Test Catalog

Test ID: CGBS    
Group B Streptococcus (Streptococcus agalactiae) Culture, Varies

Useful For Suggests clinical disorders or settings where the test may be helpful

Screening for maternal colonization with Streptococcus agalactiae at 36 to 37 weeks gestation as a guide for intrapartum antibiotic prophylaxis to decrease the risk of infection by S agalactiae (group B streptococcus) in the infant

Testing Algorithm Delineates situations when tests are added to the initial order. This includes reflex and additional tests.

When this test is ordered, the reflex tests may be performed and charged.

Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test

Streptococcus agalactiae (group B streptococcus) is a cause of morbidity and mortality among infants. Infections occurring within the first week of life are considered early-onset; those occurring in infants greater than 1 week of age are considered late-onset. Maternal vaginal or rectal colonization with S agalactiae is a risk factor for early-onset disease in infants. Ten to 30% of pregnant women are vaginally or rectally colonized with S agalactiae and may transmit the organism to their infant during labor and delivery. The American College of Obstetricians and Gynecologists recommends screening for colonization with S agalactiae at 36 to 37 weeks gestation as a guide for intrapartum antibiotic prophylaxis to decrease the risk of infection with Streptococcus agalactiae in the infant.

Reference Values Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.


Interpretation Provides information to assist in interpretation of the test results

Positive cultures are reported out as Streptococcus agalactiae.

Cautions Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances

No significant cautionary statements

Clinical Reference Recommendations for in-depth reading of a clinical nature

Prevention of Group B Streptococcal Early-Onset Disease in Newborns: American College of Obstetricians and Gynecologists Committee Opinion. July 2019;(134):1. https://www.acog.org/Clinical-Guidance-and-Publications/Committee-Opinions/Committee-on-Obstetric-Practice/Prevention-of-Group-B-Streptococcal-Early-Onset-Disease-in-Newborns