Further studies on genital mycoplasmas in intra-amniotic infection: blood cultures and serologic response

The Maternal Serological Response to Intrauterine Ureaplasma sp. Infection and Prediction of Risk of Pre-Term Birth

Pre-term birth (PTB) associated with intrauterine infection and inflammation (IUI) is the major cause of early PTB less than 32 weeks of gestation. Ureaplasma spp. are common commensals of the urogenital tract in pregnancy and are the most commonly identified microorganisms in amniotic fluid of pre-term pregnancies. While we have an understanding of the causal relationship between intra-amniotic infection, inflammation and PTB, we are still unable to explain why vaginal Ureaplasma sp. colonization is tolerated in some women but causes PTB in others. It is now known that placental tissues are frequently colonized by bacteria even in apparently healthy pregnancies delivered at term; usually this occurs in the absence of a significant local inflammatory response. It appears, therefore, that the site, nature, and magnitude of the immune response to infiltrating microorganisms are key in determining pregnancy outcome. Some evidence exists that the maternal serological response to Ureaplasma sp. colonization may be predictive of adverse pregnancy outcome, although issues such as the importance of virulence factors (serovars) and the timing, magnitude, and functional consequences of the immune response await clarification. This mini-review discusses the evidence linking the maternal immune response to risk of PTB and the potential applications of maternal serological analysis for predicting obstetric outcome.

Genital mycoplasmas in placental infections

Objective: The involvement of the genital mycoplasmas Ureaplasma urealyticum and Mycoplasma hominis in complications of pregnancy has remained controversial especially because these microorganisms are frequent colonizers of the lower genital tract. Recovery of bacteria from the placenta appears to be the sole technique to represent a true infection and not vaginal contamination. Therefore, we investigated the presence of genital mycoplasmas, aerobic and anaerobic bacteria, and fungi in human placentas and evaluated their association with morbidity and mortality of pregnancy.

Methods: We cultured placentas from 82 women with complicated pregnancies. One hundred placentas from women with uncomplicated pregnancies were evaluated as controls. When possible, placentas were examined histologically for presence of chorioamnionitis.

Results: Microorganisms were recovered from 52% of the placentas of complicated pregnancies and U. urealyticum was the microorganism isolated most frequently from the placenta. A significant association between positive mycoplasma culture of the placenta and complication of pregnancy was found, and chorioamnionitis was positively related to isolation of mycoplasmas.

Conclusions: These data suggest that genital mycoplasmas are able to infect the human placenta where they can cause chorioamnionitis. This infection of the placenta by genital mycoplasmas is related to preterm birth and fatal outcome of pregnancy.

Proteomic biomarkers that predict the clinical success of rescue cerclage

OBJECTIVE

The origin of incompetent cervix is multifactorial, and the success of rescue cerclage is unpredictable. We tested amniotic fluid from women who were preparing to undergo rescue cerclage for proteomic biomarkers and correlated their presence with clinical outcome.

STUDY DESIGN

Amniocentesis was performed to facilitate rescue cerclage in 37 consecutive women with painless dilation (> 2 cm) and no detectable uterine activity for 4 hours (range, 1-24 hours) before cerclage. Thirty-nine consecutive women with a sonographically normal pregnancy and cervix who underwent amniocentesis for chromosomal testing during the same study interval at the same clinical site provided the control samples. A proteomic fingerprint was generated with the discarded sample and the Mass-Restricted score (MR score) for inflammation calculated. Peaks corresponding to free hemoglobin chains were sought as evidence of decidual hemorrhage or intra-amniotic bleeding.

