Group B streptococcal infection laboratory tests

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Rim Halaby, M.D. [2]

Overview

Any newborn with signs of sepsis should receive a full diagnostic evaluation and receive antibiotic therapy pending the results of the evaluation, regardless of the maternal Group B Streptococcus (GBS) colonization status. Well-appearing newborns whose mothers had suspected chorioamnionitis should undergo a limited diagnostic evaluation and receive antibiotic therapy pending culture results. No routine diagnostic testing for GBS is recommended among well-looking infants unless either the gestational age is <37 weeks or the duration of membrane rupture before delivery was ≥18 hours.^[1] The diagnosis of GBS infection is confirmed by the isolation of the organism in either the blood or the cerebrospinal fluid (CSF).

Laboratory Tests

Shown below is a table that summarizes the laboratory tests that are recommended in different scenarios of suspected early-onset GBS infection in neonates.^[1]

Scenario	Recommended Diagnostic Evaluation
Infants with signs of sepsis	Complete diagnostic evaluation (class A, level of evidence II) CBC including white blood cell differential and platelet count Blood culture Chest radiograph Lumbar puncture Culture of the cerebrospinal fluid (CSF)
Infants born to women with chorioamnionitis	Limited diagnostic evaluation (class A, level of evidence II) CBC including white blood cell differential and platelet count Blood culture
Well-appearing infants PLUS The mother had no chorioamnionitis and no indication for GBS prophylaxis	No routine diagnostic testing
Well-appearing infants PLUS The mother received adequate intrapartum GBS prophylaxis	No routine diagnostic testing (class B, level of evidence III)
Well-appearing infants PLUS The mother had an indication for GBS prophylaxis but received no or inadequate prophylaxis PLUS The infant is well-appearing PLUS Gestational age ≥37 weeks PLUS The duration of membrane rupture before delivery was <18 hours	No routine diagnostic testing (class B, level of evidence III)
Well-appearing infants PLUS Either gestational age <37 weeks OR The duration of membrane rupture before delivery was ≥18 hours	Limited diagnostic evaluation (class B, level of evidence III) CBC including white blood cell differential and platelet count Blood culture

In addition to the previous tests, the evaluation of suspected late-onset GBS sepsis requires the analysis of urine specimen collected by either catheterization or suprapubic aspiration.

Laboratory Findings

The diagnosis of GBS infection is confirmed by the isolation of the organism in either the blood or CSF. Blood cultures can be sterile in as many as 15% to 33% of newborns with meningitis.^[1]

Other laboratory findings that are indicative of an infection but non-specific to GBS include elevated WBC and abnormal findings in the CSF analysis. Thrombocytopenia might occur in the case of sepsis.

References

↑ ^1.0 ^1.1 ^1.2 Verani J.R., McGee L, and Schrag S.J. Prevention of Perinatal Group B Streptococcal Disease. Revised Guidelines from CDC, 2010.CDC.gov

Template:Bacterial diseases

Template:WikiDoc Sources

[CDCMMWR-1] 1.0 ^1.1 ^1.2 Verani J.R., McGee L, and Schrag S.J. Prevention of Perinatal Group B Streptococcal Disease. Revised Guidelines from CDC, 2010.CDC.gov

[1]

Group B streptococcal infection laboratory tests

Overview

Laboratory Tests

Laboratory Findings

References

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