Amniotic fluid infection as determined by transabdominal amniocentesis in patients with intact membranes in premature labor

Amniotic fluid glucose and cytokines values in the early diagnosis of amniotic infection in patients with preterm labor and intact membranes

OBJECTIVE

Our goal was to compare sensitivity, specificity, and predictive values of glucose and cytokines [interleukin-1 (IL-1), interleukin-6 (IL-6), interleukin-8 (IL-8), and tumor necrosis factor (TNF)] in amniotic fluid (AF) to detect an AF-positive culture.

METHODS

Amniocentesis was performed on 113 patients with preterm labour (PTL) and intact membranes. Fluid was cultured for aerobic and anaerobic bacteria, and for mycoplasmas. AF analysis included cytokines and glucose determinations.

RESULTS

The prevalence of positive AF cultures was 11.5% (13/113). Anaerobic bacteria were isolated in 9 patients (69.2%). The glucose <16 mg/dl and cytokines values; IL-1 >640 pg/ml, IL-6 >55,000 pg/ml, IL-8 >1,000 pg/ml, TNF >672 pg/ml, were significantly correlated (P < 0.01) with AF culture result. Glucose had a sensitivity of 69.2% and a specificity of 96% for the prediction of positive AF culture. The sensitivity and specificity of the cytokines ranged from 61.5-53.4% and 79.8-8.99%, respectively.

CONCLUSIONS

In the diagnosis of the AF-positive culture, glucose <16 mg/dl is more sensitive than cytokines.

Preterm birth: associations with genital and possibly oral microflora

Opportunistic pathogenic microbes are indigenous to the female lower genital tract and etiologic in many types of pelvic infections and, apparently, a portion of preterm birth (PTB) cases. Bacterial vaginosis (BV) is a clinical syndrome based on an altered genital microflora in which Gardnerella vaginalis; anaerobic species primarily among Prevotella, Porphyromonas, Bacteroides, Peptostreptococcus, and Mobiluncus; Mycoplasma hominis; and Ureaplasma urealyticum become predominant in vaginal secretions. This BV complex of microbes, compared to a normal vaginal microflora dominated by facultative lactobacilli, is associated with significantly increased risks for preterm labor, preterm premature rupture of membranes, PTB, and other perinatal infectious complications. Pathogenetic mechanisms include an ascending route of infection and/or inflammatory process due to microbial products and maternal and/or fetal response(s) with production of prostaglandins and cytokines. In the presence of periodontal disease, oral opportunistic pathogens and/or their inflammatory products also may have a role in prematurity via a hematogenous route. Fusobacterium nucleatum, a common oral species, is the most frequently isolated species from amniotic fluid cultures among women with preterm labor and intact membranes. Also, the species and subspecies of fusobacteria identified from amniotic fluid most closely match those reported from healthy and diseased subgingival sites, namely F. nucleatum subspecies vincentii and F. nucleatum subspecies nucleatum, compared to strains identified from the lower genital tract. Although these fusobacteria also could be acquired through cunnilingus from a partner, new data associating maternal periodontal disease with preterm low birth weight taken with the isolation of F. nucleatum, Capnocytophaga, and other oral species from amniotic fluid support further study of a possible additional route, oral-hematogenous, to PTB.

Chorioamnionitis caused by gram-negative bacteria as an etiologic factor in preterm birth

The role and microbiological causes of infection and inflammation of the chorioamnion were studied in 85 patients with spontaneous preterm deliveries (< 37 weeks) and in 85 control patients with full term deliveries. Microorganisms were isolated from the freshly separated chorioamnion in 55% of preterm and 26% of term deliveries (p < 0.001). Isolation rates of gram-negative enteric bacteria were significantly higher in preterm deliveries than in term deliveries (p < 0.001), whereas differences in the isolation of other bacterial species were not significant. Histological chorioamnionitis was noted in 49% of preterm and 14% of term deliveries (p < 0.001), and was strongly associated with a positive chorioamniotic culture in both groups (p < 0.001). Histological chorioamnionitis was noted in 94%, 54%, and 4% of membranes with gram-negative rods, other microbial species and negative cultures, respectively (p < 0.001). Preterm deliveries were also associated with significantly higher rates of bacterial vaginosis (38% vs. 14%) and isolation of vaginal pathogens (85% vs. 65%). In the case of the majority (88%) of chorioamniotic isolates the same species was isolated in the vagina. The findings suggest that gram-negative enteric rods are important placental pathogens responsible for sub-clinical chorioamnionitis and possibly preterm birth. The findings support the concept that microorganisms ascending from the lower genital tract produce local inflammation, which may result in preterm labour and delivery.

Pathogenesis of preterm labor and preterm premature rupture of membranes associated with intraamniotic infection

We have proposed a model in which the initiation of human parturition in the presence of infection is controlled by the host. Systemic maternal infections such as pyelonephritis or localized infections such as deciduitis can trigger parturition by the activation of the monocyte and macrophage system in peripheral blood and human decidua. Preterm labor and preterm PROM can, according to this, be considered events that occur when the intrauterine or maternal environment is hostile and threaten the survival of the fetal-maternal pair. From this point of view, the initiation of preterm labor may have survival value. Why does intrauterine infection result in preterm labor in some cases and PROM in others? It is possible that regulation of different components of the host response has an important role to play in determining clinical presentation. Thus, if preferential activation of the host response leads to the secretion of uterotonic agents (i.e., prostaglandins), preterm labor will result. On the other hand, if the activation of the host response results predominantly in the production of proteases (i.e., leukocyte elastase and MMPs), patients are more likely to experience PROM. Preterm labor and preterm PROM can be considered expressions of the same basic phenomenon: activation of the host-defense macrophage system. Although we have provided evidence that infection is an important factor in the pathogenesis of these conditions, preterm parturition should be considered as a syndrome with multiple causes.

Obstetric antecedents of intraventricular hemorrhage and periventricular leukomalacia in the low-birth-weight neonate

OBJECTIVE

Neonatal intraventricular hemorrhage and periventricular leukomalacia have a strong correlation with eventual neurologic deficit. Our objective was to correlate obstetric factors with the development of these lesions.

STUDY DESIGN

Seven hundred forty-five consecutive inborn neonates with birth weights from 500 to 1750 gm were divided into three clinical groups: premature rupture of membranes, refractory preterm labor with intact membranes, and delivery initiated by the physician for maternal or fetal indications. Neonatal neurosonography was performed on days 3 and 7 of life and results were described as normal or abnormal. Abnormal scans included intraventricular hemorrhage seen within 3 days and echodense or echolucent periventricular leukomalacia seen within 7 days of life. Major abnormalities included intraventricular hemorrhage grades 3 and 4, intraventricular hemorrhage with periventricular leukomalacia, and echolucent periventricular leukomalacia. Abnormal scans were correlated with groups of origin and clinical and histologic chorioamnionitis.