RESULTS

Amniocentesis was performed at 23.5 weeks in cerclage (mean dilation, 4 cm) versus 19.5 weeks in control subjects. Cerclage subjects were delivered at 28.8 weeks; control subjects were delivered at 39.2 weeks. Thirty-two of 37 of cerclage subjects (86%) were delivered prematurely. Ten of 37 of cerclage subjects (27%), but no control subject, had a MR score that was indicative of inflammation (P < .001). Hemoglobin peaks were present in 12 of 37 of cerclage subject (32%), but no control subjects. Among cerclage subjects, those with a MR score of 3 to 4 were delivered earlier than those with a MR score of 0 to 2 (P < .001). Women with a MR score of 3 to 4 had a shorter latency period (days from amniocentesis to delivery; 3 days) and a shorter percentage of prolongation (1.8%) than women with a MR score of 0 to 2 (35 days; P < .05; 17.9%; P < .05). Women with hemoglobin had a shorter latency period (6 days) and a shorter percentage of prolongation (3.8%) than women without hemoglobin (38 days; P < .05; 21.8%; P < .05). Hemoglobin was present in 7 of 10 of the cerclage subjects (70%) with a MR score of 3 to 4. Women with both a MR score of 3 to 4 and hemoglobin had the shortest intervals to delivery.

CONCLUSION

These findings illustrate 2 pathologic mechanisms that are associated with preterm delivery are also associated with incompetent cervix. Either an intrauterine inflammatory response or decidual hemorrhage predates surgery in one half the women whose condition requires rescue cerclage. The activation of either mechanism predicts cerclage failure.

Proteomic biomarker analysis of amniotic fluid for identification of intra-amniotic inflammation

BACKGROUND

Intra-amniotic inflammation is associated with poor neonatal outcome independent of prematurity. We applied proteomic technology (SELDI: surface-enhanced laser desorption ionisation) to identify the proteomic profile of intra-amniotic inflammation.

DESIGN

One hundred and four samples of amniotic fluid were analysed. In stage 1, samples from patients with symptoms of preterm labour and known outcomes were tested to identify the characteristic profile for inflammation. We extracted the profile using a novel, stepwise logical approach comparing SELDI tracings from patients who delivered preterm and had intra-amniotic inflammation in response to infection to the tracings of patients who had symptoms of preterm labour but delivered at term. In stage 2, we applied the algorithm to samples from pregnancies whose outcomes were unknown to the investigators.

SETTING

North-American university in collaboration with Ciphergen field demonstration laboratory.

SAMPLE

One hundred and four samples of human amniotic fluid from transabdominal amniocentesis.

METHODS

SELDI (surface-enhanced laser desorption ionisation) and Mass Restricted analysis, a novel algorithm for extraction of clinical and biological relevant biomarkers from proteomic SELDI tracings.

MAIN OUTCOME MEASURE

Presence of intra-amniotic inflammation and/or infection leading to preterm birth.

RESULTS

Patients with intra-amniotic inflammation that deliver preterm have a distinctive amniotic fluid proteomic profile of three or four of the following proteins: neutrophil defensins-1 and -2, and calgranulins A and C. Based on the presence or absence of these biomarkers, we devised the mass restricted (MR) score ranging from 0 (all biomarker peaks absent) to 4 (all biomarker peaks present). In stage 1, MR score > 2 had 92.9% sensitivity (95% CI 76.5-98.9) and 91.8% specificity (95% CI 80.4-97.7) for detection of intra-amniotic inflammation. In blind testing (stage 2), MR score > 2 provided 100% specificity and sensitivity (95% CI 100-100). A MR score > 2 was associated with imminent preterm delivery.

CONCLUSION

Proteomic analysis of amniotic fluid reveals the presence of biomarkers characteristic of intrauterine inflammation. This methodology may identify the subgroup of patients that might benefit most from interventions to prevent fetal damage in utero.

