[Diagnosis of congenital and perinatal infection by cytomegalovirus using polymerase chain reaction]

Cytomegalovirus Shedding in Seropositive Pregnant Women From a High-Seroprevalence Population: The Brazilian Cytomegalovirus Hearing and Maternal Secondary Infection Study

Background

Most congenital cytomegalovirus (CMV) infections in highly seropositive populations occur in infants born to women with preexisting CMV seroimmunity. Although essential for developing prevention strategies, CMV shedding patterns in pregnant women with nonprimary infections have not been characterized. We investigated correlates of CMV shedding in a cohort of seropositive pregnant women.

Methods

In a prospective study, saliva, urine, vaginal swabs, and blood were collected from 120 CMV-seropositive women in the first, second, and third trimesters and 1 month postpartum. Specimens were tested for CMV DNA by polymerase chain reaction. We analyzed the contribution of the specific maternal characteristics to viral shedding.

Results

CMV shedding was detected at least once in 42 (35%) women. Mothers living with or providing daily care to young children (3-6 years) were twice as likely to shed CMV at least once compared to women with less exposure to young children (58% vs 26%; adjusted relative risk [aRR], 2.21; 95% confidence interval [CI], 1.37-3.56). Living in crowded households (≥2 people per room) was associated with viral shedding (64% vs 31%; aRR, 1.99; 95% CI, 1.26-3.13). Sexual activity as indicated by the number of sexual partners per year or condom use was not found to be a correlate of viral shedding.

Conclusions

CMV shedding is relatively frequent in seropositive pregnant women. The association between virus shedding and caring for young children as well as crowded living conditions may provide opportunities for increased exposures that could lead to CMV reinfections in seropositive women.

Cytomegalovirus frequency in neonatal intrahepatic cholestasis determined by serology, histology, immunohistochemistry and PCR

AIM: To determine cytomegalovirus (CMV) frequency in neonatal intrahepatic cholestasis by serology, histological revision (searching for cytomegalic cells), immunohistochemistry, and polymerase chain reaction (PCR), and to verify the relationships among these methods.

METHODS: The study comprised 101 non-consecutive infants submitted for hepatic biopsy between March 1982 and December 2005. Serological results were obtained from the patient’s files and the other methods were performed on paraffin-embedded liver samples from hepatic biopsies. The following statistical measures were calculated: frequency, sensibility, specific positive predictive value, negative predictive value, and accuracy.

RESULTS: The frequencies of positive results were as follows: serology, 7/64 (11%); histological revision, 0/84; immunohistochemistry, 1/44 (2%), and PCR, 6/77 (8%). Only one patient had positive immunohistochemical findings and a positive PCR. The following statistical measures were calculated between PCR and serology: sensitivity, 33.3%; specificity, 88.89%; positive predictive value, 28.57%; negative predictive value, 90.91%; and accuracy, 82.35%.

CONCLUSION: The frequency of positive CMV varied among the tests. Serology presented the highest positive frequency. When compared to PCR, the sensitivity and positive predictive value of serology were low.

Placental transfer of naturally acquired, maternal cytomegalovirus antibodies in term and preterm neonates

Maternal antibodies may protect the fetus and neonate against severe forms of CMV-caused disease, therefore this study investigated the efficiency of the placental transfer of naturally acquired, maternal total anti-cytomegalovirus (CMV) IgG and neutralizing antibodies at different gestational ages. The study was conducted on 182 healthy CMV-seropositive Brazilian mothers and their 196 infants who were not infected congenitally with CMV, as determined by CMV detection in urine. The study groups were composed of 44 infants aged 28-30 weeks; 51 infants aged 31-33 weeks; 62 infants aged 34-36 weeks, and 39 infants of gestational age > or = 37 weeks. Quantitative detection of total CMV IgG was carried out using EIA and virus neutralizing titers were determined by a microneutralization assay in sera from mothers and infants. CMV IgG levels and neutralizing titers of the infants correlated with maternal levels (r=0.873 and r=0.841, respectively). The efficiency of placental transfer of these antibodies was enhanced significantly as gestation progressed until 34-36 weeks, when values similar to those of full-term infants (90-100%) were found. Transfer ratios were significantly higher for neutralizing compared to total CMV IgG antibodies at gestational age 31-33 weeks (100% vs. 84%, respectively) and at gestational age 28-30 weeks (75% vs. 60%, respectively). We conclude that placental transfer of naturally acquired maternal CMV neutralizing and total CMV IgG antibodies are similarly efficient above 34 weeks of gestational age. At less than 34 weeks of gestational age, transfer of neutralizing antibodies may be favored and these antibodies reach the neonatal serum of 99% of these premature infants.

