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31-03-2013 | Gynaecology | Article

Group B strep detection improved for pregnant women

Abstract

Free abstract

medwireNews: Researchers have developed a rapid diagnostic test that can identify Group B Streptococcus (GBS) colonization in antepartum patients in just 6.5 hours, while simultaneously allowing for the determination of antimicrobial susceptibility.

"This new test could change the management of patients who present to labor and delivery with threatened preterm labor and aren't expected to deliver right away," said lead author Jonathan Faro, from The University of Texas Health Science Center in Houston, USA, in a press statement.

Currently, culture methods take 48 hours to identify GBS and a further 4 hours if testing of antibiotic sensitivity is necessary, explain Faro and team. "While culture continues to be regarded as the gold standard, it is labor intensive and is not without shortcomings."

The new test could "help cut down on overuse of resources and minimize our contribution to the increased level of bacterial resistance," they suggest.

For the study, the researchers processed three vaginal-rectal swabs taken from each of the 356 women evaluated, who were at 35 to 37 weeks' gestation. They processed two of the samples using traditional culture (commercial laboratory and in-house culture) and the third specimen was processed using an antibody-based accelerated test, in which a sample is placed over an antibody-coated membrane, cultured for 6 hours, and then any bound GBS detected by adding a secondary, labeled antibody.

As reported in Infectious Diseases in Obstetrics and Gynecology, the prevalence of GBS was 23.6% with commercial processing, 29.5% with in-house testing, and 36.8% with the accelerated GBS test.

When the in-house GBS culture was used as the reference standard, the accelerated GBS test demonstrated a sensitivity of 97.1% and a specificity of 88.4%.

"The accelerated GBS test demonstrated a high level of sensitivity and specificity for the detection of antepartum GBS within 6.5 hours," write Faro and team, who highlight the "unique potential" for simultaneous microbial resistance testing during the culture stage of the test.

"A clinician may be armed with both the identification of the agent causing infection and the appropriate antibiotic needed to provide optimal treatment," they say.

"This not only has the potential of saving time and resources, but will also allow for improved clinical outcomes and reduce the burden of microbial resistance which may develop from empirical prophylaxis," conclude the authors.

By Sally Robertson, medwireNews Reporter

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