Chorioamnionitis and endometritis

Chorioamnionitis complicates 1% to 2% of all pregnancies and may affect 10% of women with certain risk factors. Intraamnionic infection may result in devastating morbidity for both the fetus and the mother. Also, chorioamnionitis is associated with higher cesarean section rates. As demonstrated earlier, endometritis is a common complication of cesarean delivery alone. Nevertheless, antibiotic prophylaxis has been shown to reduce postpartum morbidity. In the face of chorioamnionitis and a cesarean delivery, the risk of developing endometritis increases exponentially. However, if appropriate antibiotic therapy is instituted at the time of diagnosis, fetal and maternal outcomes improve dramatically. Similar to chorioamnionitis, endometritis is usually polymicrobial in nature. The preponderance of the organisms isolated are anaerobic. Established risk factors include operative delivery, prolonged ruptured fetal membranes, and prolonged labor. The diagnosis is based primarily on clinical examination with fever and the exclusion of other sources of extrapelvic infection. Once the diagnosis is established, appropriate empiric antibiotics are instituted. Antibiotic therapy should be continued until the patient is afebrile and asymptomatic for 24 to 36 hours. Over the past 20 years, the use of single-agent therapy in these serious infections has been shown to be safe as well as effective. Once successful therapy is completed, the patient is discharged home with no oral antibiotics.

Isolation of genital mycoplasmas from blood of febrile obstetrical-gynecologic patients and neonates

In a prospective study, 1156 blood specimens collected from hospitalized febrile obstetrical-gynecologic patients and neonates with suspected sepsis, were inoculated into a conventional biphasic culture medium, Castaneda S and cultures incubated aerobically. 15-24 h later the broth cultures were subcultured to specific media for detection of mycoplasmas. Genital mycoplasmas were isolated in 15 samples (taken from 8 women) and in 2 from 1 neonate. Mycoplasmas and members of the family Enterobacteriaceae were the most frequent significant bacteria isolated from adult specimens. Mycoplasma isolations were associated with either postpartum or postabortum febrile infections in women. Four of the neonates, whose mothers were infected, showed respiratory distress at birth; 1 of them had mycoplasmas in the blood. All febrile states in obstetrical or gynecological patients, and in neonates, should routinely lead to blood cultures for detection of mycoplasmas and ureaplasmas.

Progress in pathogenesis and management of clinical intraamniotic infection

In the past decade, gratifying progress has been achieved in our understanding of clinical intraamniotic infection. With a usual incidence of 1% to 4%, clinical intraamniotic infection mainly develops as an ascending process after prolonged rupture of the membranes and labor, but other cases may be hematogenous in origin whereas still others complicate intrauterine procedures. The most common organisms isolated in amniotic fluid of cases of intraamniotic infections are anaerobes, genital mycoplasmas, group B streptococci, and Escherichia coli. The latter two are found most commonly in maternal or neonatal bacteremia complicating intraamniotic infection. Although the diagnosis remains largely a clinical one, laboratory tests have been suggested to confirm the diagnosis in women with symptoms. These include amniotic fluid Gram stain, gas-liquid chromatography, and leukocyte esterase measurement. Maternal treatment consists of antibiotic therapy and delivery. Studies to date have used a penicillin plus an aminoglycoside, with some authors advocating the addition of clindamycin after cesarean delivery. Other broad-spectrum regimens may be equally effective. Complications of clinical intraamniotic infections include an increase in cesarean section rate and in maternal and neonatal bacteremia. Poor neonatal outcomes in intraamniotic infection are more likely in the following cases: (1) when E. coli or group B streptococci are present in the amniotic fluid; (2) when the infant has a low birth weight; (3) when maternal antibiotic therapy is delayed until after delivery.

A study of three blood culture media for isolating genital mycoplasmas from obstetrical and gynaecological patients

Mycoplasma species are often found colonising the female genital tract. Their ability to become invasive and pathogenic, however, is often ignored, since attempts may not be made to culture these organisms from the bloodstream. We have investigated the ability of three types of blood culture media to support the growth of genital mycoplasmas. The media studied included brain-heart infusion broth, brain-heart infusion broth supplemented with 30% V/V sucrose and fastidious anaerobe broth. Genital mycoplasmas were cultured from the latter medium only. Since this was the sole medium which was liquoid-free, the inhibitory effects of liquoid on Mycoplasma spp. is discussed. This study comprised an investigation of 75 patients in obstetric and gynaecological wards with postpartum or post-operative fever. Genital mycoplasmas were isolated from five (6.7%) patients, four with Ureaplasma urealyticum and one with M. hominis. The value of considering these organisms in the differential diagnosis of fever in 'at risk' patients and of including appropriate media for their isolation is emphasised.

