Technical Data #2781a / 2013.06.15
Tood Hewitt Broth with gentamycin, nalidixic acid and blood is a liquid selective medium used to recover Streptococcus group B from vaginal tract. A rapid identification using this selective broth and a slide test with group B antiserum may be done and give positive results, without broth incubation, if the organism concentration is fairly high. Addition of blood shows hemolytic activity of Streptococcus group B.
in grams per liter purified filtered water
|Beef Heart, Infusion||
pH 7,6 +/- 0,2 à 25º C
This approximate formula may be adjusted and/or enriched to obtain best results.
This medium is for laboratory use only.
Store prepared media at 2-8° C protected from direct light. Medium must not be used if there are signs of contamination or if the expiry date has passed. Store dehydrate powder in a dry place in tightly-sealed containers at 2-25° C. Do not use dehydrated media if expiry date has passed.
Suspend 30 grams in 1000 ml of purified water. Heat gently with frequent agitation and boil for one minute. Sterilize at 121° C for 15 minutes and cool to 45-50° C. Add 1x10 ml of Gentamycin Supplement (8699) and 1x10 ml of Nalidixic Acid Supplement(8631); add 50 ml of defibrinated sheep blood (4245). Mix carefully and dispense aseptically into sterile culture tubes.
Bring prepared medium at room temperature before inoculation.
Expected results after 24 hrs at 35ºC W 5% CO2
LIMITATIONS OF METHOD
A positive result without incubation confirm an organism concentration of 107 per ml. If test is negative after 24 hours incubation, confirm by subculture. This is only a part of the identification. Other tests may be required.
|Dehydrated media||500 g||QB-39-4815|
|Tubes 16x125 mm||10/pkg||2781|
|Gentamycin Supplement, 10 ml||10/pkg||8699|
|Nalidixic Acid Supplement, 10 ml||10/pkg||8631|
|Defibrinated Sheep Blood||50 ml||4245|
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