RESULTS

Abnormal scans occurred in 33% of cases of premature rupture of membranes and in 38.9% of cases of preterm labor compared with 17.7% of physician-initiated cases (p < 0.000001). Major lesions occurred in 17.6% of cases of premature rupture of membranes, 21.4% of cases of preterm labor, and 1.1% of physician-initiated cases (p < 0.0000001). Clinical chorioamnionitis occurred in 19.7% of cases of premature rupture of membranes, 11.9% of cases of preterm labor, and 1.1% of physician-initiated cases (p < 0.001) and was associated with a significant increase in the incidence (p < or = 0.005) and severity (p < or = 0.007) of these lesions. Histologic chorioamnionitis occurred in 59.9% of cases of premature rupture of membranes, 43.2% of cases of preterm labor, and 8% of physician-initiated cases and did not correlate significantly with the incidence or severity of abnormal scans. These findings were independent of gestational age.

CONCLUSIONS

The incidence and severity of intraventricular hemorrhage and periventricular leukomalacia were significantly increased in premature rupture of membranes and preterm labor compared with the physician-initiated cases. Clinical chorioamnionitis increased the incidence and severity of these lesions.

A comparison of rapid amniotic fluid markers in the prediction of microbial invasion of the uterine cavity and preterm delivery

OBJECTIVE

The purpose of this study was to evaluate amniotic fluid lactate dehydrogenase level in comparison with other rapid markers in prediction of microbial invasion of the uterine cavity and preterm delivery < or = 36 hours after amniocentesis.

STUDY DESIGN

One hundred thirty-one women in preterm labor with intact membranes underwent transabdominal amniocentesis. Amniotic fluid was analyzed for leukocyte count, glucose level, lactate dehydrogenase level, and Gram stain. Cultures for aerobes, anaerobes, and Mycoplasma sp. were performed. Amniocentesis-to-delivery interval was calculated. The study group was divided and the findings compared according to amniotic fluid culture results and according to amniocentesis-to-delivery interval. Sensitivity, specificity, and positive and negative predictive value were calculated for lactate dehydrogenase, leukocyte count, glucose, and Gram stain in the prediction of positive amniotic fluid culture and preterm delivery < or = 36 hours after amniocentesis. Receiver-operator characteristic curve analysis, logistic regression analysis, t tests, and nonparametric tests were used.

RESULTS

The prevalence of positive amniotic fluid cultures was 12% (16 of 131). The median lactate dehydrogenase level (1084 U/L) was significantly greater for women with a positive amniotic fluid culture than for those with a negative culture (median lactate dehydrogenase level 194 U/L; p < 0.0002). The critical values calculated for optimal performance in prediction of a positive amniotic fluid culture were a lactate dehydrogenase level > or = 419 U/L, leukocyte count > or = 50 cells/mm3 (50 x 10(6)/L) and glucose < or = 17 mg/dl (0.94 mmol/L). Lactate dehydrogenase, leukocyte count, glucose, and Gram stain were equally sensitive and specific in prediction of a positive amniotic fluid culture. Thirty-nine women (29.8%) gave birth < or = 36 hours after amniocentesis. The median lactate dehydrogenase level (414 U/L) was significantly greater among women giving birth < or = 36 hours after amniocentesis than among women giving birth > 36 hours after amniocentesis (median lactate dehydrogenase, 173 U/L; p < 0.001). Critical values of lactate dehydrogenase > or = 225 U/L, leukocyte count > or = 10 cells/mm3 (10 x 10(6)/L) and glucose < or = 34 mg/dl (1.9 mmol/L) were selected for optimal performance in prediction of amniocentesis-to-delivery interval < or = 36 hours. Lactate dehydrogenase level had the best sensitivity (74%) in prediction of delivery < or = 36 hours after amniocentesis in contrast to leukocyte count (49%), glucose (62%), and positive Gram stain (26%). Amniotic fluid lactate dehydrogenase values > or = 225 U/L were associated with a fivefold greater risk for delivery < or = 36 hours after amniocentesis (odds ratio 5.46, 95% confidence interval 2.00 to 14.87; p = 0.0006).

CONCLUSION

Amniotic fluid lactate dehydrogenase level has diagnostic value in prediction of a positive amniotic fluid culture and delivery < or = 36 hours after amniocentesis. Lactate dehydrogenase is a readily available, inexpensive, rapid amniotic fluid marker that can be measured in any hospital laboratory.

Neonatal bacterial sepsis in a neonatal intensive care unit: a 5 year analysis

OBJECTIVE

To study the pattern of neonatal sepsis in a neonatal intensive care unit (NICU) during a 5 year period and assess the relationship between maternal risk factors and early onset sepsis (EOS).

METHODOLOGY

The study reported here was a retrospective analysis of 209 episodes of septicaemia and 5 episodes of bacterial meningitis in 198 newborn infants, 22 of whom died. Eighty-one infants had EOS (< or = 72 h) and 117 infants had late onset sepsis (LOS > 72 h). All infants had clinical evidence of sepsis, a computerized haematological score for sepsis of 4 or greater, and either treatment with antibiotics for 7 days or more or had earlier death due to sepsis. The organisms causing neonatal sepsis were analyzed according to the day of onset, gestational age, birthweight and year of infection.

RESULTS

Sepsis occurred in 5.6 per 1000 live births and 3.8% of NICU admissions. There were 81 episodes of EOS and 128 of LOS. Coagulase negative staphylococci (CONS) 38.8%, group B Streptococcus (GBS) 20.1% and Gram-negative bacilli (GNB) 20.1% were the common causes of sepsis; and GBS (50.6%) and CONS (60.9%) were the most common organisms in EOS and LOS, respectively. The mean gestational age and birthweight were higher in babies with EOS than compared with LOS. The higher likelihood of probable rather than definite infection in infants with EOS was related to more mothers in the EOS group receiving intrapartum antibiotics. GNB infection was more common in their babies.

CONCLUSIONS

GBS and CONS were the most common causes of EOS and LOS, respectively. The use of maternal intrapartum antibiotics interferes with neonatal blood culture results. Because blood cultures are not always positive in neonatal septicaemia, a combination of clinical, haematological and other microbiological evidence should be used when diagnosing neonatal septicaemia.

Reduced incidence of preterm delivery with metronidazole and erythromycin in women with bacterial vaginosis

BACKGROUND

Pregnant women with bacterial vaginosis may be at increased risk for preterm delivery. We investigated whether treatment with metronidazole and erythromycin during the second trimester would lower the incidence of delivery before 37 weeks' gestation.

METHODS

In 624 pregnant women at risk for delivering prematurely, vaginal and cervical cultures and other laboratory tests for bacterial vaginosis were performed at a mean of 22.9 weeks' gestation. We then performed a 2:1 double-blind randomization to treatment with metronidazole and erythromycin (433 women) or placebo (191 women). After treatment, the vaginal and cervical tests were repeated and a second course of treatment was given to women who had bacterial vaginosis at that time (a mean of 27.6 weeks' gestation).

