252: Acid-Fast Bacilli (AFB): An Introduction

It's time to revisit acid-fast bacilli (AFB)! What is acid-fastness? What stains are used to detect AFB, and how are AFB cultures processed? In this episode of Let's Talk Micro, Luis revisits a conversation with Dr. Filipe Muniz (Cerqueira) about the fundamentals of AFB. They discuss acid-fast staining, specimen processing, culture media, and the Runyon groups. Dr. Muniz also discusses nontuberculous mycobacteria (NTM), including examples of clinically relevant organisms and their characteristics. Whether you're new to clinical microbiology or looking for a refresher, tune in to this episode from the archives! Note: This episode was originally released on January 30TH  2025. At the time of recording, Dr. Muniz was serving as a clinical microbiology laboratory director at the University of Alabama at Birmingham (UAB). He is no longer in that role and is currently a medical student at UAB.   Stay connected with Let's Talk Micro: Website: letstalkmicro.com Questions or feedback? Email me at [email protected] Interested in being a guest on Let's Talk Micro? Fill out the form here: https://forms.gle/V2fT3asjfyusmqyi8 Support the podcast: Venmo Buy me a Ko-fi  

In 2026, a multistate outbreak of cyclosporiasis led to a significant increase in testing across clinical and public health laboratories. How did laboratories recognize the increase in cases? What diagnostic approaches were used, and how did laboratory data contribute to the outbreak investigation? In this episode of Let's Talk Micro, Luis is joined by Dr. Anisha Misra from Cleveland Clinic, Dr. Marie-Claire Rowlinson from bioMérieux, and Dr. Duane Newton from the Michigan Department of Health and Human Services to discuss the laboratory response to the 2026 Cyclospora outbreak. The conversation explores diagnostic methods for Cyclospora cayetanensis, the challenges of managing increased testing volumes, and the use of diagnostic data to identify emerging trends. The guests also discuss the role of molecular testing and sequencing in public health investigations, the importance of collaboration between clinical laboratories, industry, and public health agencies, and lessons learned that may help laboratories prepare for future outbreaks. Join us for a discussion about the critical role of clinical microbiology laboratories in outbreak detection, investigation, and response. Guests Anisha Misra, PhD — Cleveland Clinic Marie-Claire Rowlinson, PhD — bioMérieux Duane Newton, PhD — Michigan Department of Health and Human Services Resources CDC – Cyclosporiasis: https://www.cdc.gov/cyclosporiasis/ CDC DPDx – Cyclosporiasis: https://www.cdc.gov/dpdx/cyclosporiasis/ FDA – Cyclospora: https://www.fda.gov/food/foodborne-pathogens/cyclospora Stay connected with Let's Talk Micro: Website: letstalkmicro.com Questions or feedback? Email me at [email protected] Interested in being a guest on Let's Talk Micro? Fill out the form here: https://forms.gle/V2fT3asjfyusmqyi8 Support the podcast: Venmo Buy me a Ko-fi  

Metallo-β-lactamases (MBLs) have become an increasingly important topic in clinical microbiology and infectious diseases. While these enzymes were once encountered relatively infrequently in the United States, their epidemiology is changing, with NDM-producing organisms becoming more common. What makes metallo-β-lactamases different from other carbapenemases? Why are infections caused by MBL-producing organisms particularly challenging to treat? And what new treatment options are becoming available? In this episode of Let's Talk Micro, Luis is joined by Dr. Ryan Shields and Dr. Emily Heil to discuss metallo-β-lactamases and their growing clinical significance. They explore the differences between serine β-lactamases and MBLs, review important enzymes such as NDM, VIM, and IMP, and discuss the challenges associated with treating infections caused by MBL-producing organisms. The conversation also covers emerging treatment options, including aztreonam-avibactam and cefepime-zidebactam, and highlights the importance of identifying specific carbapenemases to guide antimicrobial therapy. Join us for a discussion on the evolving landscape of metallo-β-lactamases and the essential role of the clinical microbiology laboratory in patient care. Guests: Ryan Shields, PharmD — University of Pittsburgh Emily Heil, PharmD — University of Maryland School of Pharmacy and University of Maryland Medical Center Additional Reading: McCreary EK, Heil EL, Aitken SL, et al. The global epidemiology and treatment of metallo-β-lactamase-producing gram-negative pathogens. JAC-Antimicrobial Resistance. 2026;8(5). https://pubmed.ncbi.nlm.nih.gov/42876900/ Stay connected with Let's Talk Micro: Website: letstalkmicro.com Questions or feedback? Email me at [email protected] Interested in being a guest on Let's Talk Micro? Fill out the form here: https://forms.gle/V2fT3asjfyusmqyi8 Support the podcast: Venmo Buy me a Ko-fi  