Reservoir of four organisms associated with bacterial vaginosis suggests lack of sexual transmission

This study consisted of a search for the possible reservoir and mode of spread of the four bacterial vaginosis-associated organisms Mobiluncus mulieris, Mobiluncus curtisii, Mycoplasma hominis, and Gardnerella vaginalis. Their occurrence in rectal, oral, and pharyngeal specimens from women with and without bacterial vaginosis, their male sexual consorts, four homosexual men, and children (altogether, 374 people) was studied. Genital samples were also obtained from all adults. All four organisms were isolated from the rectums of 45 to 62% of women with bacterial vaginosis and 10 to 14% of women without bacterial vaginosis. They also occurred in the rectums of males and children. M. hominis was recovered from the oropharynxes of 12 adults whose sexual consorts had genital occurrences of the organism. Mobiluncus spp. occurred only in the vaginas of women with bacterial vaginosis (97%). The organisms were only infrequently recovered from genital samples from 135 males. Organisms were recovered from the urethras and/or coronal sulci of 10 of 44 male consorts of women with bacterial vaginosis. However, after 2 weeks of condom use during sexual intercourse, only M. hominis remained in the urethra of one man. These findings suggest that the organisms associated with bacterial vaginosis are not spread sexually but colonize the vagina from an endogenous intestinal tract site. The pathophysiological mechanisms leading to bacterial vaginosis in a subpopulation of all women are still unknown.

Risk factors for intraamniotic infection: a prospective epidemiologic study

To determine the cumulative incidence of intraamniotic infection in our hospital and to identify potential risk factors for infection, 408 consecutive patients were followed up prospectively to determine development of intraamniotic infection. The clinical diagnosis of intraamniotic infection was made in 43 (10.5%) patients. Patients with intraamniotic infection were younger, of lower gravidity and parity, more likely to require oxytocin augmentation, and more likely to be monitored internally than were patients who were not infected. They also had longer durations of labor, ruptured membranes, and hospitalization before delivery, had significantly more vaginal examinations, and were more likely to be delivered of infants by cesarean section, as compared with patients without infection. Logistic regression analysis identified four variables independently associated with intraamniotic infection: the number of vaginal examinations, duration of ruptured membranes, use of internal monitors, and duration of total labor. Further study is necessary to clarify the role of these risk factors in the pathogenesis of intraamniotic infection so that infection control strategies can be developed.

Detection of Chlamydia trachomatis, Mycoplasma hominis and Ureaplasma urealyticum in pregnant Dutch women

A prospective study was performed to determine the prevalence of endocervical infection by Chlamydia trachomatis and vaginal colonization by Mycoplasma hominis and Ureaplasma urealyticum in pregnant women seeking routine obstetrical care in two clinics in the southern part of the Netherlands. C. trachomatis was detected using the direct immunofluorescence staining technique. For the genital mycoplasmata, generally accepted culture methods were used. Evaluable samples were obtained from 691 of 770 women in the first trimester of pregnancy. C. trachomatis was detected in 2.3%, M. hominis in 5.2% and U. urealyticum in 23.9% of the women. The isolation percentages of C. trachomatis and U. urealyticum were almost equally distributed in the different age groups. The prevalence of all three micro-organisms did not seem to be related to parity. Smoking and alcohol consumption seemed to influence the isolation rate of M. hominis and U. urealyticum.