RESULTS

A total of 178 women (29 percent) delivered infants at less than 37 weeks' gestation. Eight women were lost to follow-up. In the remaining population, 110 of the 426 women assigned to metronidazole and erythromycin (26 percent) delivered prematurely, as compared with 68 of the 190 assigned to placebo (36 percent, P = 0.01). However, the association between the study treatment and lower rates of prematurity was observed only among the 258 women who had bacterial vaginosis (rate of preterm delivery, 31 percent with treatment vs. 49 percent with placebo; P = 0.006). Of the 358 women who did not have bacterial vaginosis when initially examined, 22 percent of those assigned to metronidazole and erythromycin and 25 percent of those assigned to placebo delivered prematurely (P = 0.55). The lower rate of preterm delivery among the women with bacterial vaginosis who were assigned to the study treatment was observed both in women at risk because of previous preterm delivery (preterm delivery in the treatment group, 39 percent; and in the placebo group, 57 percent; P = 0.02) and in women who weighed less than 50 kg before pregnancy (preterm delivery in the treatment group, 14 percent; and in the placebo group, 33 percent; P = 0.04).

CONCLUSIONS

Treatment with metronidazole and erythromycin reduced rates of premature delivery in women with bacterial vaginosis and an increased risk for preterm delivery.

Bacterial vaginosis in pregnancy: an approach for the 1990s

It is proposed that clinicians screen all pregnant women at high risk for preterm labor and premature rupture of membranes for bacterial vaginosis, and treat all women when it is diagnosed. This infection is associated with a two to three times increase in preterm labor and delivery, premature rupture of the membranes, and endometritis. Although cause and effect have not been conclusively documented, these associations must be considered in the practice of obstetrics at the present. The paucity of vaginal Lactobacillus spp is pivotal in allowing overgrowth of many other organisms of the vagina. Screening is suggested because 50 percent of bacterial vaginosis is asymptomatic. The diagnosis, which is rapidly made and inexpensive, remains defined by clue cells seen on wet prep, high vaginal pH, and amine odor of the vaginal discharge. Optimal treatment of pregnant women with bacterial vaginosis is via oral or intravaginal metronidazole or clindamycin.

Ureaplasma urealyticum chorioamnionitis

Controversy reigns over the role of Ureaplasma urealyticum in determining pregnancy outcome. U. urealyticum infection of the chorioamnion is strongly associated with chorioamnionitis (1-3), premature birth (2-4), and perinatal morbidity (4-6). We present 4 cases of U. urealyticum chorioamnionitis and associated morbidity and mortality.

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

OBJECTIVE

The purpose of this study was to evaluate the ability of a low amniotic fluid glucose level, as defined by previously published thresholds, to identify a subclinical intrauterine infection in women in preterm labor with intact membranes.

STUDY DESIGN

Amniotic fluid glucose levels, amniotic fluid cultures, and placental histologic characteristics were determined in women with preterm labor (n = 55) and in preterm controls (n = 58). These amniotic fluid glucose levels were compared between women with and without intrauterine infection using the Mann-Whitney U test. The sensitivity, specificity, and positive and negative predictive values for the identification of an intrauterine infection were determined with four different previously published amniotic fluid glucose threshold levels and the threshold from receiver-operator characteristic curve analysis of the study data.

RESULTS

The median amniotic fluid glucose level was significantly lower in patients with positive amniotic fluid cultures (intraamniotic infection group) but was not lower in the group of patients with only histologic chorioamnionitis (extra-amniotic infection group), compared with noninfected controls. The sensitivity of a low amniotic fluid glucose level to detect both types of intrauterine infection ranged from 41% to 55%, depending on the threshold used. The specificity of a low amniotic fluid glucose level to detect an intrauterine infection ranged from 94% to 100%, the positive predictive value ranged from 86% to 100%, and the negative predictive value ranged from 70% to 80% with the same thresholds.

CONCLUSION

Low amniotic fluid glucose levels are a specific but not a sensitive marker for either intraamniotic or extra-amniotic intrauterine infections in patients with preterm labor.

Eradication of Viridans streptococci from the amniotic cavity with transplacental antibiotic treatment

We report a case of eradication of Viridans streptococci from the amniotic cavity in a patient with preterm labor and intact membranes by transplacental antibiotic treatment. Following this modality of treatment, preterm labor was arrested and the pregnancy continued uneventfully until normal term delivery. We suggest that transplacental antibiotic treatment should be seriously considered as part of the medical armamentarium for treatment of patients with preterm labor and microbial invasion of the amniotic cavity.

Urinary tract infection during pregnancy: its association with maternal morbidity and perinatal outcome

OBJECTIVES

The effects of antepartum urinary tract infection on adverse maternal and perinatal outcomes were examined. Antepartum urinary tract infection has been previously implicated as a risk factor for numerous outcomes.

METHODS

Crude and multivariable analyses were performed with a perinatal registry cohort of 25,746 mother/infant pairs.

RESULTS

Elevated risks were observed for exposure to urinary tract infection and low birthweight, prematurity, preterm low birthweight, premature labor, hypertension/preeclampsia, maternal anemia, and amnionitis. Urinary tract infection was associated with perinatal death only among subjects 20 to 29 years of age.

CONCLUSIONS

These findings underscore the importance of antepartum urine screening to identify patients at risk for adverse outcomes.

Amniotic fluid interleukin-6 levels correlate with histologic chorioamnionitis and amniotic fluid cultures in patients in premature labor with intact membranes

OBJECTIVES

Our purpose was (1) to determine the frequency of intraamniotic and extraamniotic intrauterine infection in patients with premature labor and intact membranes and (2) to determine if intrauterine infection is associated with elevated amniotic fluid interleukin-6 levels.

STUDY DESIGN

Amniocentesis was performed on 57 patients in preterm labor and 201 controls at various gestational ages without labor and at term with labor. The amniotic fluid was evaluated with gram stain, cultures, and an enzyme-linked immunosorbent assay specific for interleukin-6. Placentas from study patients (n = 52) and term controls (n = 120) were analyzed.

RESULTS

The frequency of positive amniotic fluid cultures (intraamniotic intrauterine infection) was 10 of 57 (18%) in the preterm labor group and zero of 201 for controls. Histologic chorioamnionitis (extraamniotic intrauterine infection) was present in 21 of 24 (88%) of patients in preterm labor that failed tocolysis and 28 of 120 (23%) of term laboring controls. An amniotic fluid interleukin-6 level of > or = 600 pg/ml was 100% sensitive and 89% specific (positive predictive value 85%, negative predictive value 100%) for the identification of intrauterine infection.

CONCLUSION

Interleukin-6 is a sensitive and specific marker for the identification of both intraamniotic and extraamniotic intrauterine infection in patients in preterm labor with intact membranes.

Amniotic fluid interleukin-6 determinations are of diagnostic and prognostic value in preterm labor

PROBLEM

The purpose of this study was to determine if amniotic fluid concentrations of the interleukin-6 (IL-6) are of value in diagnosis of microbial invasion of the amniotic cavity and in the prediction of failure of tocolysis, preterm delivery and perinatal morbidity and mortality.

