New system for cultivation of Neisseria gonorrhoeae

A modified Thayer-Martin medium, containing 2.0% agar, 0.25% dextrose, and 5.0 mug of trimethoprim per ml was compared to Thayer-Martin medium for growth of stock cultures of Neisseria gonorrhoeae and for isolation of N. gonorrhoeae from clinical specimens. Stock cultures and male urethral cultures grew equally well on both media, but the modified Thayer-Martin medium detected 10% more female patients positive for gonococci. A description is given of the use of a citric acid-sodium bicarbonate tablet for generating carbon dioxide in a sealed plastic bag containing a culture plate. Equivalent results were obtained on duplicate plates of 336 cultures and specimens when this procedure was compared with the standard candle jar extinction method of incubation. The tablet and plastic bag system has the advantages of economy, ease of use, and safety.