• "For the microbiologic diagnosis of gonorrhea, culture is necessary for anti-microbial susceptibility testing, due to the large numbers of resistant strains.
  • In males, the diagnosis is based upon Gram staining of a urethral exudate.
    • The presence of intracellular Gram-negative diplococci is diagnostic of gonorrhea.
  • In females, the normal flora of the vagina confounds direct diagnosis by Gram stain.
    • Culture is required.
  • Due to the fact that N. gonorrheae is rapidly killed by drying, the culture plate must be streaked in the examination room.
    • A Thayer-Martin (or equivalent) bi-plate is normally used.
  • The left side of the plate contains chocolate agar, whereas the right side of the plate contains chocolate agar plus antibiotics.
    • This inhibits normal flora and allows primarily the gonococcus to grow.
  • Occasional strains of gonococcus will be resistant to the antibiotics in the agar, so both sides must be streaked."
  • Some institutions have recombinant DNA test for the gonococcus that eliminates the need for Thayer-Martin plates, but you may still have to use this culture method in many hospitals or clinics.
  • Ó 1999 KUMC Pathology and the University of Kansas, used with permission; courtesy of Dr. James Fishback, Department of Pathology, University of Kansas Medical Center.