Usefulness of blood and urine samples collected on filter paper in detecting cytomegalovirus by the polymerase chain reaction technique

A rapid test for the diagnosis of congenital CMV infection is still needed. This study evaluated the usefulness of dried blood and urine samples collected on filter paper for detecting cytomegalovirus (CMV) by the polymerase chain reaction (PCR) assay compared with the use of liquid urine. Samples were obtained from 332 infants aged 1-7 days. Liquid urine samples were collected into bags, cultured in human fibroblasts, and processed using a multiplex PCR technique. Dried urine samples were obtained by placing a piece of filter paper in contact with the infant's genitals. The heels of neonates were punctured and capillary blood was blotted onto filter paper and dried. Dried blood and urine specimens were analyzed by multiplex PCR and nested-PCR assays. A diagnosis of congenital CMV infection was established by isolating the virus, and by detecting viral DNA in the liquid urine. Of the 332 liquid urine samples collected from 332 neonates, seven (2.1%) were positive for CMV and 325 were negative, by both cell culture and PCR assay. In dried samples, CMV DNA was detectable only with a nested PCR assay. Compared with known CMV infection status, 5/7 (71.4%) neonates were positive for congenital CMV infection using dried blood samples. All 325 uninfected neonates were negative. In the dried urine samples, 4/4 CMV-infected infants gave positive tests, and all 262 uninfected infants were negative. Although further improvements in sample collection and/or processing are still needed, PCR testing on dried urine or blood collected on filter paper is a promising approach in the diagnosis of neonatal CMV infection.

Congenital cytomegalovirus infection in preterm and full-term newborn infants from a population with a high seroprevalence rate

BACKGROUND

Cytomegalovirus (CMV) is the most frequent cause of congenital infections in humans. Prematurity occurs in as many as 34% of infants with symptomatic congenital CMV infection.

OBJECTIVE

To determine the clinical presentation and frequency of congenital CMV infection among preterm infants and full-term infants from a population with a high seroprevalence rate.

DESIGN/METHODS

A total of 289 preterm infants (median gestational age, 34 weeks; median birth weight, 1,757 g) and 163 term infants (median gestational age, 39 weeks; median birth weight, 3,150 g) sequentially born were included in the study. Serum IgG antibodies to CMV were measured in all mothers. One urine sample was collected within the first 7 days of age from all newborns. Virus isolation in urine samples was performed by tissue culture, and viral DNA was detected by a multiplex PCR. CMV infection was diagnosed in infants with virus excretion detected by both methods on at least two occasions within the first 3 weeks of life.

RESULTS

Maternal CMV seropositivity rate was 95.7%. Congenital CMV infection was detected in 6 of 289 (2.1%) (95% confidence interval, 0.84 to 4.68) preterm infants and in 3 of 163 term infants (1.8%) (95% confidence interval, 0.48 to 5.74) (P > 0.05). Four of 6 preterm infants with congenital CMV infection were symptomatic, but none of the term infants was symptomatic (P = 0.16).

CONCLUSION

The frequency of congenital CMV infection in preterm newborn infants from mothers with a high seropositive rate was similar to that found in term infants. No significant difference was found between the proportion of symptomatic infants among preterm and term infants. Our finding of symptomatic congenital CMV infection underscores the need of further evaluation of correlates of congenital symptomatic infection in highly immune populations.