METHOD

Amniotic fluid was obtained by transabdominal amniocentesis from 146 consecutive patients admitted with the diagnosis of preterm labor and intact membranes. Fluid was cultured for aerobic and anaerobic bacteria as well as for mycoplasmas. Amniotic fluid IL-6 levels were measured using a monoclonal antibody-based enzyme-linked immunosorbent assay with a sensitivity of 0.03 ng/ml. Logistic regression and Cox's proportional hazards model were used to examine the effect of several variables on dichotomous outcomes or interval to delivery.

RESULTS

Patients with a positive amniotic fluid culture had a significantly higher amniotic fluid IL-6 concentrations than patients with a negative culture (median 91.2 ng/ml, range 0.9 to 437 ng/ml versus median 0.4 ng/ml, range < 0.3 to 195 ng/ml, respectively; P < .0001). An amniotic fluid IL-6 concentration of greater than or equal to 11.3 ng/ml had a sensitivity of 93.3% (14 of 15) and a specificity of 91.6% (120 of 131). All patients with an amniotic fluid IL-6 concentration above 11.3 ng/ml and a negative amniotic fluid culture (N = 11) delivered preterm and all placenta available for examination (N = 7) had histologic evidence of chorioamnionitis. Amniotic fluid concentrations of IL-6 were an independent predictor of preterm delivery, amniocentesis-to-delivery interval and neonatal morbidity and mortality. Moreover, IL-6 concentrations added significant information to the prediction of these outcomes to that provided only by clinical information such as cervical dilatation, gestational age at admission or at delivery.

CONCLUSION

IL-6 is a sensitive and rapid test for the detection of microbial invasion of the amniotic cavity and for identifying women at risk for spontaneous preterm delivery and neonates at risk for morbidity and mortality.

Ureaplasma urealyticum intrauterine infection: role in prematurity and disease in newborns

Ureaplasma urealyticum, a common commensal of the urogenital tract of sexually mature humans, is gaining recognition as an important opportunistic pathogen during pregnancy. While its etiologic significance in many aspects of adverse pregnancy remains controversial, recent evidence indicates that U. urealyticum in the absence of other organisms is a cause of chorioamnionitis. Furthermore, ureaplasmal infection of the chorioamnion is significantly associated with premature spontaneous labor and delivery. In at least some cases, it appears to be causal. Present evidence indicates that U. urealyticum is a cause of septicemia, meningitis, and pneumonia in newborn infants, particularly those born prematurely. There is strong but not definitive evidence that ureaplasmal infection of the lower respiratory tract can lead to development of chronic lung disease in very low-birth-weight infants. Although risk factors for colonization of the lower genitourinary tract have been identified, little information is available concerning risk factors for intrauterine infection and host immune responses to invasive infection. Recent establishment of animal models of respiratory and central nervous system diseases should provide an opportunity to evaluate risk factors, pathogenic mechanisms, and operative immune mechanisms. However, the most critical need is additional information concerning indications for diagnosis and treatment as well as efficacy of treatment.

Inhibition of binding of bacteria to amniochorionic membranes by amniotic fluid

The immunological composition of amniotic fluids is shown to be of such a lower order of activity that its role in fetal protection may be limited. Also, amniotic fluids were found not to have classical antibiotic activity. Amniotic fluids (25/31), however, were found to inhibit, by 27.5% to 88.2%, three target bacteria from binding to discs of amniochorionic membranes. This inhibition is also demonstrable with the monosaccharides alpha-D(+)-fucose, D(+)-galactose, alpha-D-glucose, alpha-D-lactose and bovine serum albumin-lactose conjugate, whereas other glycoconjugates enhanced bacterial binding. This demonstrates that the test bacteria bind to the amniochorionic membranes using bacterial lectins. In intraamniotic infection bacterial lectins may be complexed by amniotic fluid glycoconjugates which prevent the bacteria from binding to the amniochorionic membranes. This would explain asymptomatic infection and in the absence or reduced levels of the glycoconjugates the bacteria would bind to the amniochorionic membranes giving rise to symptomatic infection.

A review of premature birth and subclinical infection

Premature birth causes high rates of neonatal morbidity and mortality. There are multiple causes of preterm birth. This article reviews the evidence linking subclinical infection and premature birth. Although maternal genital tract colonization with specific organisms has been inconsistently associated with preterm birth and/or premature rupture of membranes, some infections have been consistently associated with preterm delivery. The association of histologic chorioamnionitis with prematurity is a consistent finding, but the mechanisms require further study. The relationship between histologic chorioamnionitis infection and the chorioamnionitis of prematurity requires additional research. A varying number of patients in "idiopathic" preterm labor have positive amniotic fluid cultures (0% to 30%), but it is not clear whether infection preceded labor or occurred as a result of labor. Evidence of subclinical infection as a cause of preterm labor is raised by finding elevated maternal serum C-reactive protein and abnormal amniotic fluid organic acid levels in some patients in preterm labor. Biochemical mechanisms for preterm labor in the setting of infection are suggested by both in vitro and in vivo studies of prostaglandins and their metabolites, endotoxin and cytokines. Some, but by no means all, antibiotic trials conducted to date have reported decreases in prematurity. These results support the hypothesis that premature birth results in part from infection caused by genital tract bacteria. In the next few years, research efforts must be prioritized to determine the role of infection and the appropriate prevention of this cause of prematurity.

The relation between amniotic fluid surfactant concentration in preterm labour and histological evidence of chorioamnionitis

Concentration of amniotic fluid disaturated phosphatidylcholine (DSPC), factors related to cervical ripening, and histopathological evidence of chorioamnionitis were studied in 38 patients in preterm labour with intact membranes; all of them delivered spontaneously before 37 weeks. There was no correlation between the amniotic fluid DSPC level and gestational age at the time of amniocentesis. However, a significant inverse correlation was found between the amniotic fluid DSPC level and the interval between the onset of labour and delivery. The amniotic fluid DSPC level in cases with onset-delivery interval of less than 48 h was significantly higher than that in cases with an onset-delivery interval of 48 h or more. The gestational age in the former group was significantly lower than in the latter (28.6 vs 32.0 weeks). The amniotic fluid DSPC level in the patients with chorioamnionitis was significantly higher than that in the patients without chorioamnionitis, although the gestational age did not differ between the two groups. All 3 infants with RDS were associated with cervical incompetence. Patients in preterm labour with chorioamnionitis may be refractory to tocolysis and have higher amniotic fluid surfactant levels.

The prevalence and clinical significance of intraamniotic infection with Candida species in women with preterm labor

Intraamniotic infection is considered a major etiologic factor of preterm birth. Positive amniotic fluid cultures are rarely contaminated with Candida species. The presence of this microorganism is associated with a poor pregnancy outcome. Out of 773 transabdominal amniocenteses performed in women presenting with preterm labor and intact membranes, 77 patients (9.9%) had positive amniotic fluid cultures and in 5 women (6.5%) Candida species were identified. On the other hand, 625 amniocenteses were performed in women with preterm premature rupture of membranes and 178 (28%) had positive cultures. Only in 4 patients was Candida isolated (2.2%) (P = 0.13 Fisher's exact test). The importance of early and accurate diagnosis of intraamniotic infection with Candida is pointed out. A transabdominal amniocentesis for microbiological examination is suggested for every woman presenting with preterm labor or preterm premature rupture of membranes and especially for those who conceived with a retained IUD or cervical cerclage.

