Capsule Stain — Hiss Method
Description
The Capsule Stain Virtual Lab guides students through the Hiss capsule staining method using real photographs of laboratory tools at a realistic virtual bench. Students prepare an air-dried, non-heat-fixed smear from an old culture of Klebsiella pneumoniae. They stain it with crystal violet, rinse it with 20% copper sulfate instead of water, and blot it dry. Under oil immersion, they observe deep purple cells surrounded by light-blue capsular halos, and compare capsulated with non-capsulated bacteria. A troubleshooting section and a comprehensive final quiz complete the lab.
Learning Outcomes
By the end of this lab, students will be able to prepare a smear without heat fixation and perform the Hiss capsule stain correctly. They will explain the roles of crystal violet and copper sulfate, and why heat fixation and water rinsing are avoided. Students will distinguish deep purple cells from light-blue capsules under oil immersion and differentiate capsulated from non-capsulated organisms. They will also relate the bacterial capsule to virulence, phagocytosis resistance, and vaccine development.