Case Study 3

Dead Cattle, bloated, with epistaxis

Correct!

Question 4 of 8

If your cattle are indeed infected with Bacillus anthracis what would you expect as a result of your Gram-stain?

A.Gram positive rods


Gram-stain of B. anthracis

As a Gram-positive bacterium, B. anthracis retains crystal violet and appears purple while a Gram-negative bacterium would appear pink.

The pinkish substance around the bacterium constitutes the capsule. This capsule is important because it is "antiphagocytic". It prevents phagocytes (cells of the immune system) from destroying the bacteria by engulfing them.

B. Gram negative rods

Gram-negative bacteria appear pink and gram-positive appear purple.

Bacilli are referred to as rods (above) while round bacteria are referred to as cocci (below.)
C. Gram positive cocci

D. Gram negative cocci


The Biology Project
University of Arizona
Tuesday, August 4, 1998
Contact the Development Team

http://www.biology.arizona.edu
All contents copyright © 1998. All rights reserved.