were identified to be higher compared to normal full-term pregnancies (P < 0.05 and P < 0.0001). Great variation in HPV prevalence was observed between study populations of different geographical locations. This review demonstrates an association between spontaneous abortion, spontaneous preterm delivery, and the presence of HPV in both the cervix and the placenta. However, a reliable conclusion is difficult to draw due to the limited number of studies conducted on material from pregnancies with adverse outcome and the risk of residual confounding.

Viral invasion of the amniotic cavity (VIAC) in the midtrimester of pregnancy

INTRODUCTION

The prevalence of viral infections in the amniotic fluid (AF) has not yet been ascertained. The aim of this study was to determine the prevalence of specific viral nucleic acids in the AF and its relationship to pregnancy outcome.

STUDY DESIGN

From a cohort of 847 consecutive women undergoing midtrimester amniocentesis, 729 cases were included in this study after exclusion of documented fetal anomalies, chromosomal abnormalities, unavailability of AF specimens and clinical outcomes. AF specimens were tested by quantitative real-time PCR for the presence of genome sequences of the following viruses: adenoviruses, herpes simplex virus (HSV), varicella zoster virus (VZV), human herpesvirus 6 (HHV6), human cytomegalovirus (HCMV), Epstein-Barr virus (EBV), parvovirus B19 and enteroviruses. Viral nucleic acid testing was also performed in maternal blood and cord blood in the population of women in whom AF was positive for viruses and in a control group of 29 women with AF negative for viral nucleic acids. The relationship between the presence of viruses and pregnancy and neonatal outcome was examined. The correlation between the presence of nucleic acids of viruses in the AF and the concentration of the cytokine interleukin-6 (IL-6) and the T cell chemokine CXCL-10 (or IP-10) in AF and maternal blood were analyzed.

RESULTS

Viral genome sequences were found in 16 of 729 (2.2%) AF samples. HHV6 was the most commonly detected virus (7 cases, 1.0%), followed by HCMV (6 cases, 0.8%), parvovirus B19 (2 cases, 0.3%) and EBV (1 case, 0.1%), while HSV, VZV, enteroviruses and adenoviruses were not found in this cohort. Corresponding viral DNA was also detected in maternal blood of six out of seven women with HHV6-positive AF and in the umbilical cord plasma, which was available in one case. In contrast, viral DNA was not detected in maternal blood of women with AF positive for parvovirus B19, HCMV, EBV or of women with AF negative for viruses. HHV6 genome copy number in AF and maternal blood was consistent with genomic integration of viral DNA and genetic infection in all women. There was no significant difference in the AF concentration of IL-6 and IP-10 between patients with and without VIAC. However, for HCMV, there was a significant relationship between viral copy number and IP-10 concentration in maternal blood and AF. The group of women with AF positive for viral DNA delivered at term healthy neonates without complications in 14 out of 16 cases. In one case of HHV6 infection in the AF, the patient developed gestational hypertension at term, and in another case of HHV6 infection in the AF, the patient delivered at 33 weeks after preterm premature rupture of membranes (PPROM).

CONCLUSION

Viral nucleic acids are detectable in 2.2% of AF samples obtained from asymptomatic women in the midtrimester. HHV6 was the most frequently detected virus in AF. Adenoviruses were not detected. Vertical transmission of HHV6 was demonstrated in one case.

Midtrimester amniotic fluid concentrations of interleukin-6 and interferon-gamma-inducible protein-10: evidence for heterogeneity of intra-amniotic inflammation and associations with spontaneous early (<32 weeks) and late (>32 weeks) preterm delivery

INTRODUCTION

Intra-amniotic inflammation is traditionally defined as an elevation of amniotic fluid interleukin (IL)-6. Previous case control studies have suggested an association between an elevated midtrimester amniotic fluid IL-6 and preterm delivery, although such an association has been recently challenged. Intra-amniotic inflammation can also be defined by an elevation of the T-cell chemokine, Interferon-gamma-inducible protein (IP)-10. An elevation in amniotic fluid IP-10 has been associated with chronic chorioamnionitis, a lesion frequently found in late spontaneous preterm birth and fetal death. In contrast, an elevation in amniotic fluid IL-6 is typically associated with acute chorioamnionitis and funisitis. This study was conducted to examine the relationship between an elevation in amniotic fluid IL-6 in the midtrimester and preterm delivery at or before 32 weeks of gestation, and the amniotic fluid concentration of IP-10 and preterm delivery after 32 weeks of gestation.

MATERIALS AND METHODS

This cohort study included 847 consecutive women undergoing genetic midtrimester amniocentesis; in 796 cases, amniotic fluid and pregnancy outcome was available for study after exclusion of abnormal karyotype and/or fetal congenital anomalies. Spontaneous preterm delivery was defined as early (≤32 weeks) or late (after 32 completed weeks of pregnancy). The amniotic fluid and maternal blood concentrations of IL-6 and IP-10 were measured by specific immunoassays.

