Performance of eight commercial immunoassays for the detection of cytomegalovirus-specific IgM antibodies in pregnancy - no test fits all needs.

Detection of cytomegalovirus (CMV)-specific immunoglobulin M (IgM) antibodies as first-line serologic diagnosis plays an important role in identifying CMV primary infection during pregnancy. The performance characteristics of eight commercially available CMV IgM assays were compared. Sensitivity and IgM antibody kinetics were assessed using 100 acute phase and follow-up sera from 39 pregnant women with a well-defined onset of CMV primary infection. Specificity was analyzed using 50 well-characterized serum samples from pregnant women not infected or latently infected with CMV and from patients with other acute infections. Until 12 weeks after the onset of primary infection, four assays showed sensitivities of 100%, whereas the others had individual gaps to detect all primary infections in this time period. All assays showed a time-dependent decrease of IgM levels. More than 12 weeks after the onset of infection, the IgM-positive rates varied considerably between tests. The specificity was between 92% and 98% in all but one assay. The observed differences in the performance characteristics must be taken into account in CMV screening and diagnosis of primary infection during pregnancy.

Low-level positive results in the Liaison CMV IgG II assay may misclassify pregnant woman as immune.

The aim of this study is to report on the specificity in the low-positive range of the Liaison CMV IgG II assay for determination of cytomegalovirus immune status in pregnancy. Sera with test results between 12.0 and 40.0 U/mL were retested with the Enzygnost Anti-CMV/IgG assay. Enzygnost-negative samples were analyzed by the Serion ELISA classic Cytomegalovirus IgG assay and, if positive or equivocal, also with the Mikrogen recomLine CMV IgG assay. A total of 12,117 sera were tested with the Liaison assay. Sixty sera were equivocal (12.0-13.9 U/mL), and 400 of 4295 positive sera were low-positive (14.0-40.0 U/mL). Based on consensus, at least 14% of the low-positives and 1.3% of all Liaison-positives can be considered as misclassified. The proportion of misclassified sera increased with lower Liaison IgG results. We suggest that the range for equivocal results in the Liaison assay should be revised.

Primary cytomegalovirus (CMV) infection in pregnancy: Diagnostic value of CMV PCR in saliva compared to urine at birth.

BACKGROUND: Due to its ease of collection saliva was recently recommended as the preferred specimen, not only for screening, but also for diagnosis of congenital cytomegalovirus (CMV) infection. OBJECTIVE: To compare the diagnostic performance of saliva PCR to urine PCR in infants born to mothers with primary CMV infection during pregnancy. STUDY DESIGN: We retrospectively analyzed available data of infants tested for CMV DNA in urine and saliva at birth. PCR was performed with RealStar® CMV-PCR Kit 1.0 (altona Diagnostics). Infectious virus was detected in urine by rapid culture. RESULTS: A total of 133 newborns were eligible for final analysis. Saliva swabs and urine were collected at birth with a time interval of 0-8 days (median 0; IQR 0-1). In 55% of newborns, cord blood was also tested. The overall concordance of saliva and urine PCR was 91% (27 positive, 94 negative). In 12 cases with discordant findings the discrepancy was due to false-negative (n = 2) or false-positive (n = 10) PCR results in saliva. Compared to urine, PCR in saliva showed a positive predictive value of 73%. Viral load in saliva was significantly lower (p < 0.0001; Mann-Whitney test) in the 10 false-positive cases than in the 27 cases with concordantly positive results. CONCLUSIONS: Positive CMV PCR results in saliva, especially low positive, have to be confirmed by urine testing. In our opinion detection of CMV by PCR in neonatal urine remains the gold standard for diagnosing congenital CMV infection in infants of mothers with primary infection in pregnancy.

The value of CMV IgG avidity and immunoblot for timing the onset of primary CMV infection in pregnancy.

