MicrobeLibrary - Phagocytosis and Bacterial Pathogens

Phagocytes are one of the body's most important defensive systems against infection and an important topic for microbiology courses. An animation of phagocytosis is an excellent learning tool; it allows students to see how the various stages work sequentially, as well as providing visual reinforcement for important concepts such as lysosome function, phagolysosome formation, and oxidative burst.

The ability to actively defend against phagocytosis through specific virulence mechanisms is crucial to the success of a number of pathogens. This tutorial uses plague and tuberculosis as examples of two bacterial diseases that attack macrophages extracellularly and intracellularly, respectively. Virulence mechanisms differ markedly, but in both cases phagocytosis is blocked, and the pathogen can survive and grow at the expense of the phagocyte.

This interactive Flash tutorial was designed to help microbiology students (and other biology students) visualize the process of phagocytosis in macrophages and to see how Yersinia pestis and Mycobacterium tuberculosis interfere with this process. Pop-up boxes provide information about specific virulence factors and other information.

A worksheet includes 22 questions which can be answered with information from the tutorial. Instructors may choose to select a subset of these questions as a student exercise. The curriculum portion of this resource may be found at http://www.microbelibrary.org/FactSheet.asp?SubmissionID=787

The tutorial can be used in two different ways— for maximum benefit, I recommend both:
(i) as a visual enrichment during classroom presentations, and
(ii) as a homework exercise. The attached worksheet can be printed out by students or modified and handed out by the instructor. All the information needed to answer the questions can be found in the tutorial.

The activity is posted at the following URL: http://www.sp.uconn.edu/~terry/Common/phagocytosis.html