RESULTS

1) The prevalence of preterm delivery was 8.3% (66/796), while those of early and late spontaneous preterm delivery were 1.5% (n=12), and 4.5% (n=36), respectively; 2) patients who had a spontaneous preterm delivery after 32 weeks of gestation had a higher median amniotic fluid IP-10 concentration than those who delivered at term [median 713 pg/mL, inter-quartile range (IQR) 509-1427 pg/mL vs. median 589 pg/mL, IQR 402-953 pg/mL; P=0.006] and an elevation of amniotic fluid IP-10 concentration above 502 pg/mL (derived from an ROC curve) was associated with late spontaneous preterm delivery [odds ratio 3.9 (95% CI 1.6-9.9)]; 3) patients who had a spontaneous preterm delivery ≤32 weeks of gestation had a higher median amniotic fluid IL-6 concentration than those who delivered at term [median 2052 pg/mL, IQR 435-3015 pg/mL vs. median 414 pg/mL, IQR 209-930 pg/mL; P=0.006], and an elevated amniotic fluid IL-6 concentration above 1740 pg/mL (derived from an ROC curve) was associated with early spontaneous preterm delivery [odds ratio 9.5 (95% CI 2.9-31.1)]; 4) subclinical intra-amniotic inflammation, defined as an elevation of IL-6 (≥2.9 ng/mL) or IP-10 (≥2.2 ng/mL) concentration above the 95th percentile of patients who had uncomplicated term delivery (n=652 for IL-6 and n=633 for IP-10), was observed in 6.3% (50/796) and 5.8% (45/770) of cases, respectively. Although each type of inflammation is a risk factor for spontaneous preterm delivery, many patients had a term delivery without complication; 5) the amniotic fluid in the midtrimester did not contain microorganisms detectable with cultivation techniques.

CONCLUSIONS

INTRA-amniotic inflammation is heterogeneous. Some patients have elevated amniotic fluid concentrations of IL-6, and are at risk for spontaneous preterm delivery before 32 weeks of gestation, while others have an elevated IP-10 (a chemotactic T-cell chemokine) and such patients are at risk for spontaneous preterm delivery after 32 weeks of gestation. A fraction of patients have subclinical intra-amniotic inflammation and deliver at term. The clinical significance of this condition remains to be determined.

Fetal serum β2-microglobulin as a marker for fetal infectious diseases

OBJECTIVES

To evaluate whether fetal serum beta2-microglobulin could be used as a marker of fetal cytomegalovirus (CMV) or toxoplasmosis infection.

METHODS

beta2-microglobulin was retrospectively assayed in fetal serum collected from 64 patients with maternal infectious seroconversion (toxoplasmosis in 49 cases, CMV in 15). Using a beta2-microglobulin cutoff of 5 mg/L, infection and control groups were compared.

RESULTS

Fetal serum beta2-microglobulin was >5 mg/L (5.2-13.5 mg/L) in 12 of the 13 cases with proved fetal toxoplasmosis infection, indicating 90% sensitivity. In the 39 pregnancies with maternal seroconversion but no laboratory signs of fetal infection, fetal serum beta2-microglobulin was <5 mg/L, indicating 100% specificity. Fetal serum was >5 mg/L (6.3-32 mg/L) in 14 of the 15 cases with proved fetal CMV infection, indicating 93.3% sensitivity. Specificity cannot be evaluated because maternal serum is not routinely screened for CMV during pregnancy.

CONCLUSIONS

Fetal serum beta2-microglobulin is a reliable marker of fetal CMV or toxoplasmosis infection, which can be used in ambiguous situations. Because this increase is not specific, fetal serum beta2-microglobulin would potentially be raised in other fetal infections.

Micronutrients and intrauterine infection, preterm birth and the fetal inflammatory response syndrome

Prematurity is the leading cause of perinatal morbidity and mortality worldwide. Intrauterine infection has emerged as a major cause of premature labor and delivery. It has been estimated that 25% of all preterm deliveries occur to mothers who have microbial invasion of the amniotic cavity, although these infections are mostly subclinical in nature. This article describes the pathways leading to intrauterine infection, microbiology, frequency and clinical consequences of infection. The pathophysiology of the fetal inflammatory response syndrome is reviewed, as is its relationship to long-term handicap, such as cerebral palsy and bronchopulmonary dysplasia. A possible role for two micronutrients, vitamins C and E, in the prevention of the preterm prelabor rupture of membranes and the consequences of fetal inflammation is considered. Research needs are listed.

Maternal serum and amniotic fluid cytokines in patients with preterm premature rupture of membranes with and without intrauterine infection

OBJECTIVES

To evaluate the role of interleukins (IL-1, IL-6), tumor necrosis factor alpha (TNFalpha) and for the first time interferon gamma (IFNgamma) and epidermal growth factor (EGF) in the pathogenesis of premature rupture of membranes (PROM) with and without confirmed intrauterine infection.

