Lab 9 Notebook
VW09: Unknown Pathogen Analysis
Objective: To identify an unknown pathogen(s) based on the given assays developed during this
course.
Procedure: Evaluate the results of tests 1-7 to denote the two unknown cultures.
Notes: Two samples from the hospital were brought to your lab for diagnosis. After culturing
the samples on LB agar plates another co-worker began the analysis. However, due to an
emergency your co-worker has left the remaining work for you. Before leaving your co-worker
informs you the 2 liquid culture samples were accidentally combined before the Gram stain was
started. However, the 2 cultures remain separated on 2 independent LB plates for future tests.
Goal: To correctly identify the two unknown pathogens.
Results:
Test #1: Gram Staining
Cocci/ spherical shaped purple clusters- Gram-positive- Staph aureus or Strep.
Pink bacillus/ rod shaped chain-like structures- Gram-negative- E. Coli or Pseudomonas.
Test #2: MacConkey Plates:
Culture A: No growth observed- Gram-positive- cocci shaped.
Culture B: Growth observed, red color- Gram-negative- bacillus shaped.
Test #3: BAP Plates
Culture A: Lysed, growth occurred, brown color- beta hemolysis- region of clearing- Staph
aureus.
Culture B: growth occurred, red color- gamma hemolysis- white colonies growing on red agar-
E. coli.
Test #4: EMB Plates
Culture A: Gram-positive (growth restricted).
Culture B: Gram- negative (growth occurred)- green metallic color to the bacterial growth- E.
coli.
Test #5: Catalase Test
Culture A: bubbles formed- catalase positive-can breakdown hydrogen peroxide- Staph aureus.
Culture B: bubbles formed- catalase positive- can breakdown hydrogen peroxide.
Test #6: Oxidase Test
Culture A: no color change- oxidase negative- anaerobic.
Culture B: no color change- oxidase negative- anaerobic- E. coli.
VW09: Unknown Pathogen Analysis
Objective: To identify an unknown pathogen(s) based on the given assays developed during this
course.
Procedure: Evaluate the results of tests 1-7 to denote the two unknown cultures.
Notes: Two samples from the hospital were brought to your lab for diagnosis. After culturing
the samples on LB agar plates another co-worker began the analysis. However, due to an
emergency your co-worker has left the remaining work for you. Before leaving your co-worker
informs you the 2 liquid culture samples were accidentally combined before the Gram stain was
started. However, the 2 cultures remain separated on 2 independent LB plates for future tests.
Goal: To correctly identify the two unknown pathogens.
Results:
Test #1: Gram Staining
Cocci/ spherical shaped purple clusters- Gram-positive- Staph aureus or Strep.
Pink bacillus/ rod shaped chain-like structures- Gram-negative- E. Coli or Pseudomonas.
Test #2: MacConkey Plates:
Culture A: No growth observed- Gram-positive- cocci shaped.
Culture B: Growth observed, red color- Gram-negative- bacillus shaped.
Test #3: BAP Plates
Culture A: Lysed, growth occurred, brown color- beta hemolysis- region of clearing- Staph
aureus.
Culture B: growth occurred, red color- gamma hemolysis- white colonies growing on red agar-
E. coli.
Test #4: EMB Plates
Culture A: Gram-positive (growth restricted).
Culture B: Gram- negative (growth occurred)- green metallic color to the bacterial growth- E.
coli.
Test #5: Catalase Test
Culture A: bubbles formed- catalase positive-can breakdown hydrogen peroxide- Staph aureus.
Culture B: bubbles formed- catalase positive- can breakdown hydrogen peroxide.
Test #6: Oxidase Test
Culture A: no color change- oxidase negative- anaerobic.
Culture B: no color change- oxidase negative- anaerobic- E. coli.