Infection and labor. VII. Microbial invasion of the amniotic cavity in spontaneous rupture of membranes at term

OBJECTIVE

The purpose of this study was to determine the frequency, microbiologic characteristics, and clinical significance of microbial invasion of the amniotic cavity in women with premature rupture of membranes at term.

STUDY DESIGN

Amniocentesis was performed in 32 women with term premature rupture of membranes and amniotic fluid cultured for aerobic and anaerobic bacteria and Mycoplasmas.

RESULTS

The prevalence of positive amniotic fluid cultures was 34.3% (11/32). The most common isolates were Ureaplasma urealyticum, Peptostreptococcus sp., Lactobacillus sp., Bacteroides fragilis, and Fusobacterium sp. Clinical chorioamnionitis occurred only in one patient with a positive amniotic fluid culture. Her neonate had ophthalmitis. Three patients (9.4%) had endometritis. Among women who were delivered vaginally, those with a positive amniotic fluid culture had a significantly higher rate of endometritis than those with a negative culture (33% [3/9] vs 0% [0/20], respectively, p = 0.023).

CONCLUSIONS

These data indicate that microbial invasion of the amniotic cavity occurs in approximately one third of patients with preterm premature rupture of membranes. Microbial invasion of the amniotic cavity is a risk factor for endometritis in women with term premature rupture of membranes.

Correlation of amniotic fluid glucose concentration and intraamniotic infection in patients with preterm labor or premature rupture of membranes

Amniotic fluid glucose concentration has previously been suggested as a rapid and sensitive test for diagnosing intraamniotic infection. In this study, 204 patients less than or equal to 34 weeks estimated gestational age with preterm labor or premature rupture of membranes underwent amniocentesis to detect subclinical intraamniotic infection. Amniotic fluid was cultured for aerobic and anaerobic bacteria, as well as for Mycoplasma species. Amniotic fluid glucose levels were significantly lower in patients with positive amniotic fluid cultures than in patients with negative cultures (median, 10 mg/dl; range, 1 to 62 mg/dl vs median, 31 mg/dl; range, 2 to 126 mg/dl, respectively; p less than 0.001). In terms of predicting amniotic fluid culture results, an amniotic fluid glucose concentration of less than or equal to 16 mg/dl had a sensitivity of 79%, specificity of 94%, positive predictive value of 87%, and negative predictive value of 90%. The determination of amniotic fluid glucose concentration is useful in detecting subclinical intraamniotic infection in patients less than or equal to 34 weeks estimated gestational age with preterm labor or premature rupture of membranes.

Amniotic fluid white blood cell count: a rapid and simple test to diagnose microbial invasion of the amniotic cavity and predict preterm delivery

The purpose of this study was to determine the value of amniotic fluid white blood cell count in the diagnosis of microbial invasion of the amniotic cavity. Amniotic fluid was retrieved by amniocentesis from 195 patients with preterm labor and intact membranes. Fluid was cultured for aerobic and anaerobic bacteria, as well as for mycoplasmas. The prevalence of a positive amniotic fluid culture was 12.8% (25/195). Patients with a positive amniotic fluid culture had a significantly higher median amniotic fluid white blood cell count than did patients with a negative amniotic fluid culture (median, 6 cells/mm3; range, 0 to 11,000 cells/mm3 vs median, 320 cells/mm3; range, 1 to 4480 cells/mm3; p less than 0.0001). An amniotic fluid white blood cell count greater than or equal to 50 cells/mm3 had a sensitivity of 80% (20/25), a specificity of 87.64% (149/170), a positive predictive value of 48.78% (20/41), and a negative predictive value of 96.75% (149/154) in the detection of a positive amniotic fluid culture for microorganisms. Although the sensitivity of an amniotic fluid white blood cell count (greater than or equal to 50 cells/mm3) in the detection of microbial invasion of the amniotic cavity was greater than that of the Gram stain of amniotic fluid (80% [20/25] vs 48% [12/25]; p less than 0.05), the specificity was lower (87.64% [149/170] vs 98.8% [168/170]; p less than 0.05). However, 88% (15/17) of all patients with an amniotic fluid white blood cell count greater than or equal to 50 cells/mm3 and a negative amniotic fluid culture had a spontaneous preterm delivery. We conclude that the amniotic fluid white blood cell count is a sensitive, simple, and inexpensive test for the detection of microbial invasion of the amniotic cavity. An elevated amniotic fluid white blood cell count is a risk factor for preterm delivery.

Amniotic fluid glucose and intraamniotic infection

Thirty-nine patients with either premature labor and/or preterm premature ruptured membranes underwent transabdominal amniocentesis to enable the following amniotic fluid analyses to be performed: culture and sensitivity, Gram's stain, and glucose determination. All nine patients with intraamniotic infection had amniotic fluid glucose values less than 10 mg/dl. Three patients with amniotic fluid glucose levels less than 10 mg/dl but without chorioamnionitis were delivered of infants within 72 hours of admission. The mean amniotic fluid glucose level of patients with intraamniotic infection (5 +/- 2.4 mg/dl) was significantly lower than in those without intraamniotic infection (39.8 +/- 18.42 mg/dl). All patients with amniotic fluid glucose values less than 10 mg/dl had either bacteria and/or white blood cells on Gram's stain. Two patients without chorioamnionitis had white cells on Gram's stain and amniotic fluid glucose values greater than 10 mg/dl. It appears that amniotic fluid glucose is more sensitive and more specific than Gram's stain in the diagnosis of intraamniotic infection. All 12 patients with low amniotic fluid glucose values were delivered of infants within 72 hours as the result of either the presence of infection or the progression of labor.

Intraamniotic infection in the very early phase of the second trimester

A total of 157 consecutive patients were studied in an effort to examine prospectively the incidence of asymptomatic intraamniotic infection in the early phase of the second trimester. All patients were referred for amniotic fluid karyotyping. In addition, the amniotic fluids were examined for Gram stain and were directly cultured on blood agar and MacConkey agar as well as in thioglycollate broth. We found positive amniotic fluid cultures in eight cases (5.09%); however, results of Gram stain examinations were negative in all amniotic fluid samples. The data indicate that there is no correlation between white blood cells in the amniotic fluid and positive amniotic fluid culture results. Only one pregnancy with positive amniotic fluid culture resulted in a septic abortion. Therefore we can suggest that intraamniotic infection can exist early in pregnancy, even with intact membranes, and in most cases without any clinical symptoms.

