Thermo Scientific™ HBT Bilayer Medium

Description

• Selectively isolate and presumptively identify Gardnerella vaginalis using Thermo Scientific™ Remel™ HBT Bilayer Medium (Human Blood-Polysorbate 80)
• Media used by earlier investigators to recover G
• vaginalis from clinical specimens include chocolate agar, peptone starch dextrose (PSD) agar, and Columbia colistin nalidixic acid agar 1-3
• Greenwood and Pickett developed V agar and demonstrated that G
• vaginalis is a beta-hemolytic on agar containing human blood but not on sheep blood agar 4,5
• Gardnerella vaginalis is a gram-variable rod or coccobacillus
• It is a venereally transmitted bacterium that causes bacterial vaginosis 6
• This is a condition characterized by an increase in the numbers of G
• vaginalis and various obligate anaerobes, and a concomitant decrease in lactobacilli observed on gram-stained smears
• HBT Bilayer Medium, formulated by Totten et al., consists of a bottom layer of Columbia colistin nalidixic acid agar supplemented with peptone, amphotericin B, and polysorbate 80 together with a top layer of the same media with 5% human blood added 7
• It shows significantly higher isolation rates of G
• vaginalis than those obtained with other media
• Use HBT BiLayer Medium for selective and presumptive identification of Gardnerella vaginalis
• Ready to use – Convenience of prepared media Selective medium - Colistin, nalidixic acid, and amphotericin B are selective agents that inhibit most gram-negative rods, yeast, and diphtheroids Easy to interpret - G
• vaginalis produces small, opaque colonies surrounded by a diffuse zone of beta-hemolysis The casein and meat peptones supply nutrients
• Phosphate buffer maintains pH and cornstarch neutralizes toxic fatty acids
• Polysorbate 80 enhances the diffusion of beta-hemolysis
• The top layer contains the same medium with addition of 5% human blood
• Since the zones of beta-hemolysis are viewed through a shallow layer of blood-containing medium, hemolysis is more distinct and easier to detect than with a single layer medium.