Clinical Microbiology


CHROMagar™ StrepB

Click on the picture for
Packaging / Colonies appearance

For isolation and differentiation of Streptococcus agalactiae (GBS)

Typical Appearance of microrganisms

Streptococcus B –› Mauve
Other Microorganism
→ blue, colourless or inhibited

Order References 

Please use these references when
contacting your local distributor:

5000 mL...........SB282
25 L.................SB283-25

To download the certificate of analysis, please indicate your lot number below :


Medium Performance

Compared to CNA Blood Agar and Granada:

  1. Easy interpretation: easier reading thanks to an intense and sensitive mauve colony colouration.

  2. High sensitivity: detection of GBS, including non-haemolytic strains, with sensitivity close to 100 %.

  3. High selectivity: differenciation of GBS from other bacteria by selective inhibition or by counter-colouration.

  4. Fast: results in 18-24 h.

  5. Simplicity: incubation in aerobic conditions. Confirmation by latex agglutination can be performed directly on the colony.

Medium Description

Gain flexibility using powder rather than ready to use plates: Use the entire pack, or just a portion if there is a need for a smaller number of plates,. If kept under appropriate storage temperature, CHROMagar StrepB has more than 18 months shelf life. This flexibility is essential to avoid the waste resulting from expired-unused plates. 

In the USA: For Research Use Only
Please refer to our notice and Material Safety Data Sheet for complete information about the medium.
CHROMagar™, Rambach™, AquaCHROM™ are trademarks created by Dr. A. Rambach.

Last Update: 09-Dec-19

Focus on Streptococcus agalactiae

GBS in pregnant women:
The Group B Streptococci (GBS), also known under the name of Streptococcus agalactiae, are the cause of numerous infections in adults but mostly an important cause of serious neonatal infections, occuring in the three first weeks of life. Studies indicate that approximately 12-27 % of pregnant women are colonised by GBS. (WHO, Infectious diseases, Group B Streptococcus).
Detecting vaginal (and in some countries also rectal) colonisation by GBS in pregnant women is the most effective strategy to prevent infection transmission during baby delivery.

Worldwide, official guidelines recommend prenatal screening of GBS in the last month of pregnancy. In GBS-carrying women, this screening allows determining the need of intrapartum antibiotic prophylaxy, which has been proved effective in preventing the infections occuring in the first week of life (known as early-onset GBS infections).

Invasive GBS disease:
In addition to the neotal infection issue, GBS infections have been frequently observed in immunodepressed people: adults with diabetes, breast cancer, cirrhosis or neurological impairement. This appears by soft tissue infection, bone infections, pneumonia or less frequently, meningitis. The elderly have a high rate of mortality when invaded by GBS. (WHO/ Clin Infect Dis. 2001 Aug 15;33(4):556-61. Epub 2001 Jul 20).
It is thus essential to detect invasive GBS desease to limit (I) the patient treatment period, the costs involved and (II) the emergence of resistance in Streptococci.


CHROMagar Strep B and Granada Media for detection of group B Streptococcus in vaginal/rectal prenatal screening


E. Grenzner, E. Dopico, M. Aguilar, S. Herrero, M.A. Sanchez, R. Manchado Laboratori Clinic l' Hospitalet, Institut Català de la Salut, L'Hospitalet de Llobregat (Barcelona), Spain

Comparison of culture-based methods for Group B Streptococcus detection in screening samples from pregnant women


B.Berg, M.Hatto, W.LeBar, D.Newton, C.Young University of Michigan Health System, Ann Arbor, MI

Evaluation of CHROMagar™ StrepB agar, an aerobic chromogenic medium for prepartum vaginal/rectal Group B Streptococcus screening


Didier-Marc Poisson, Marie-Liesse Evrard, Claire Freneaux, Marie-isabelle Vivès and Louis Mesnard Microbiology Laboratory & Gynaecology Obstetric Ward, Centre Hospitalier Régional Orléans, FR
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