Shannon A. Ross

Saliva Polymerase-Chain-Reaction Assay for Cytomegalovirus Screening in Newborns

BACKGROUND Congenital cytomegalovirus (CMV) infection is an important cause of hearing loss, and most infants at risk for CMV-associated hearing loss are not identified early in life because of failure to test for the infection. The standard assay for newborn CMV screening is rapid culture performed on saliva specimens obtained at birth, but this assay cannot be automated. Two alternatives--real-time polymerase-chain-reaction (PCR)-based testing of a liquid-saliva or dried-saliva specimen obtained at birth--have been developed. METHODS In our prospective, multicenter screening study of newborns, we compared real-time PCR assays of liquid-saliva and dried-saliva specimens with rapid culture of saliva specimens obtained at birth. RESULTS A total of 177 of 34,989 infants (0.5%; 95% confidence interval [CI], 0.4 to 0.6) were positive for CMV, according to at least one of the three methods. Of 17,662 newborns screened with the use of the liquid-saliva PCR assay, 17,569 were negative for CMV, and the remaining 85 infants (0.5%; 95% CI, 0.4 to 0.6) had positive results on both culture and PCR assay. The sensitivity and specificity of the liquid-saliva PCR assay were 100% (95% CI, 95.8 to 100) and 99.9% (95% CI, 99.9 to 100), respectively, and the positive and negative predictive values were 91.4% (95% CI, 83.8 to 96.2) and 100% (95% CI, 99.9 to 100), respectively. Of 17,327 newborns screened by means of the dried-saliva PCR assay, 74 were positive for CMV, whereas 76 (0.4%; 95% CI, 0.3 to 0.5) were found to be CMV-positive on rapid culture. Sensitivity and specificity of the dried-saliva PCR assay were 97.4% (95% CI, 90.8 to 99.7) and 99.9% (95% CI, 99.9 to 100), respectively. The positive and negative predictive values were 90.2% (95% CI, 81.7 to 95.7) and 99.9% (95% CI, 99.9 to 100), respectively. CONCLUSIONS Real-time PCR assays of both liquid- and dried-saliva specimens showed high sensitivity and specificity for detecting CMV infection and should be considered potential screening tools for CMV in newborns. (Funded by the National Institute on Deafness and Other Communication Disorders.).

DRIED BLOOD SPOT REAL-TIME POLYMERASE CHAIN REACTION ASSAYS TO SCREEN NEWBORNS FOR CONGENITAL CYTOMEGALOVIRUS INFECTION

CONTEXT Reliable methods to screen newborns for congenital cytomegalovirus (CMV) infection are needed for identification of infants at increased risk of hearing loss. Since dried blood spots (DBS) are routinely collected for metabolic screening from all newborns in the United States, there has been interest in using DBS polymerase chain reaction (PCR)-based methods for newborn CMV screening. OBJECTIVE To determine the diagnostic accuracy of DBS real-time PCR assays for newborn CMV screening. DESIGN, SETTING, AND PARTICIPANTS Between March 2007 and May 2008, infants born at 7 US medical centers had saliva specimens tested by rapid culture for early antigen fluorescent foci. Results of saliva rapid culture were compared with a single-primer (March 2007-December 2007) and a 2-primer DBS real-time PCR (January 2008-May 2008). Infants whose specimens screened positive on rapid culture or PCR had congenital infection confirmed by the reference standard method with rapid culture testing on saliva or urine. MAIN OUTCOME MEASURES Sensitivity, specificity, and positive and negative likelihood ratios (LRs) of single-primer and 2-primer DBS real-time PCR assays for identifying infants with confirmed congenital CMV infection. RESULTS Congenital CMV infection was confirmed in 92 of 20,448 (0.45%; 95% confidence interval [CI], 0.36%-0.55%) infants. Ninety-one of 92 infants had positive results on saliva rapid culture. Of the 11,422 infants screened using the single-primer DBS PCR, 17 of 60 (28%) infants had positive results with this assay, whereas, among the 9026 infants screened using the 2-primer DBS PCR, 11 of 32 (34%) screened positive. The single-primer DBS PCR identified congenital CMV infection with a sensitivity of 28.3% (95% CI, 17.4%-41.4%), specificity of 99.9% (95% CI, 99.9%-100%), positive LR of 803.7 (95% CI, 278.7-2317.9), and negative LR of 0.7 (95% CI, 0.6-0.8). The positive and negative predictive values of the single-primer DBS PCR were 80.9% (95% CI, 58.1%-94.5%) and 99.6% (95% CI, 99.5%-99.7%), respectively. The 2-primer DBS PCR assay identified infants with congenital CMV infection with a sensitivity of 34.4% (95% CI, 18.6%-53.2%), specificity of 99.9% (95% CI, 99.9%-100.0%), positive LR of 3088.9 (95% CI, 410.8-23 226.7), and negative LR of 0.7 (95% CI, 0.5-0.8). The positive and negative predictive values of the 2-primer DBS PCR were 91.7% (95% CI, 61.5%-99.8%) and 99.8% (95% CI, 99.6%-99.9%), respectively. CONCLUSION Among newborns, CMV testing with DBS real-time PCR compared with saliva rapid culture had low sensitivity, limiting its value as a screening test.