When you open CLSI M100, what are you usually looking for? Susceptibility breakpoints? But did you know there's much more information available beyond susceptible, intermediate, and resistant interpretations? In this episode of Micro Minutes, we explore useful information found throughout CLSI M100, including its tables, comments, and appendices. From intrinsic resistance and predicting susceptibility to other antimicrobials to understanding why certain agents should not be reported as susceptible, we highlight practical examples that can help clinical microbiology professionals interpret antimicrobial susceptibility results. Whether you're a student or an experienced laboratory professional, join us as we take a closer look at CLSI M100 and discover what's beyond S, I, and R.   Stay connected with Let's Talk Micro: Website: letstalkmicro.com Questions or feedback? Email me at [email protected] Interested in being a guest on Let's Talk Micro? Fill out the form here: https://forms.gle/V2fT3asjfyusmqyi8 Support the podcast: Venmo Buy me a Ko-fi  

Have you ever performed an organism identification using MALDI-TOF mass spectrometry and received a result showing multiple possible species, such as Enterobacter cloacae and Enterobacter asburiae, or Citrobacter freundii and Citrobacter werkmanii? Why does this happen? What do these organisms have in common, and why are they classified into groups or complexes? In this episode of Micro Minutes, Luis explores bacterial groups and species complexes, why they exist, and how they relate to organism identification. He discusses several familiar and lesser-known examples, including the Enterobacter cloacae complex, Acinetobacter calcoaceticus–baumannii complex, Klebsiella pneumoniae species complex, Citrobacter freundii complex, and Pseudomonas putida group. The episode also highlights the Burkholderia cepacia complex and why species-level identification can be particularly important in patients with cystic fibrosis. Finally, learn why reporting an organism at the group or complex level is often appropriate, when additional identification may be necessary, and why understanding the capabilities and limitations of your identification system matters. Stay connected with Let's Talk Micro: Website: letstalkmicro.com Questions or feedback? Email me at [email protected] Interested in being a guest on Let's Talk Micro? Fill out the form here: https://forms.gle/V2fT3asjfyusmqyi8 Support the podcast: Venmo Buy me a Ko-fi  

As artificial intelligence (AI) becomes increasingly integrated into biological research, the quality of the data used to develop these technologies is more important than ever. But what exactly is digital biology, and why does data quality matter? In this episode of Let's Talk Micro, Luis is joined by Jonathan Jacobs, PhD, Senior Director of Bioinformatics at ATCC, to explore digital biology and the challenges associated with biological and genomic data. Dr. Jacobs discusses the importance of metadata, common issues with publicly available genomic databases, and why connecting digital information to authenticated biological materials is essential for reproducibility and reliable research. The conversation also explores how data quality can affect AI models, the role of existing standards, and what researchers can do to improve the accuracy, completeness, and usefulness of the data they generate and share. And, as always, stay until the end to hear Dr. Jacobs' favorite microorganism and what makes it so fascinating to him!   Resources Learn more about ATCC: https://www.atcc.org/ Stay connected with Let's Talk Micro: Website: letstalkmicro.com Questions or feedback? Email me at [email protected] Interested in being a guest on Let's Talk Micro? Fill out the form here: https://forms.gle/V2fT3asjfyusmqyi8 Support the podcast: Venmo Buy me a Ko-fi  

Many microbiology professionals are familiar with ATCC strains used for quality control, validation, and verification—but what happens before those biological materials reach the laboratory? ATCC, the American Type Culture Collection, maintains biological materials used by scientists and laboratories around the world. In this episode of Let's Talk Micro, Luis is joined by Dr. Shahin Ali, Senior Scientist at ATCC, to take a closer look at the work behind biological reference materials. Dr. Ali discusses how ATCC identifies and acquires microorganisms, what characteristics are considered when adding them to the collection, and how materials are authenticated, characterized, preserved, and maintained over time. The conversation also explores expert curation and complete provenance, why authenticated reference materials are important for laboratory quality and reproducibility, and how individual strains of the same species can have meaningful differences. Luis and Dr. Ali also discuss antimicrobial resistance, the growing importance of genomic and metadata quality, and how curated biological collections may support AI-driven research in the future. And, as always, stay until the end to hear Dr. Ali's favorite microorganism—and the personal connection behind his answer. Resources Learn more about ATCC: https://www.atcc.org/ Stay connected with Let's Talk Micro: Website: letstalkmicro.com Questions or feedback? Email me at [email protected] Interested in being a guest on Let's Talk Micro? Fill out the form here: https://forms.gle/V2fT3asjfyusmqyi8 Support the podcast: Venmo Buy me a Ko-fi  

