Cary-blair transport medium: composition, preparation and uses

Gaurab Karki — Wed, 19 Dec 2018 11:46:32 +0000

Cary-blair transport medium

Cary-blairsemisolid transport medium is used to preserve the viability of entericpathogens in faeal specimens
Salmonella, Shigella, Vibrioand Yersinia enterocolittica survivewell in cary-blair medium for at least 48 hours (several days for Salmonella, Shigella, Vibrio species)and Campylobacter species for up to 6hours.
Carry- blair medium can be obtained in dehydratedform but it can be more economically prepared in the laboratory as follos

Dissolve the dry ingredients in the water by heating in a container of boiling water ( do not boil the medium)
Allow the medium to cool to 50°C and then add 4.5 ml of the freshly prepared calcium chloride solution and mix well.
Adjust the pH to 8.4 using 0.1 mol/I (N/10) sodium hydroxide.
Dispense the medium in 7ml amounts in screw-cap bottles of 9 ml capacity (large size Bijou bottles)
Sterilize by steaming (with caps loosened) for 15 minutes. When cool, tighten the bottle caps. Label the bottles.
Date the medium and give it a batch number. Record the expiry date (6 month from the preparation date) on each bottle.

It is also a good transport medium for Yersinia pestis.
Used to transport enteric bacteria (Salmonella, Shigella, Vibrio, Yersinia) from faecal specimen. *Immerse a swab of the faecal specimen in the medium, cutting off the swab stick to allow the bottle top be replaced tightly. Protect the swab from direct light and excessive heat.