College Lab Class Ends With 32 Students on Antibiotics After Deadly Pathogen Exposure

In a microbiology laboratory at the University of Midvale, a routine exercise designed to teach students how to identify common bacterial strains turned into a surprising educational moment. The instructor had prepared a sample of *Staphylococcus epidermidis*, a harmless skin commensal, and asked the students to determine its identity using standard staining and culture techniques. Instead of reporting the expected benign organism, every student concluded that the sample was *Bacillus anthracis*, the causative agent of anthrax.

The misidentification was traced to a combination of factors. The sample was grown on a selective agar that favored spore‑forming bacteria, and the students performed a Gram‑stain that produced a characteristic purple appearance. When the instructor asked for a confirmatory test, the students cited a misread of the colony morphology and the presence of a faint capsule on the Gram‑stain image. The incident prompted an immediate review of the lab’s safety protocols and a reminder that confirmatory tests, such as PCR or toxin assays, are essential before drawing conclusions about potential pathogens.

While the exercise did not pose a real health risk, it highlighted the importance of rigorous verification in microbiological diagnostics. The university has since updated its teaching materials to include a step for cross‑checking results with multiple assays and has scheduled a refresher workshop for faculty on best practices in pathogen identification. The incident serves as a reminder that even routine laboratory work can reveal gaps in training and protocol that, if unaddressed, could lead to serious mistakes in clinical or research settings.