Mycoplasma hominis in maternal and fetal infections

Although prevalence of M. hominis colonization during pregnancy varies from 12-50%, its role in infections of the mother and newborn infants is unclear. Definite correlations exist with chorioamnionitis and amniotic fluid infections, but as it is rarely isolated alone during these infections, its pathogenic role is uncertain. Its association with septic abortion is similarly questioned. Prevalence and antibody titers to M. hominis increase with increasing parity. Transient bacteremia occurs in approximately 2.5% of normal deliveries. M. hominis does have a significant role in postpartum fever. Women harboring the organism during labor with low predelivery antibody titers are at risk. Approximately 30% of exposed infants are colonized (4% of all infants) but there are only a few reports of neonatal meningitis, pneumonia, or skin abscesses due to M. hominis. Most recover without specific therapy. The role of antimicrobial therapy of M. hominis in pregnancy and the neonatal period is unclear. Further studies of these issues should simultaneously consider all potential genital tract pathogens.

Detection of antibodies to Ureaplasma urealyticum in pregnant women by enzyme-linked immunosorbent assay using membrane antigen and investigation of the significance of the antibodies

Optimal conditions of a microenzyme-linked immunosorbent assay using a group-specific membrane antigen of Ureaplasma urealyticum serotype 7 were established with rabbit antisera and applied for the evaluation of immunoglobulin M (IgM) and IgG antibodies in 139 serum specimens from pregnant women between 26 and 38 weeks of gestation, and the assay was compared with microorganism culture and investigated to determine the role of U. urealyticum in perinatal morbidity and mortality. U. urealyticum was isolated from 75 (54%) of 139 patients; 40 had a colonization greater than or equal to 10(6) cells per ml of swab (29%); 64 (85%) of 75 culture-positive patients had IgG antibodies (absorbance mean, 0.650), versus 4 (6%) of 64 culture-negative patients (absorbance mean, 0.103) (P less than 0.001). There was no cross-reactivity with Chlamydia trachomatis infection from patients from whom no mycoplasmas were isolated, but this cross-reactivity occurred in 24% of patients with other mycoplasma infections. There was a good correlation between quantitative evaluation of U. urealyticum colonization and antibody level (P less than 0.05). However, IgM antibody was found in 30% of culture-positive patients but also in 25% of the culture-negative group. Frequency of U. urealyticum colonization was greater in unmarried young women (less than 25 years old) with a history of genital infection, and a significantly greater frequency was detected in patients who smoked (P less than 0.01) and had a lower socioeconomic status (P less than 0.001). A lower infant birth weight was more associated with U. urealyticum colonization greater than or equal to 10(5) cells per ml. The enzyme-linked immunosorbent assay provided an additional means to diagnose and evaluate U. urealyticum infection in pregnant women.

Association of Ureaplasma urealyticum infection of the lower respiratory tract with chronic lung disease and death in very-low-birth-weight infants

Endotracheal aspirates from 200 infants who weighted less than or equal to 2500 g and who had evidence of respiratory disease were cultured within 24 h of birth for mycoplasmas, chlamydiae, viruses, and bacteria to evaluate the relation between lower respiratory tract infection and development of chronic lung disease and/or death. Ureaplasma urealyticum, an organism not visible on gram stain, not recovered on routine bacteriological media, and not susceptible to antibiotics commonly used to treat neonatal infections, was the single most common organism isolated. 14% of isolates were from infants born by caesarean section with intact membranes, which indicated that infection had occurred in utero. The findings probably represented true infection of the lower respiratory tract because the organism was recovered in pure culture in numbers greater than 10(3) from 85% of the infants, and also from the blood in 26% of infants. Those infants less than or equal to 1000 g with Ureaplasma urealyticum infection of the lower respiratory tract were twice more likely to have chronic lung disease or to die than were infants of similar birth-weight but who were uninfected, or infants greater than 1000 g. Very-low-birth-weight infants infected with ureaplasmas did not differ from those uninfected, either in demographic features or in potential risk factors for chronic lung disease.