Cytomegalovirus Reinfections in Healthy Seroimmune Women

Cytomegalovirus (CMV) reinfections have been associated with damaging congenital infection and adverse outcomes in transplant recipients. To determine the frequency of and risk factors for CMV reinfections, 205 seropositive women were followed up prospectively. The appearance of new antibody specificity against 1 of 4 polymorphic epitopes was considered as evidence of CMV reinfection. Approximately one-third of the study participants (59 [29%] of 205) were noted to have CMV reinfection during follow-up. None of the exposure factors were associated with CMV reinfection. Women with antibodies against at least 1 of the 4 antigens at baseline had a 63% decreased risk of reinfection, suggesting a protective role for strain-specific immunity.

Congenital Cytomegalovirus Infection: Clinical Outcome

Congenital cytomegalovirus (CMV) infection is a leading cause of hearing loss and neurologic disabilities in children worldwide. Infants with symptomatic congenital CMV infection at birth are at significantly increased risk for developing adverse long-term outcomes. The vast majority of infants with congenital CMV infection have no clinical findings at birth (asymptomatic infants), and about 10%-15% of these children develop long-term sequelae. Currently, predictors of adverse outcome in asymptomatic congenital CMV infection are not known, and it is important that future studies address this issue.

Cytomegalovirus Strain Diversity in Seropositive Women

ABSTRACT Infection and reinfection with multiple cytomegalovirus (CMV) strains have been shown to occur in immunocompromised individuals, sexually transmitted disease clinic attendees, and children attending day care centers. To characterize the CMV diversity in healthy seropositive individuals, 16 CMV PCR-positive specimens from 113 seropositive women were analyzed for glycoprotein gN and gB genotypes by cloning, followed by nucleotide sequencing of the plasmid DNA and/or restriction fragment length polymorphism (RFLP). The results showed that most (93.7%) of the PCR-positive specimens contained multiple gN and/or gB genomic variants, suggesting that the majority of women were infected with more than one virus strain. The results also showed that the RFLP technique might not be sufficiently sensitive to detect all of the genomic variants present in a sample.

Cytomegalovirus blood viral load and hearing loss in young children with congenital infection.

Background: This study was designed to determine whether elevated viral load in infants and young children is associated with congenital cytomegalovirus (CMV)-related hearing loss. Methods: Blood samples were obtained from 135 children with congenital CMV infection. CMV DNA in the peripheral blood was quantitated with a real-time polymerase chain reaction assay. Viral load measurements were analyzed in 3 different age groups (<2 months, 2–12 months, 12–36 months). Results: In children with symptomatic and asymptomatic infection, CMV DNA levels were not different between children with hearing deficit and those with normal hearing in all 3 age groups. In children with asymptomatic infection, the positive predictive value of a peripheral blood viral load >3500 genomic equivalents per milliliter (ge/mL) at <2 months and 2 to 12 months of age is 8%, and at 12 to 36 months of age is 11.8%. However, the negative predictive value of a viral load <3500 ge/mL is 94.4% at <2 months of age, and 100% at 2 to 36 months of age. Conclusions: Peripheral blood viral load is not associated with hearing loss in children with congenital CMV infection. However, a viral load of <3500 ge/mL is associated with a lower risk of hearing loss in children born with asymptomatic congenital infection.

