Chocolate Agar Medium

Cultivate and isolate fastidious organisms especially Neisseria spp., Haemophilus, and Gardnerella vaginalis using Thermo Scentific™ Chocolate Agar.

Hemoglobin in the Chocolate Agar formulation provides the X factor, and GCHI Enrichment provides the V factor required for growth of fastidious organisms. The presence of starch ensures that toxic metabolites produced by Neisseria are absorbed, and phosphate buffers are included to prevent changes in pH due to amine production that would affect the survival of the organism.

Neisseria are capnophilic, gram-negative diplococci or rods that occur in pairs or short chains and inhabit the mucous membranes of humans and animals. Neisseria gonorrhoeae and Neisseria meningitidis are two important pathogens in this group. Gonorrhea is a sexually transmitted disease caused by N. gonorrhoeae and is one of the most frequently reported infectious diseases in the United States and worldwide. This organism is oxidase-positive, and growth is best obtained on Chocolate Agar or Thayer Martin Agar. The treatment and control of gonorrhea is complicated by increasing resistance to a variety of antimicrobial agents, including penicillin, tetracycline, and fluoroquinolones.

Haemophilus are small, pleomorphic, gram-negative coccobacilli. They are nonmotile, non-sporeforming, fastidious, facultative anaerobes. Almost all species require preformed growth factors present in the blood, particularly the X factor (hemin) and/or V factor (NAD) for growth.

Gardnerella vaginalis is found in the genitourinary tract of females and is an indicator organism for bacterial vaginosis (BV). BV is a risk factor for premature labor, chorioamnionitis, and postpartum endometritis. Women with postpartum fever and neonates with sepsis may be infected with Gardnerella vaginalis. In males, Gardnerella vaginalis has been associated with urinary tract infections, prostatitis, and urethritis. Gardnerella vaginalis is a gram-variable rod or coccobacillus. Beta hemolysis is observed on human or rabbit blood-containing media, but not on Sheep Blood Agar.

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