Infection and labor. VI. Prevalence, microbiology, and clinical significance of intraamniotic infection in twin gestations with preterm labor

The purpose of this study was to establish the prevalence, microbiology, and outcome of microbial invasion of the amniotic cavity in twin gestation presenting with preterm labor and intact membranes. Amniocenteses were performed on both sacs of 46 women with twin gestations, preterm labor, and intact membranes. Indigo carmine was injected to ensure sampling of both amniotic sacs. Amniotic fluid was cultured for aerobic and anaerobic bacteria, Mycoplasma hominis, and Ureaplasma urealyticum. A positive amniotic fluid culture of at least one sac was noted in 10.8% (5/46) of patients admitted in preterm labor and in 11.9% (5/42) of women delivered of preterm neonates. Of the five patients with microbial invasion of the amniotic cavity, three had microorganisms isolated from both sacs. The presenting sac was involved in all cases, supporting an ascending route for microbial invasion of the amniotic cavity in twin gestation. Polymicrobial infection was found in three of the eight amniotic sacs with positive cultures. In two cases different organisms were isolated from each sac. All patients with positive amniotic fluid cultures were delivered of preterm infants within 48 hours of amniocentesis. Patients with positive amniotic fluid cultures presented with preterm labor at an earlier gestational age and with more advanced cervical dilatation than did women with negative amniotic fluid cultures. Clinical evidence of chorioamnionitis subsequently developed in two of five women with positive amniotic fluid cultures. The interval between amniocentesis and delivery was shorter in women with positive amniotic fluid cultures than in women with negative amniotic fluid cultures (median: 3.5 vs 168 hours, p less than 0.0001). Infants born to women with microbial invasion of the amniotic cavity had a lower median birth weight and a higher incidence of respiratory distress syndrome than those born to women with negative amniotic fluid cultures (birth weight: 1085 vs 1975 gm, p = 0.024; respiratory distress syndrome: 37.5% vs 8.3%, p = 0.04).

C-reactive protein in preterm premature rupture of the membranes

The usefulness of maternal C-reactive protein (CRP) measurements in the diagnosis of chorioamnionitis and puerperal and neonatal infectious morbidity was studied among 147 patients with preterm rupture of the membranes (PROM). Thirty-three patients developed chorioamnionitis, 10 patients developed puerperal endometritis, and 21 newborn infants developed neonatal infections. There was no difference in the highest antepartum CRP between patients with or without chorioamnionitis. The overall test performance for CRP was poor suggesting that elevated antepartum CRP may be misleading in the diagnosis of chorioamnionitis. However, use of serial CRP measurements increases the test performance. The high negative predictive value suggests that CRP is useful in predicting the absence of chorioamnionitis.

The role of bacterial vaginosis as a cause of amniotic fluid infection, chorioamnionitis and prematurity--a review

Antepartum bacterial vaginosis in pregnancy has been related to premature delivery, the recovery of microorganisms from amniotic fluid of women in premature labor with intact membranes, to histologic chorioamnionitis and to the recovery of microorganisms from the placenta or membranes. Microorganisms associated with bacterial vaginosis are commonly recovered from the amniotic fluid and chorioamnion of patients who deliver prematurely. In addition, bacterial vaginosis is associated with maternal infectious morbidity during labor and in the postpartum period. Very little is known of the pathophysiologic mechanisms by which bacterial vaginosis may cause preterm labor and/or premature rupture of the membranes. However, it is of interest to speculate on possible mechanisms. The high concentration of potentially pathogenic microorganisms in the vagina and cervix of pregnant women with bacterial vaginosis may increase the possibility of an ascending infection via the cervix, decidua, fetal membranes, maternal placenta, and amniotic fluid. Some of the bacteria associated with bacterial vaginosis such as Bacteroides sp. are particularly virulent. Certain bacteria produce enzymes that potentially could affect the fetal membranes or maternal deciduae. Bacteroides sp. and group B streptococcus produce proteases. Protease enzymes reduce the chorioamniotic membrane strength in vitro. It is even possible that a high concentration of bacteria in the lower genital tract could produce enough proteases to weaken the fetal membrane strength causing premature rupture of the membranes. Bacterial lipases could also produce tissue injury. Schwarz et al. demonstrated that lysosomes within fetal membrane cells contain phospholipase A2 in high concentrations. Phospholipase A2 is a precursor of prostaglandin synthesis and the destruction of lysosomes within deciduae or chorioamnion cells may induce prostaglandin synthesis resulting in uterine contractions. Bejar et al. found a high rate of phospholipase A2 production by Bacteroides sp., anaerobic streptococci, Fusobacterium sp., and G. vaginalis. Benett et al. demonstrated that bacterial products of group B streptococci, viridans streptococci, Escherichia coli and Bacteroides fragilis but not of Lactobacillus sp. increase the synthesis of prostaglandins in the membranes. Thus, selected bacteria, including some closely related to bacterial vaginosis may play a role in the initiation of uterine contractions by stimulating prostaglandin synthesis. In an alternative mechanism, either the release of prostaglandin in the membrane or uterine contraction could cause microbreaks of the membrane that allow bacterial colonization of the membrane.(ABSTRACT TRUNCATED AT 400 WORDS)

Subclinical amnionitis in patients with intact membranes in preterm labour

Preterm delivery is the major obstetric and paediatric problem, being responsible for much perinatal morbidity and mortality. Subclinical amnionitis may cause preterm labour and delivery. The rate of subclinical bacterial infection of amniotic fluid was studied in 25 afebrile pregnant women with intact membranes in preterm labour. Specimens of amniotic fluid were collected by transabdominal amniocentesis. Serum and amniotic fluid lactic dehydrogenase (LDH) levels were assessed to determine their usefulness in making the diagnosis of subclinical amnionitis. Aerobic bacteria were isolated from 48% (12/25) of the specimens. Thus, subclinical amnionitis may play a substantial role in patients with intact membranes in preterm labour. However, transabdominal amniocentesis is not routinely indicated in similar asymptomatic patients because microbiological and especially LDH studies require further evaluation.

The incidence of positive amniotic fluid cultures in patients preterm labor with intact membranes

The possible relationship between intrauterine infection and preterm labor has received considerable attention in recent years. The purpose of this study was twofold: first, to determine the frequency of asymptomatic infection in patients who came to the hospital in preterm labor, and second, to determine the significance of a positive amniotic fluid culture in relation to latency period and likelihood of preterm delivery. Patients who came to the hospital in preterm labor with intact membranes between 20 and 35 weeks' gestation underwent transabdominal amniocentesis. Amniotic fluid was sent for Gram stain and culture. Patients received tocolytic therapy as clinically indicated. Of 127 patients cultured, seven (5.5%) had positive amniotic fluid cultures. These patients had a significantly decreased latency period from amniocentesis to delivery (4.4 days versus 28.6 days), and a significantly increased chance of being delivered of preterm infants (100% versus 52.5%), as compared with patients with negative cultures. The rate of positive Gram stain was 7 of 125 positive. However, there was no correlation between positive Gram stain and positive culture results. Similarly, positive Gram stain results were not associated with any difference in the latency period or rate of preterm delivery.

