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Neisseria is a large group of gram-negative proteobacteria. Neisseria meningitidis, the causative agent of meningitis, is responsible for a large amount of morbidity and mortality throughout the world while Neisseria gonorrhoeae is the causative agent of the sexually transmitted disease gonorrhea that is second in cases reported only to chlamydia (CDC). These fastidious organisms can be cultivated on Dextrose Starch Agar. The medium is highly nutritious and supports the luxuriant growth of various fastidious organisms like N. meningitidis, Streptococcus pyogenes and Streptococcus pneumoniae without the need of supplementation with additives. Organisms lacking the ability of starch hydrolysis can be maintained on this medium. However when used as a stock culture agar for maintenance, the medium should be taken in half concentrations. Organism capable of hydrolyzing starch will create acidic conditions thereby making it unsuitable for maintenance.

Dextrose Starch Agar was used to test the activity of various antibiotics against Neisseria species by the agar dilution technique as demonstrated by Wilkins, Lewis and Barbiers (4). N. meningitidis grow luxuriantly on this medium, when the plates are kept in 4-6%CO2 environment or in the presence of abundant moisture. Swancara (3) has described a method of obtaining partial carbon-dioxide tension and this can be used for incubation of Dextrose Starch Agar plates inoculated with N. meningitidis. Proteose peptone and gelatin serve as sources of nitrogen and carbon essential for microbial growth. Dextrose serves as the energy source. Starch neutralizes toxic fatty acids that may be present in the agar. Sodium chloride maintains the osmotic balance and buffering is achieved by inclusion of disodium phosphate.

Dextrose Starch Agar prepared in half strength is a good medium for maintaining stock cultures of gonococci. The medium normally contains a flocculent precipitate, which does not affect the nutritive value of the medium. It is necessary to have the incubation atmosphere saturated with moisture while cultivating gonococci. Suitable conditions can be achieved, if the plates are incubated in a closed container containing cotton or towel saturated with water. Best results are obtained on a solid medium with a moist surface.