BACKGROUND: Primary CMV infections in pregnancy are usually asymptomatic and only detected by serology. Estimating the onset of infection is a major diagnostic goal, since primary infections around conception and in early gestation hold a higher risk for congenital disease than those in later pregnancy. OBJECTIVES: To assess the ability of serological supplementary CMV assays to date the onset of primary infection. STUDY DESIGN: From our routine diagnosis we identified 61 pregnant women (n=188 serum samples) with precisely determined onset of CMV primary infection either by IgG seroconversion (n=24) or by significant IgG antibody rise (n=37). One hundred and forty-seven sera were investigated using the VIDAS(®) CMV IgG avidity EIA (BioMèrieux) and 83 sera using the recomBlot CMV IgG with avidity (Mikrogen). RESULTS: Both assays proofed to be reliable in terms of timing the onset of CMV primary infection. An avidity index (AI) in the VIDAS avidity EIA of <40% indicated primary infection within the last 20 weeks (positive predictive value 93.4%; 99/106), whereas an intermediate AI excluded primary infection within the last 12 weeks (negative predictive value 88.2%; 15/17). The recomBlot showed high reliability (PPV 96.9%; 31/33) for timing the onset of infection within the last 14 weeks. Avidity testing by blot however could not be interpreted in 11 of 47 sera (23.4%). CONCLUSION: For timing the onset of infection (before or in early pregnancy) CMV avidity testing is most helpful if carried out within the first trimester up to the beginning of second trimester.

Cytomegalovirus (CMV) seroprevalence in pregnant women, bone marrow donors and adolescents in Germany, 1996-2010.

In Germany, studies on the IgG seroprevalence in pregnancy and in women of childbearing age are rare. Therefore, we retrospectively evaluated the CMV IgG seropositive rate in 40,324 pregnant women as well as in 31,093 female and male bone marrow donors over 15 consecutive years (1996-2010). Furthermore, the result of a study conducted in 1999 investigating 1,305 healthy adolescents with known ethnicity was included. The overall CMV IgG seroprevalence in pregnant women (15-50 years) was 42.3%. Age-dependent analysis revealed a significantly higher seropositive rate (55.6%) in young women (15-25 years) than in those aged 26-40 years (37-42%) and in women older than 40 years (48.3%). Over the study period of 15 years, the rate of seroprevalence in pregnant women declined significantly (χ(2) test < 0.01) from 44.3% in the first interval period (1996-2000), to 42.8% (2001-2005) and to 40.9% (2006-2010). The most influencing factor on CMV seropositivity appeared to be the socioeconomic status (SES), which we characterized by type of health insurance: Seroprevalence in women with low, middle and upper SES was 91.8, 46.9 and 33.7%, respectively. Female bone marrow donors of childbearing age (15-45 years) showed a significantly higher seropositive rate of 36.5% than age-matched male donors (28.6%). In adolescents aged 13-16 years, no gender-specific differences were recognized. Concerning ethnicity, youngsters with German descent had a significantly lower seroprevalence (29.9%) than those with non-German descent (67.4%).

Intrauterine transmission and clinical outcome of 248 pregnancies with primary cytomegalovirus infection in relation to gestational age.

BACKGROUND: The risk of intrauterine cytomegalovirus (CMV) infection and disease in the fetus or newborn largely depends on time of primary maternal infection during pregnancy. OBJECTIVES: Prospective cohort study of pregnancy outcome in relation to gestational age at primary maternal CMV infection. STUDY DESIGN: In a total of 248 pregnancies with primary infection the onset of infection was determined by IgG seroconversion, IgG avidity and/or onset of clinical symptoms. Congenital infection was diagnosed by CMV detection in amniotic fluid, fetal tissue or urine of the neonate in the first 2 weeks of life. Clinical symptoms were retrieved from ultrasound and medical records. RESULTS: The intrauterine transmission rates following primary CMV infection in the pre- and periconceptional period were 16.7% (4/24) and 34.5% (10/29), respectively. For the first, second and third trimester of pregnancy transmission rates were 30.1% (25/83), 38.2% (29/76) and 72.2% (26/36), respectively. The rate of symptomatically infected fetuses or newborns at birth was 22.8% for any symptoms and 10.3% for severe manifestations. No symptoms were observed in infected newborns of mothers with primary infection in the preconceptional period and in the third trimester. CONCLUSIONS: The risk of intrauterine transmission following primary maternal infection in the third trimester is high, but the risk of neonatal disease is low. The highest risk of severe symptoms in the fetus and newborn exists around conception and in the first trimester of pregnancy.