Infection and labor. V. Prevalence, microbiology, and clinical significance of intraamniotic infection in women with preterm labor and intact membranes

Amniotic fluid was retrieved by amniocentesis from 264 patients with preterm labor and intact membranes admitted to Yale-New Haven Hospital from Jan. 1, 1985, to July 31, 1988. The prevalence of a positive amniotic fluid culture was 9.1% (24/264). A total of 111 patients (42%) delivered preterm neonates, and 24 (21.6%) of those had positive amniotic fluid cultures. The diagnostic indexes of the Gram stain of amniotic fluid in the prediction of a positive amniotic fluid culture were as follows: sensitivity, 79.1%; specificity, 99.6%; positive predictive value, 95%; and negative predictive value, 98%. Endotoxin was detected with the limulus amebocyte lysate assay in 4.9% (13/264) of patients with preterm labor. All patients with endotoxin in the amniotic fluid delivered preterm neonates. The three most frequently isolated organisms were Ureaplasma urealyticum (n = 6), Fusobacterium species (n = 5), and Mycoplasma hominis (n = 4). Clinical chorioamnionitis was present in only 12.5% of the patients with positive amniotic fluid cultures. Women with positive amniotic fluid cultures had lower gestational ages and more advanced cervical dilatation on admission than women with negative cultures. Preterm infants born to mothers with positive amniotic fluid cultures had a higher incidence of respiratory distress syndrome and infectious complications than preterm neonates born after negative amniotic fluid cultures. These data underscore the frequency and importance of intraamniotic infections in women with preterm labor.

C-reactive protein in preterm labour: association with outcome of tocolysis and placental histology

Tocolytics were administered in 66 consecutive women in uncomplicated preterm labour with intact fetal membranes (53 singleton and 13 twin pregnancies). C-reactive protein (CRP), a marker of infection, was determined daily and used retrospectively to investigate the role of subclinical infection in preterm labour and to predict the efficacy of tocolysis and the development of a clinical perinatal infection. CRP was also determined in 66 women in uncomplicated labour at term (53 singleton and 13 twin pregnancies). The placenta was examined for histological evidence of infection in all patients who were delivered before 36 weeks (n = 21) and in all women in the control group (n = 66). Elevated CRP levels were more often found in patients who were refractory to tocolysis, suggesting an underlying infectious morbidity. Placental infection was found in 62% of the preterm delivery group and in 12% of the control group. There was an association between elevated CRP levels and histological evidence of placental infection. However, confounding factors such as urinary tract infections limit the usefulness of the CRP test. Because CRP cannot predict clinical perinatal infection accurately, its clinical relevance is very limited.

Cachectin/tumor necrosis factor-alpha formation in human decidua. Potential role of cytokines in infection-induced preterm labor

This study was conducted as part of an investigation to evaluate the hypothesis that bacterial toxins (LPS or lipoteichoic acid), acting on macrophage-like uterine decidua to cause increased formation of cytokines, may be involved in the pathogenesis of infection-associated preterm labor. We found that cachectin/tumor necrosis factor-alpha (TNF-alpha) was synthesized and secreted into the culture medium by human decidual cells and explants in response to treatment with LPS. LPS treatment also caused an increase in PGF2 alpha production by decidual cells and explants. In amnion cells in monolayer culture, TNF-alpha stimulated PGE2 formation, and TNF-alpha was cytostatic (inhibited [3H]thymidine incorporation into DNA) but not cytolytic in amnion cells. TNF-alpha was not detectable (less than 0.34 ng/ml) in the amniotic fluid of normal pregnancies at midtrimester or at term before or after the onset of labor (n = 44); but TNF-alpha was present at concentrations between 2.8 and 22.3 ng/ml in amniotic fluids of 4 of 20 pregnancies with intact membranes complicated by preterm labor (less than 34 wk gestational age). LPS was present in 10 of the 20 amniotic fluids of preterm labor pregnancies, including all four in which TNF-alpha was present. Bacteria were identified in only one of the four LPS-positive, TNF-alpha-positive fluids. Cytokine formation in macrophage-like decidua may serve a fundamental role in the pathogenesis of preterm labor, including increased prostaglandin formation and premature rupture of the membranes.

Amniotic fluid prostaglandin E2 in preterm labor

These studies were designed to determine amniotic fluid concentrations of prostaglandin E2 (PGE) in women with preterm labor. Amniotic fluid was retrieved by transabdominal amniocentesis from 68 women with preterm labor (less than 37 weeks). Patients were divided into three groups according to the response to tocolysis and the presence or absence of an intraamniotic infection. Amniotic fluid concentrations of PGE2 were significantly greater in women with preterm labor and intraamniotic infection than in women without infection. Patients unresponsive to tocolysis without intraamniotic infection had a significantly greater concentration of PGE2 in amniotic fluid than those responsive to tocolysis.

Clinical effectiveness of a new cervical indwelling catheter in the management of premature rupture of the membranes: a Japanese collaborative study

The aim of this multiinstitutional study was to evaluate a new cervical indwelling catheter in 84 patients with premature rupture of the membranes at less than 33 weeks' gestation. The average time of insertion of the catheter was 29.1 weeks' gestation, at an average of 2.0 days after rupture, and was left in place for an average of 6.5 days. The mean birth weight was 1417 gm. The mortality rate and the incidence of respiratory distress syndrome were 5.7% and 11.9%, respectively. Amniotic fluid culture was positive in 39.1% of patients before catheter insertion and only 4.3% at the time of delivery. Infection was noted in only four of 84 infants. The incidence of infection was very low in those treated for 3 days or more after catheter insertion.

Amniotic fluid 5-hydroxyeicosatetraenoic acid in preterm labor

5-Hydroxyeicosatetraenoic acid (5-HETE) is an arachidonate lipoxygenase product capable of stimulating human uterine contractility in a dose-dependent manner in vitro. The purpose of this study was to determine if preterm labor is associated with changes in the concentration of this metabolite in amniotic fluid. Amniotic fluid was obtained by transabdominal amniocentesis from three groups of women with preterm labor: group 1 - women without intraamniotic infection who responded to tocolysis (n = 32); group 2 - women without intraamniotic infection who failed to respond to tocolysis (n = 22); and group 3 - women with intraamniotic infection (n = 14). 5-HETE was determined by radioimmunoassay. The median amniotic fluid concentration of 5-HETE in women who responded to tocolysis (median = 1412 pg/ml; range: 111-3547) was significantly lower than in women who delivered despite tocolysis (median = 2052 pg/ml; range: 136-7774) and women with intraamniotic infection (median = 1876 pg/ml; range: 543-7033) [p less than 0.05]). No difference in amniotic fluid concentrations' of 5-HETE were found between women in groups 2 and 3 (p greater than 0.05).