METHODS

Amniotic fluid was retrieved by transabdominal amniocentesis from 30 patients with PROM and 20 normal pregnant women with intact membranes of matched gestational age. Microbial state of amniotic cavity included culture for aerobic and anaerobic bacteria, mycoplasmas and ureaplasma whether or not clinical signs of chorioamnionitis were present. Maternal serum and amniotic fluid IL-1, IL-6, TNFalpha and IFNgamma concentrations were determined by the corresponding immunoradiometric assay, whereas EGF concentration was determined by a specific radioimmunoassay.

RESULTS

Nearly all cases of PROM with infection revealed elevated amniotic fluid cytokines (IL-1beta, IL-6, TNFalpha, IFNgamma, EGF) whereas half of them revealed elevated serum cytokines. In cases of PROM without confirmed infection, there were no significant changes of maternal serum cytokines, whereas two-thirds of them revealed elevated amniotic fluid cytokines.

CONCLUSIONS

The rise of cytokines in amniotic fluid of cases of PROM with infection may represent: (a) enhanced macrophage activity for immunosurveillance of the fetus; (b) a preparatory step for the initiation of labor; and (c) a valuable tests for diagnosing chorioamnioitis. The mechanism responsible for PROM in the presence or absence of infection is likely to be of different nature.

Intrauterine infection and prematurity

Intrauterine infection is a major cause of premature labor with and without intact membranes. Intrauterine infection is present in approximately 25% of all preterm births and the earlier the gestational age at delivery, the higher the frequency of intra-amniotic infection. Microorganisms may also gain access to the fetus before delivery. A fetal inflammatory response syndrome elicited in response to microbial products is associated with the impending onset of preterm labor and also with multi-systemic organ involvement in the human fetus and a higher rate of perinatal morbidity. The most common microorganisms involved in intrauterine infections are Ureaplasma urealyticum, Fusobacterium species and Mycoplasma hominis. The role of Chlamydia trachomatis and viruses in preterm labor remain to be determined. Use of molecular microbiology techniques to diagnose intrauterine infection may uncover the role of fastidious microorganisms that have not yet been discovered. Antibiotic administration to patients with asymptomatic bacteriuria is associated with a significant reduction in the rate of preterm birth. However, such benefit has not been demonstrated for patients with bacterial vaginosis, or women who carry Streptococcus agalactia, Ureaplasma urealyticum or Trichomonas vaginalis. Antibiotic administration to patients with preterm premature rupture of membranes is associated with prolongation of pregnancy and a reduction in the rate of clinical chorioamnionitis and neonatal sepsis. The benefit has not been demonstrated in patients with preterm labor and intact membranes. Major efforts are required to determine why some women develop an ascending intrauterine infection and others do not and also what interventions may reduce the deleterious effect of systemic fetal inflammation.

Amniotic fluid microflora in asymptomatic women at mid-gestation

The presence and composition of amniotic fluid (AF) microflora, as well as AF glucose concentration and white blood cell (WBC) count, were investigated in 22 consecutive asymptomatic women with intact membranes at mid-gestation. AF was retrieved by trans-abdominal amniocentesis. Three of the 22 women (13.6%) had microorganisms in their AF: Chlamydia trachomatis in 2 and both Corynebacterium group absolute nonfermenter (ANF) group and Propionibacterium spp. in 1. No differences were found in clinical characteristics, glucose concentration or WBC count in patients with and without microorganisms in their AF.

Sensitive identification of mycobacterial species using PCR-RFLP on bronchial washings

In 98 patients (24 with active pulmonary tuberculosis [TB] lesions, 28 with cured TB lesions, and 46 with nontuberculous opacities [control group] in chest CT scans), we examined whether washing the bronchus after brushing the lesion, then applying polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) to the bronchial washings might be useful for diagnosing TB and nontuberculous mycobacteriosis (NTMosis). After biopsy and brushing with a bronchoscope, the bronchus connecting to the lesion was washed with 20 ml saline. The saline used for washing the brushes (5 ml; brushing sample), and 3 to 10 ml saline aspirated through the forceps channel (washing sample) were examined by PCR-RFLP, which proved able to identify Mycobacterium tuberculosis and seven species of nontuberculous mycobacteria (NTM). The values obtained for the sensitivity of the PCR-RFLP with respect to the brushing sample, the washing sample, and both samples mixed together were 70, 76, and 91%, respectively, when only patients who were culture-positive or radiologically improved after antituberculous therapy were considered as showing true infection. A mixture of brushing and washing samples provides useful material for PCR and culture, and the PCR-RFLP used here is a good method for the simultaneous identification of several species of mycobacterium (including M. tuberculosis).