Originally published on September 28, 2022, this episode returns to the Let's Talk Micro feed in recognition of World Rabies Day. Dr. Rodney Rohde joins the podcast to discuss rabies and his extensive experience working with the virus in public health. We start with the basics: What is rabies? How is it transmitted? What are the signs and symptoms? From there, we discuss potential exposures, post-exposure prophylaxis, vaccination, and ways to prevent rabies. Dr. Rohde also shares his experience working in rabies diagnostics and molecular epidemiology, as well as his involvement with wildlife rabies vaccination efforts. We also discuss the importance of recognizing potential exposures, the role of wildlife—particularly bats—and considerations when traveling to areas where rabies may be more prevalent. Finally, what is World Rabies Day, and why is it observed on September 28? Dr. Rohde discusses the history and significance of the day and the importance of education, prevention, and collaboration in the fight against rabies. Tune in as we revisit this conversation and learn more about rabies. Resources World Rabies Day: https://rabiesalliance.org/world-rabies-day Dr. Rohde's rabies book: https://www.elsevier.com/books/rabies/wilson/978-0-323-63979-8 Dr. Rohde's website: https://rodneyerohde.wp.txstate.edu/ Related publication: https://pubmed.ncbi.nlm.nih.gov/33659941/ Stay connected with Let's Talk Micro: Website: letstalkmicro.com Questions or feedback? Email me at [email protected] Interested in being a guest on Let's Talk Micro? Fill out the form here: https://forms.gle/V2fT3asjfyusmqyi8 Support the podcast: Venmo Buy me a Ko-fi  

MAD-ID (Making a Difference in Infectious Diseases) and the Society of Infectious Diseases Pharmacists (SIDP) have joined forces to create a new annual meeting focused on antimicrobial therapeutics, stewardship, infectious diseases, and more. In this episode of Let's Talk Micro, Luis is joined by Dr. Erin McCreary and Dr. Mike Rybak to discuss the history of MAD-ID and SIDP, what brought the two organizations together, and highlights from their 2026 meeting. They also discuss sessions relevant to clinical microbiology, practical approaches to applying new science, opportunities for networking and trainees, and what attendees can expect as the meeting moves forward under its new name: Antimicrobials Conference. Resources MAD-ID: https://www.mad-id.org/ Society of Infectious Diseases Pharmacists (SIDP): https://sidp.org/ Information on upcoming Antimicrobials Conference meetings: https://sidp.org/annualmeetings Want to check out the Breakpoints podcast?  https://breakpoints-sidp.org/ Stay connected with Let's Talk Micro: Website: letstalkmicro.com Questions or feedback? Email me at [email protected] Interested in being a guest on Let's Talk Micro? Fill out the form here: https://forms.gle/V2fT3asjfyusmqyi8 Support the podcast: Venmo Buy me a Ko-fi  

Group A Streptococcus (GAS) is a common cause of pharyngitis, but deciding who should be tested and which testing method to use isn't always straightforward. In 2025, the Infectious Diseases Society of America (IDSA) released updated guidelines on Group A streptococcal pharyngitis, bringing renewed attention to diagnostic stewardship and the use of clinical scoring systems to help guide testing decisions. In this episode of Let's Talk Micro, Dr. Christopher Doern returns to the podcast to break down the updated IDSA guidelines and what they may mean for clinical practice. We discuss clinical scoring systems such as Centor and McIsaac, antigen testing, culture, molecular diagnostics, and point-of-care testing. We also explore turnaround time and cost considerations, GAS carriage and the interpretation of positive results, and how diagnostic decisions connect with antimicrobial stewardship. Tune in as we take a practical look at what's changing in Group A strep testing and how laboratories and clinicians can approach these updated recommendations. This podcast episode is sponsored by Cepheid. The views and opinions expressed by the interviewer in this interview are their own and do not necessarily reflect the position of Cepheid. Resources IDSA Clinical Practice Guideline Update on Group A Streptococcal (GAS) Pharyngitis: IDSA 2025 Group A Streptococcal Pharyngitis Guideline Current Laboratory and Point-of-Care Pharyngitis Diagnostic Testing and Knowledge Gaps: https://pubmed.ncbi.nlm.nih.gov/39688598/ Stay connected with Let's Talk Micro: Website: letstalkmicro.com Questions or feedback? Email me at [email protected] Interested in being a guest on Let's Talk Micro? Fill out the form here: https://forms.gle/V2fT3asjfyusmqyi8 Support the podcast: Venmo Buy me a Ko-fi