Preterm birth and infection: pathogenic possibilities

Preterm delivery remains the preeminent problem in perinatal care worldwide. Recent data suggest that cervical/vaginal microflora, and/or the inflammatory responses they engender, produce factors which can cause or predispose to preterm labor and rupture of membranes. Microorganisms mediating such processes may not be "recognized pathogens" and are often considered normal flora. These microorganisms may act singly, additively, or synergistically with host factors released during an induced inflammatory response. Both qualitative and quantitative aspects of cervical/vaginal microflora are likely important. Multiple cervical/vaginal microorganisms produce IgA proteases, neuraminidases, and mucinases which may facilitate passage of these and other agents past cervical barriers and into the lower uterine segment. Multiple microflora also produce phospholipases A2 and C, each of which can locally augment production of eicosanoids within the uterus which are important in cervical ripening and labor. Similar microflora produce various proteases, including collagenase, which can focally weaken the amniochorion and predispose to premature rupture of membranes and cervical ripening. Intrauterine microorganisms induce inflammatory reaction and may engender local release of similar proteases, phospholipases, oxygen radicals, as well as platelet activating factor (PAF), and lymphokines which can also initiate or further potentiate labor-inducing mechanisms. Roles for uteroplacental or systemic release of tumor necrosis factor (TNF) and various interferons are beginning to be understood. Recognition of microbe-induced pathogenesis of some cases of preterm birth offers the hope of specific treatment and prophylaxis. In recent studies, administration of erythromycin and tocolytic agents was associated with an improved outcome in selected women. "Just why so many gravidas go into labor prematurely and hence give birth to infants who often are unable to cope with extrauterine conditions is one of the great unsolved problems of obstetrics."

Capnocytophaga species: a cause of amniotic fluid infection and preterm labour

Subclinical amniotic fluid infection and subsequent preterm labour may occur with intact membranes. We report two cases of subclinical amniotic fluid infection with intact membranes presenting in preterm labour. Capnocytophaga species, fastidious Gram-negative bacilli normally found in oral flora, were isolated in pure culture from amniotic fluid obtained by transabdominal amniocentesis. The distinctive microbiological features and spectrum of infections associated with Capnocytophaga species, and the importance of recognition of subclinical amniotic fluid infection as a cause of preterm labour, are discussed.

Transcervical amnioinfusion of antibiotics: a basic study for managing premature rupture of membranes

To determine the best method of preventing ascending infection in the management of premature rupture of membranes, antibiotics such as latamoxef sodium, cefoperazone sodium, and cefotaxime sodium were infused directly into the amniotic cavity in 64 patients undergoing induction of labor at term. A single infusion of 100 or 500 mg of each drug resulted in a concentration of 200 to 1000 micrograms/ml immediately after infusion, and the concentration remained above 10 micrograms/ml for about 24 hours without significant increase in fetal or maternal blood levels. Consequently, a daily single dose of 100 mg or more is probably effective prophylaxis in cases of premature rupture of membranes. When intrauterine infection is suspected, the dose can be increased to 500 mg or more, and transplacental administration may be added to achieve a higher concentration in fetal blood. The present study simulates well premature rupture of membranes, and an amnioinfusion of antibiotics will be reliable and effective in managing premature rupture of membranes.

Infection and labor: the detection of endotoxin in amniotic fluid

Intra-amniotic infections are frequently caused by gram-negative organisms. Lipopolysaccharide, or endotoxin, is a component of the cell wall of these bacteria. The Limulus amebocyte lysate assay is the most sensitive test clinically available for the detection of endotoxin in biologic samples. The diagnostic value of the Limulus amebocyte lysate assay test for the detection of intra-amniotic infection has been examined and compared with that of the Gram stain. The Gram stain had a 60.8% sensitivity and 9.6% false positive rate. The Limulus amebocyte lysate assay had a 69% sensitivity and a 4.8% false positive rate. When both tests were used in combination, the sensitivity improved to 95.6%, whereas the false positive rate was 14.3%. The Limulus amebocyte lysate assay test is a rapid, sensitive, inexpensive, and simple test for the detection of gram-negative intra-amniotic infections.

C-reactive protein: a limited test for managing patients with preterm labor or preterm rupture of membranes?

C-reactive protein has been used to identify patients at high risk for infectious morbidity with preterm labor or preterm rupture of membranes. In this article we report on 104 patients with preterm labor symptoms (n = 45) or preterm rupture of the membranes (n = 59) and serial evaluations of C-reactive protein measured by latex agglutination and laser nephelometry. The simple, inexpensive latex method appears comparable to the laser method in predicting infectious morbidity and can be used clinically. Elevated C-reactive protein values before delivery predict infectious morbidity in only 8% to 29% of patients, and up to 18% of patients with serious infections may be misdiagnosed as having normal C-reactive protein values before delivery.

Pathogenesis and significance of urogenital mycoplasmal infections

U. urealyticum and M. hominis can no longer be considered as harmless commensals of the lower genitourinary tract. Both can produce disease in humans. Diagnosis and management of infections due to these organisms must be based upon isolation of the organisms from the affected site and preferably the number of organisms present. Due to the frequent resistance of both organisms to tetracycline, treatment must be based upon appropriate antibiotic sensitivities. For a more detailed description of the basic biology of these organisms and isolation and identification and treatment, the reader is referred to several recent reviews.

Phenotypic and cytotoxic characteristics of the immune cells of the human placenta

Despite some functional impairment of the newborn's T-cell immune system, most infants survive the intrauterine and perinatal period without succumbing to infection or maternal lymphocyte engraftment. The placenta may play a crucial role in protecting the infant from microbial and histocompatibility antigens. Accordingly, we studied phenotypic and functional capacities of placental cells. Placentas were obtained from uncomplicated pregnancies. Matched cord blood and maternal peripheral blood were also obtained in many instances. Fresh minced placental tissue was washed and digested with collagenase and DNase and mononuclear cells were obtained by density gradient centrifugation. The average yield was 10(6) cells/g of tissue with greater than 80% viability. Chromosome analysis of five placental preparations indicated that these cells were of fetal rather than maternal origin. The isolated placental cells consisted of trophoblasts, lymphocytes (74 +/- 3%), monocytes (16 +/- 3%), and granulocytes (8 +/- 2%). E-rosette forming cells (T cells) made up 65 +/- 2% and surface membrane immunoglobulin positive cells made up 8 +/- 1% of the placental mononuclear cells. Fluorescent activated analysis of the mononuclear cells indicated less Leu 4-positive cells (Pan-T) 43 +/- 3%, and less Leu 3-positive (T-helper cells) (25 +/- 2%), than cord and maternal cell preparations. Leu-2, DR, and B1 positive cells were similar to those in cord and maternal blood. Leu 7 and especially Leu 11 positive cells, markers for natural killer cells, were abundant in placental cells, making up 4 +/- 0.7% and 20 +/- 3%, respectively. The Leu 7/Leu 11 ratio of the placental cells was different from either the maternal or cord blood cells. Natural killer activity of placental cells against a K562 natural killer target was low, despite the abundance of cells with NK markers. The K562 activity was low in the placental cells, similar to the low NK activity of maternal and cord cells. Molt 4f killer activity was near normal. Lectin-dependent cytotoxicity using an EL-4 cell target plus PHA was low in placentas, compared to normal, maternal, or cord cell cytotoxicity. Matched samples indicated that LDCC activity was mother greater than cord greater than placenta. Antibody-dependent cytotoxicity (Raji target) of placental cells showed low activity, and again the paired studies indicated that normal controls greater than maternal greater than cord greater than placenta cytotoxicity.(ABSTRACT TRUNCATED AT 400 WORDS)