UT Southwestern researchers discover better tests to detect congenital syphilis in newborns

June 05, 2002

DALLAS - June 6, 2002 - A UT Southwestern Medical Center at Dallas research team has developed two blood tests that quickly and reliably diagnose congenital syphilis in newborns.

"This is the first study to document the presence of the syphilis spirochete (bacteria) in the cerebrospinal fluid of infected infants. Thus we are the first to accurately assess diagnostic evaluations of infants for the possibility of central nervous system invasion," said Dr. Pablo Sanchez, professor of pediatrics and senior author of the study appearing in today's issue of The New England Journal of Medicine.

Sanchez said the two blood tests detect either neonatal antibodies to the syphilis bacterium or the DNA of the syphilis organism itself as predictors of central-nervous-system (CNS) infection. Results from the two tests correlated with the detection of the organism in the infants' cerebrospinal fluid, and, therefore, the tests could serve as predictors of CNS infection.

This work produced the first valid data to select an effective, cost-efficient neonatal treatment regimen for congenital syphilis.

A pregnant woman with syphilis has about a 60 percent to 80 percent chance of infecting her fetus. Infants born to mothers with syphilis are traditionally hospitalized for multiple daily injections of penicillin over a 10-day period because physical exams and conventional laboratory tests are unable to detect all cases. The most accurate lab test until now required a three-month incubation period.

The UT Southwestern study showed that two tests - immunoglobin M (IgM) immunoblotting and polymerase chain reaction (PCR) - detected all cases of central-nervous- system infection in the group of 148 infants studied. The babies were born to syphilis-infected mothers during the 1989-1999 study period.

Earlier research at UT Southwestern had suggested that congenital syphilis might stimulate a detectable reaction by the newborn's immune system, despite its immature development, said Dr. Michael Norgard, chairman of microbiology and a co-author of the study.

"We believed we could evaluate this by searching for the presence in neonatal blood of the infant's IgM antibodies," Norgard said. The study confirmed the theory.

The researchers also successfully modified the PCR test - a technique commonly used by forensic scientists to reveal DNA or RNA molecular sequences - to detect the DNA of the syphilis organism in the blood.

"The diagnostic gap had been further aggravated by the belief and clinical experience indicating that up to 50 percent of infants with congenital syphilis are born without any telltale clinical signs or symptoms and otherwise appear to be healthy babies," Norgard said. "The detection of neonatal IgM antibodies seems to be the best single surrogate marker for substantiating infection of the infant."

The blotting test, similar to an AIDS diagnostic tool, is a molecular technique for detecting IgM antibodies in the serum of infected infants.

"I believe that this work, spanning more than a decade, will stand alone as the most thorough description of the diagnosis of a rare but potentially devastating infection in newborns," said Dr. George Wendel Jr., a professor of obstetrics and gynecology who worked on the study.

The study focused primarily on 76 of the 148 examined infants, most at 1 day of age but ranging up to 3 months old. Among the 76 infants, those whose mothers had not been treated with antibiotics while pregnant, 17 were found to have central nervous system invasion by Treponema pallidum, the bacterium that causes syphilis, Sanchez said. While traditional physical exams, spinal taps, arm- and leg-bone X-rays, and blood-cell counts identified up to 16 of the 17 babies with infected nervous systems, the IgM immunoblotting and PCR tests were required to detect all 17 cases, he reported.

Sanchez said the findings support newly revised syphilis treatment guidelines issued by the Centers for Disease Control and Prevention and the American Academy of Pediatrics.

"Previously, using a fail-safe approach, the CDC had recommended a blanket 10-day regimen of two to three daily penicillin doses for every baby born to a mother with syphilis," he said. "But often all that is needed is one dose for infants with no invasion of the central nervous system. Our study shows us the tools that help to identify both the infants who need the 10-day treatment and those who can be treated effectively with one dose of long-acting penicillin."

Other researchers on the study included lead author Dr. Ian Michelow, a pediatric infectious diseases research fellow, and Fiker Zeray, a senior registered nurse in pediatrics.

The study was supported by the CDC and the National Institute of Allergy and Infectious Diseases.
-end-
To automatically receive news releases from UT Southwestern via e-mail, send a message to UTSWNEWS-REQUEST@listserv.swmed.edu. Leave the subject line blank and in the text box, type SUB UTSWNEWS.

UT Southwestern Medical Center

Related DNA Articles from Brightsurf:

A new twist on DNA origami
A team* of scientists from ASU and Shanghai Jiao Tong University (SJTU) led by Hao Yan, ASU's Milton Glick Professor in the School of Molecular Sciences, and director of the ASU Biodesign Institute's Center for Molecular Design and Biomimetics, has just announced the creation of a new type of meta-DNA structures that will open up the fields of optoelectronics (including information storage and encryption) as well as synthetic biology.

Solving a DNA mystery
''A watched pot never boils,'' as the saying goes, but that was not the case for UC Santa Barbara researchers watching a ''pot'' of liquids formed from DNA.

Junk DNA might be really, really useful for biocomputing
When you don't understand how things work, it's not unusual to think of them as just plain old junk.

Designing DNA from scratch: Engineering the functions of micrometer-sized DNA droplets
Scientists at Tokyo Institute of Technology (Tokyo Tech) have constructed ''DNA droplets'' comprising designed DNA nanostructures.

Does DNA in the water tell us how many fish are there?
Researchers have developed a new non-invasive method to count individual fish by measuring the concentration of environmental DNA in the water, which could be applied for quantitative monitoring of aquatic ecosystems.

Zigzag DNA
How the cell organizes DNA into tightly packed chromosomes. Nature publication by Delft University of Technology and EMBL Heidelberg.

Scientists now know what DNA's chaperone looks like
Researchers have discovered the structure of the FACT protein -- a mysterious protein central to the functioning of DNA.

DNA is like everything else: it's not what you have, but how you use it
A new paradigm for reading out genetic information in DNA is described by Dr.

A new spin on DNA
For decades, researchers have chased ways to study biological machines.

From face to DNA: New method aims to improve match between DNA sample and face database
Predicting what someone's face looks like based on a DNA sample remains a hard nut to crack for science.

Read More: DNA News and DNA Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.