228: Gram-Negative Cocci: What to Do After the Gram Stain

In this episode of Let's Talk Micro, we continue our gram-negative cocci series by focusing on what to do after the Gram stain. You've identified gram-negative cocci—now what?

We take a practical, bench-focused approach to working these organisms up, covering key culture media like blood agar, chocolate agar, and selective media such as Modified Thayer-Martin and Martin-Lewis. We also review collection and transport considerations, including JEMBEC and CO₂ requirements for Neisseria gonorrhoeae.

We then dive into commonly used tests, including ONPG for differentiating Neisseria lactamica and Neisseria meningitidis, the CTA test and its limitations, and the butyrate esterase test for identifying Moraxella catarrhalis.

This episode is all about building confidence at the bench—connecting what you see to what you do next.

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