Chronic Ureaplasma urealyticum and Mycoplasma hominis infections of central nervous system in preterm infants

In a prospective study of meningitis in 100 predominantly preterm infants, Ureaplasma urealyticum was isolated from the cerebrospinal fluid (CSF) of 8 and Mycoplasma hominis from the CSF of 5 babies undergoing investigation of suspected sepsis or treatment of hydrocephalus. U urealyticum was isolated from 6 infants with severe intraventricular haemorrhage and from 3 with hydrocephalus. In 4 babies multiple isolations were made over several weeks. There were clinical features of congenital infection with major neurological impairment in 1 infant infected with M hominis. Diagnosis is difficult because these organisms cannot be seen on gram stain and cannot readily be cultivated on routine bacteriological media, and CSF pleocytosis may be absent. This study, which used appropriate mycoplasmal media, shows that U urealyticum and M hominis are the most common microorganisms isolated from the CSF of newborn infants in a high-risk population.

Measurement of antibody to Mycoplasma hominis by an enzyme-linked immunoassay and detection of class-specific antibody responses in women with postpartum fever

The standard conditions for detection of human IgG, IgM, and IgA antibodies to Mycoplasma hominis by an enzyme-linked immunosorbent assay (ELISA) were established with the use of a cell lysate antigen and alkaline phosphatase conjugates. Antigen was used at a concentration of 10 micrograms of protein per milliliter, sera were diluted 1:200, and conjugates were diluted 1:500. Agreement between cultured isolation of M. hominis from the lower genital tract and presence of antibody in 207 women was 71%, 82%, and 86% for IgG, IgM, and IgA, respectively. When the ELISA was compared with the mycoplasmacidal assay, an overall agreement of 81% occurred, with the majority of the discrepancies occurring in the ELISA-positive and mycoplasmacidal-negative category. A linear relationship between end point titer and the A400 value (ELISA or absorbance value at 400 nm) at a standard serum dilution was demonstrated for the IgG, IgM, and IgA classes. Although the ELISA was relatively independent of antigen heterogeneity, no single strain detected more than 87% of positive sera, thus suggesting that optimum detection of antibody to M. hominis by the ELISA will require use of antigen pools derived from multiple strains of M. hominis.

Microbiology of the female genital tract

Patients who contract genital tract infections are predominantly young, are otherwise healthy, and generally respond well to treatment for bacterial infections. These infections are most commonly polymicrobial in etiology, with several noteworthy exceptions. Often there is an inciting event such as childbirth, surgical intervention, pregnancy termination or intrauterine contraceptive device insertion. With treatment, prognosis for cure is excellent; however, sequelae such as recurrent infections, infertility, or ectopic pregnancy can be serious. Bacteria encountered in the female genital tract can be divided into aerobic and anaerobic organisms. Among the aerobic gram-positive organisms, several varieties of streptococci such as Group B streptococci and enterococci occur frequently. Staphylococcus aureus is an infrequent but important pathogen. Among the aerobic gram-negative organisms, the most common is Escherichia coli. Klebsiella sp. and Proteus sp. occur in about 5% of genital tract infections. Species that are more resistant to antibiotics, such as Pseudomonas aeruginosa and Enterobacter sp., occur in approximately 1% or 2% of these cases and are more likely to appear in patients who have previously received antibiotic therapy or who have been hospitalized for some time. Among the anaerobic organisms, the most common gram-positive isolates are Peptostreptococci and Peptococci. Clostridia sp. occurs less frequently. Among the anaerobic gram-negative organisms, the Bacteroides sp. most frequently encountered are Bacteroides bivius and Bacteroides disiens. Bacteroides fragilis is still a common problem but appears to be less predominant. Other organisms encountered are Chlamydia trachomatis, the genital mycoplasmas, yeasts, protozoa, and viruses.