Enhanced haemolysis Group B Strep Media


Hardy Diagnostics GBS Detect™ is recommended for the isolation and detection of gamma-hemolytic (non-haemolytic) Group B Streptococcus by inducing beta-haemolysis on sheep blood agar upon subculture from enrichment broth procedures; such as Strep B Carrot Broth™ and LIM Broth.


The Centers for Disease Control and Prevention (CDC) recommends the screening of all pregnant women for vaginal and rectal GBS colonization between 35 and 37 weeks of gestation using an enrichment broth followed by subculture to a Blood Agar plate (Cat. no. HDA10) or other appropriate media. The use of a selective enrichment broth that incorporates chromogenic pigments, such as Strep B Carrot Broth™, has recently been included in CDC's Recommendations for the Prevention of Group B Streptococcal Disease. Strep B Carrot Broth™ demonstrates increased sensitivity and specificity, reduced incubation time, reduced need for additional plated media, and elimination of the need to confirm positives with additional testing.

A small percentage of GBS may not produce beta-haemolysis. GBS detection with the Strep B Carrot Broth™ Kit is only possible with beta-haemolytic colonies. There is evidence of a direct genetic linkage between pigment production in Strep B Carrot Broth™ and haemolysin production by GBS bacteria. Beta-haemolytic, pigment producing GBS occurs with 95.3 to 99.5% of all GBS strains isolated from clinical specimens.

Subcultures of enrichment broths may contain non-haemolytic or gamma strains of GBS that may be missed by normal plating procedures, because non-haemolytic GBS is not readily distinguishable from other small non-haemolytic colonies. Therefore all LIM Broth cultures and negative Strep B Carrot Broth™ cultures should be subcultured to GBS Detect™ plates for detection of gamma-haemolytic GBS. GBS Detect plates contain special supplements that cause otherwise non-haemolytic strains of GBS to appear as beta-haemolytic, thus increasing the sensitivity of detection methods used to detect GBS colonization in pregnant women. Selective agents are added to suppress coliforms, staphylococci and other organisms that might be present as normal flora.

GBS Detect™ eliminates needless steps in screening for non-haemolytic group B streptococci and makes Strep B Carrot Broth™ a more sensitive method for all strains of GBS.


Storage: Upon receipt store at 2-8 degrees C. away from direct light. Media should not be used if there are any signs of deterioration (shrinking, cracking, or discoloration), haemolysis, contamination, or if the expiration date has passed. Product is light and temperature sensitive; protect from light, excessive heat, moisture, and freezing.

The expiration date applies to the product in its intact packaging when stored as directed.

This product has shelf life of 70 days from point of manufacture.


Method of Use: Medium should be brought to room temperature prior to inoculation. Inoculate according to standard microbiological procedures.

1. Using a vaginal-rectal specimen, inoculate Strep B Carrot Broth™ (Cat. no. HDZ140) according to the procedures in the technical information sheets.

2. Subculture all colour negative Strep B Carrot Broth™ to a GBS Detect™ plate. Streak inoculum in four quadrants to obtain isolated colonies. Note: Isolated colonies must be obtained.

3. Incubate the GBS Detect™ plate for 18-24 hours at 35 +/- 2 degrees C. in an aerobic atmosphere.

4. After 18-24 hours observe for growth of beta-haemolytic gram-positive, catalase-negative colonies. GBS will produce large, transparent zones of haemolysis, with a soft edge. Ignore small, incomplete or weak zones of haemolysis (most likely E. faecalis).

5. Using isolated colonies from the GBS Detect™ plate described in step 4, perform latex particle agglutination test (StrepPRO™ Grouping Kit, Cat. no. HDPL030HD) or other tests recommended for the detection of group B streptococci antigen following the procedure specified by the manufacturer.


It is recommended that biochemical and/or serological tests be performed on colonies from pure culture for complete identification.

Organisms other than GBS can produce faint or incomplete zones of hemolysis.


Standard microbiological supplies and equipment such as loops, swabs, applicator sticks, Strep B Carrot Broth™ (Cat. no. HDZ140), StrepPRO™ Grouping Kit (Cat. no. HDPL030HD), other culture media, incinerators, and incubators, etc., as well as serological and biochemical reagents, are not provided.


Cat: HDA300

Size: 10 Plates


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