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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In this episode of Let's Talk Micro, we kick off a new series on gram-negative cocci by starting where it all begins—the Gram stain.

Seeing gram-negative diplococci on a smear can feel intimidating, especially when you're on the bench and need to make the right call. In this episode, we focus on how to approach that moment with confidence. We walk through the key organisms you'll encounter, including Neisseria, Moraxella, and Veillonella, and discuss how morphology, specimen source, and clinical context all come together to guide your thinking. We also revisit a correction from a previous episode regarding carbohydrate utilization in Neisseria species.

This episode is all about building a strong foundation—how to think before jumping to identification.

Stay tuned for the next episode, where we'll dive into the media and tests used to identify these organisms in the lab.

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• Website: letstalkmicro.com

• Questions or feedback? Email me at letstalkmicro@outlook.com

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The CLSI M100 gets updated every year—but what do those changes actually mean for the microbiology lab?

In this episode of Let's Talk Micro, Luis is joined by Dr. April Bobenchik to break down the latest updates in the CLSI M100 2026 (36th edition) and how they translate into real-world lab practice.

They walk through important breakpoint changes, including aztreonam–avibactam and updates for Acinetobacter, along with new additions like trimethoprim-sulfamethoxazole breakpoints for beta-hemolytic streptococci. Another notable update this year is the updated anaerobic antibiogram and how it can be used to help guide decisions in the lab. The conversation also touches on antimicrobial tiers, why some breakpoints are temporarily removed, and practical ways labs can approach implementing new updates.

If you work in clinical microbiology, this episode will help you stay current and confident with the latest M100 changes.

Access CLSI M100 for free: https://em100.edaptivedocs.net/Login.aspx

Stay connected with Let's Talk Micro:

• Website: letstalkmicro.com

• Questions or feedback? Email me at letstalkmicro@outlook.com

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