Mixed Infection and Strain Diversity in Congenital Cytomegalovirus Infection

BACKGROUND Cytomegalovirus (CMV), the most common cause of congenital infection, exhibits extensive genetic variability. We sought to determine whether multiple CMV strains can be transmitted to the fetus and to describe the distribution of genotypes in the saliva, urine, and blood. METHODS Study subjects consisted of a convenience sampling of 28 infants found to be CMV-positive on newborn screening as part of an ongoing study. Genotyping was performed on saliva specimens obtained during newborn screening and urine, saliva, and blood obtained at a later time point within the first 3 weeks of life. RESULTS Six (21.4%) of the 28 saliva samples obtained within the first 2 days of life contained >1 CMV genotype. Multiple CMV genotypes were found in 39% (5/13) of urine, saliva, and blood samples obtained within the first 3 weeks of life from 13 of the 28 newborns. There was no predominance of a CMV genotype at a specific site; however, 4 infants demonstrated distinct CMV strains in different compartments. CONCLUSIONS Infection with multiple CMV strains occurs in infants with congenital CMV infection. The impact of intrauterine infection with multiple virus strains on the pathogenesis and long-term outcome remains to be elucidated.

Overview of the diagnosis of cytomegalovirus infection.

Cytomegalovirus (CMV) is recognized as the most common congenital viral infection in humans and an important cause of morbidity and mortality in immunocompromised hosts. This recognition of the clinical importance of invasive CMV disease in the setting of immunodeficiency and in children with congenital CMV infection has led to the development of new diagnostic procedures for the rapid identification of CMV. Diagnosis of acute maternal CMV infection by the presence of immunoglobulin (Ig)M and low-avidity IgG requires confirmation of fetal infection, which is typically performed using polymerase chain reaction (PCR) assays for CMV on amniotic fluid. Viral culture of the urine and saliva obtained within the first two weeks of life continues to be the gold standard for diagnosis of congenitally-infected infants. PCR assays of dried blood spots from newborns have been shown to lack sufficient sensitivity for the identification of most neonates with congenital CMV infection for universal screening purposes. However, saliva PCR assays are currently being assessed as a useful screening method for congenital CMV infection. In the immunocompromised host, newer rapid diagnostic assays, such as phosphoprotein 65 antigenemia and CMV real-time PCR of blood or plasma have allowed for preemptive treatment, reducing morbidity and mortality. However, lack of standardized real-time PCR protocols hinders the comparison of data from different centers and the development of uniform guidelines for the management of invasive CMV infections in immunocompromised individuals.

Detection of Congenital Cytomegalovirus Infection by Real-Time Polymerase Chain Reaction Analysis of Saliva or Urine Specimens

Viral culture of urine or saliva has been the gold standard technique for the diagnosis of congenital cytomegalovirus (CMV) infection. Results of rapid culture and polymerase chain reaction (PCR) analysis of urine and saliva specimens from 80 children were compared to determine the clinical utility of a real-time PCR assay for diagnosis of congenital CMV infection. Results of urine PCR were positive in 98.8% of specimens. Three PCR-positive urine samples were culture negative. Results of saliva PCR and culture were concordant in 78 specimens (97.5%). Two PCR-positive saliva samples were culture negative. These findings demonstrate that PCR performs as well as rapid culture of urine or saliva specimens for diagnosing congenital CMV infection and saliva specimens are easier to collect. Because PCR also offers more rapid turnaround, is unlikely to be affected by storage and transport conditions, has lower cost, and may be adapted to high-throughput situations, it is well suited for targeted testing and large-scale screening for CMV.

Association between Genital Tract Cytomegalovirus Infection and Bacterial Vaginosis

Women with sexually transmitted diseases (STDs) and bacterial vaginosis (BV) have increased rates of cytomegalovirus (CMV) seroprevalence and CMV seroconversion. To characterize the association between genital tract CMV infection and BV, vaginal wash specimens from 52 women attending an STD clinic were analyzed. Significantly more women with BV shed CMV in the lower genital tract than did women without BV. In addition, most of the women who were shedding CMV were infected with >1 virus strain. These results suggest that local CMV replication and infection with multiple CMV strains is facilitated by the presence of BV.