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Gonorrhea

  • "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.

1999 KUMC Pathology and the University of Kansas, used with permission; courtesy of Dr. James Fishback, Department of Pathology, University of Kansas Medical Center.

 

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