Which medium is not appropriate for the cultivation of Neisseria gonorrhoeae?

• A. Chocolate agar
• B. Cefsulodin-irgasan-novobiocin agar
• C. Martin-Lewis agar
• D. Modified Thayer-Martin agar

Answer: (B)

Neisseria gonorrhoeae is a fastidious organism that requires enriched environments and selective conditions to grow in the presence of other microbes. Media choices for isolating gonorrhea are designed to provide essential growth factors while suppressing competing flora, so the organism can be recovered reliably.

Chocolate agar is enriched and furnishes the nutrients fastidious organisms need, including gonococcus, without strong suppression of contaminants. Martin-Lewis agar is a selective medium formulated to favor Neisseria species by inhibiting many competitors. Modified Thayer-Martin agar is a highly used selective medium containing antibiotics that suppress Gram-positives, many Gram-negatives, and fungi, enriching for Neisseria species like N. gonorrhoeae. Together, these media support or selectively favor gonococci.

Cefsulodin-irgasan-novobiocin agar, on the other hand, is designed to isolate Yersinia enterocolitica by using antibiotic components that strongly inhibit a broad range of bacteria, including Neisseria gonorrhoeae. Because those antibiotics would hinder the growth of gonococcus, this medium is not appropriate for cultivating N. gonorrhoeae.

So the medium not suitable for Neisseria gonorrhoeae is the one formulated to recover Yersinia, due to its antibiotic inhibitors that suppress gonococci.