CONTINUING EDUCATION :: WOMEN’S HEALTH Current clinical practices are focused on the identification of
women who are colonized with GBS and are, therefore, at highest risk of transmission to the newborn infant to target administra- tion of intrapartum antibiotic prophylaxis (IAP).10
GBS screening for pregnant women is recommended between the 36-38-week mark using a vaginal-rectal swab.8
twenty-four (18 to 24) hour broth enrichment of the swab is recommended prior to detection of GBS by either subsequent culture or PCR-based detection because enrichment has been shown to increase the sensitivity of detection.11-12
If the results
are positive, the patient can be treated with antibiotics during labor. This approach demonstrably reduces the risk of mother- to-baby transmission, reducing EOD occurrence.13 There are several FDA cleared NAATs available for antepartum or intrapartum detection of GBS organisms from vaginal-rectal swab specimens collected from pregnant women. However, the sensitivity of NAATs may be significantly decreased when used for rapid testing while a mother is in labor because the 18-24 hour enrichment step cannot be included in those situations. Neonatal cases of GBS disease have occurred in babies born to mothers whose screens were negative during pregnancy, which underscores the need for high sensitivity testing.5 In the event an infected mother passes GBS to her baby, time is
HSV1 and HSV2 both lead to lifelong infections, but many people never realize they have the virus. Without testing, pregnant women may be unaware of the risk to their babies.
In addition to providing an accurate diagnosis, the speed of molecular testing helps ensure that a newborn gets the best treatment. When a mother is known to have HSV — especially if she was first infected while pregnant, which may be the most dangerous situation for the developing baby — doctors often start the baby on antiviral and antibiotic treatments immediately. Getting reliable answers about the baby’s infection status in an hour means that at least one of those treatments can be de-escalated quickly.6
GBS testing Among newborns, infection by Group B Streptococcus is one of the leading causes of both meningitis and sepsis, making it a serious concern for neonatal care. According to an estimate from the U.S. Centers for Disease Control and Prevention, 25% of pregnant women are asymptomatically colonized with GBS in genital and rectal mucous membrane areas that a baby would be exposed to during vaginal birth.7 infected mothers get infected themselves.8
Half of the babies born to Vertical transmission
of GBS to the newborn occurs either shortly before or during delivery, and can result in an invasive infection known as early- onset disease (EOD). Infants with EOD will present with fever, lethargy, sepsis, pneumonia, and, more rarely, meningitis within the first 24 to 48 hours of life. In the 1970s, GBS emerged as the primary cause of infection of infants in the first week of life with fatality rates as high as 50%. In 1990, the CDC estimated an incidence of GBS disease of 1.8 cases per 1,000 live births, but as a result of universal screening and intrapartum antibiotic treatment, GBS EOD has been reduced to an incidence of 0.23 infants per 1,000 live births as of 2015.9
On average, even with
universal screening in place, 1,000 babies in the United States develop EOD each year, with approximately 4 to 6% leading to death. Late-onset disease (LOD) can also occur in the neonate around 3 to 4 weeks of age and typically manifests as bacteremia or meningitis with approximately 1,000 babies in the United States affected per year.7
10 MAY 2022
MLO-ONLINE.COM
of the essence. Severe infections in the infant can trigger dangerous symptoms within the first day or two after delivery. Rapid diagnosis of GBS infection in the newborn is essential for positive outcomes. Conventional testing for GBS is performed with culture using blood agar plates followed by a confirmation test such as Christie, Atkins, and Munch-Peterson (CAMP) factor reaction or latex agglutination, which can be labor-intensive and delay results up to 48 hours.9
While this time-consuming process may be
acceptable for testing the expectant mother at 36-38 weeks, it is not suitable for testing a newborn who may quickly spiral into a severe and time-sensitive infection crisis. The presence of GBS DNA in normally sterile body fluids such as CSF provides presumptive evidence of neonatal infection. More and more, physicians are turning to GBS molecular di-
agnostics instead of conventional culture both for newborns and mothers. These tests’ high sensitivity and specificity outperform that of culture.12
Multiplex panel PCR assays are available in
many clinical laboratories for direct testing of CSF that include GBS and other central nervous system pathogens. And given the severity of the risk to an infected neonate, obstetricians cannot afford to miss a positive case in a pregnant woman. Rapid results from a molecular test can also be a significant benefit if the patient goes into pre-term labor, allowing her healthcare team to manage risk carefully through the use of prophylactic antibiotics during labor. For pregnant women allergic to penicillin — the antepartum treatment typically prescribed to reduce GBS transmission — culture and subsequent susceptibility testing remain helpful for characterizing the pathogen’s antibiotic resistance profile and selecting the best course of treatment.
CMV testing Human cytomegalovirus (CMV) infection is common and usually results in a mild, non-specific illness in otherwise healthy indi- viduals followed by asymptomatic latency. It is estimated that 50% of adults are infected by age 40 in the U.S. alone.14
Universal Eighteen to
However,
congenital CMV can wreak havoc during fetal development, and perinatal CMV can cause severe symptoms in newborns. CMV causes more cases of congenital disease than the 29 most com- monly screened metabolic and endocrine disorders combined. About 90% of babies born with congenital CMV infection will
Photo coutesy of Luminex
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52
