Question

NEISSERIA EXPERIMENT MICROBIOLOGY LAB (Revised March 2016) Background There are two main pathogens in the genus Neisseria: N.gonorrhoeae and N meningitidis, along with many species which are normal flora for mucus membranes like the nasopharynx, vagina, urogenital tract, etc. In order to diagnose gonorrhea in a male, a Gram stain of the urethral discharge should reveal Gram negative diplococci and many white blood cells. This is considered sufficient grounds to treat for gonorrhea. In a female, diagnosis must be based on culture, since there is so much normal flora present in the vagina, and Gram negative diplococcic seen from a Gram stain of this area could represent many other organisms which are NOT causing disease. The media used to grow and isolate N. gonorrhoeae is very selective - it is a chocolate-based agar, but it has additives like Vancomycin to inhibit growth of the normal flora so that the growth of N. gonorrhoeae, if present, will be enhanced, and easier for lab personnel to isolate. Procedure: 1. Examine the Gram stain of pus from a Neisserial infection. If this were a urethral exudate from a male patient, what would be the most likely diagnosis? Is it necessary to plate out the remaining penile exudate? If this were vaginal mucous, a rectal culture, mouth culture or eye culture, what should be done to diagnose this infection?

Answer 1

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