UBDOMAIN 211.2 – CLINICAL MICROBIOLOGY LABORATORY
Competency 211.2.2: Bacteria – The graduate identifies the structure, function, and transmission of bacteria and their role in pathogenesis; recognizes how bacteria can be beneficial or detrimental (or both) to humans; and solves cases involving how bacteria spread in humans.
Competency 211.2.9: Techniques and Procedures – The graduate uses appropriate techniques or procedures for interacting with microorganisms in a clinic, laboratory, or community setting; utilizes basic laboratory techniques for identifying microorganisms; demonstrates proper laboratory techniques in microbiology, including sterile technique, staining techniques, aseptic technique, and chemical indicators; and recognizes types of culture media and when to use each.
Objective 211.2.2-04: Differentiate between specified types of bacteria-caused disease.
Objective 211.2.9-17: Use a specified differential staining technique in a laboratory setting.
Introduction:
Download the attached lab manual at the bottom of the page. Access “Experiment 5: Differential Staining.” Be sure to read the entire experiment and organize time, materials, and workspace before beginning. Remember to review the safety sections and to wear goggles when working with chemicals.
In this lab you will view images of Gram stains performed on Lactobacillus, Staphylococcus aureus, E. coli, and yeast. The images are found in the attached lab manual under the Procedures section of Exercise 1 in the Differential Staining experiment.
Task:
Upon completion of the lab, write a brief essay (suggested length of 1–2 pages) in which you:
A. Describe the differences between gram-positive and gram-negative cell walls.
B. Explain what causes gram-negative bacteria to stain pink.
C. Explain what causes gram-positive bacteria to stain purple.
D. Explain the purpose of iodine in the Gram stain procedure.
1. Define what a mordant is.
E. Explain the purpose of acetone-alcohol in the Gram stain procedure.
F. Identify which organisms stained gram-positive.
1. Identify an infection most commonly associated with each identified organism (the organism can be probiotic, not necessarily the cause of the infection).
G. Identify which organisms stained gram-negative.
1. Identify an infection most commonly associated with each identified organism (the organism can be probiotic, not necessarily the cause of the infection).
H. When you use sources, include all in-text citations and references in APA format.
Note: For definitions of terms commonly used in the rubric, see the attached Rubric Terms.
Note: When using sources to support ideas and elements in a paper or project, the submission MUST include APA formatted in-text citations with a corresponding reference list for any direct quotes or paraphrasing. It is not necessary to list sources that were consulted if they have not been quoted or paraphrased in the text of the paper or project.
Note: No more than a combined total of 30% of a submission can be directly quoted or closely paraphrased from sources, even if cited correctly. For tips on using APA style, please refer to the APA Handout web link included in the General Instructions section.
