23  Lab 3 Aims and Overview

23.1 Aim

To understand how to identify unknown microorganisms affecting the intestinal tract using molecular and media-based techniques.

23.2 Learning Outcomes

At the end of this laboratory session, you should understand:

  • How to identify pathogens of the intestinal tract using differential and selective media.

  • How to identify pathogens of the intestinal tract using and an API-20E set of biochemical tests.

  • How to analyse and identify microbes through their ability to grow aerobically or anaerobically.

23.3 Competencies

  • Using aseptic technique

  • Pipetting

  • Anaerobic cultivation of microbes

  • Using appropriate methods to identify microorganisms (differential media, tests)

  • Documenting and reporting on experimental results and conclusions

23.4 Importance

This laboratory session aligns with lectures and reinforces material relating to pathogens of the intestinal tract, bacterial identification and phylogeny, bacterial metabolism, epidemiology and clinical microbiology.

23.5 Overview of Lab 3

In this lab session, you will be learning (or further developing your skills in) a number of key microbiology skills:

  1. You will analyse the results from the blood agar plates you streaked in the previous lab session (Task 3A)

  2. You will use a selective and differential medium to cultivate unknown intestinal pathogens (MacConkey agar, Task 3B)

  3. You will perform some biochemical assays to help identify pathogens of the intestinal tract (catalase and oxidase assays, Task 3C)

  4. You will analyse an unknown microbe’s requirement for oxygen (Task 3D)

  5. You will set up some cultures for our next lab session (inoculate Staphylococcus aureus on Mannitol Salt Agar, another selective and differential medium (Task 3E)

To prepare for Lab 3

Before attending the practical lab, you should ensure that you have read and understood:

You also must ensure that you have read and signed the safety forms, or you will not be admitted to the lab.