lOMoARcPSD|44532475
Lab 9 Notebook
Title: DO09 Unknown Pathogen Analysis
Objective: To identify an unknown pathogen(s) based on the given assays developed during this
course.
Notes:
• Two samples from the hospital were brought to your lab for diagnosis. After culturing the
samples on LB agar plates, another coworker began the analysis. However, due to an
emergency your coworker left the remaining work to you. Before leaving, your coworker
informs you the 2 liquid culture samples were accidentally combined before the gram
stain was started. However, the 2 cultures remain separated on LB plates for future tests.
o Goal: Correctly identify the 2 pathogens
• Gram stain shows two samples, one stained pink and one stained purple. One is spherical
shaped (purple – gram positive) and the other rod shaped (pink – gram negative)
• MacConkey Plates
o Culture A, no growth observed
o Culture B, lactose fermentation present, single colonies isolated in zone 3, E. Coli
culture growth is gram negative (only gram negative will grow on this plate;
selects between E. coli K12 and E. Coli 0157\
• BAP Plates
o Culture A – growth present but no beta hemolysis
o Culture B – streaked in two zones, growth observed in a different phenotype than
culture A; has a white film and the red part of the agar has changed color due the
lyses of the red blood cells (the red agar is clear/has a white film). Staph aureus
demonstrates beta hemolysis
• EMB Plates (differentiate between gram negative bacteria; one can ferment lactose one
cannot)
o Culture A – no growth
o Culture B – growth observed with green tint indicated it is able to ferment lactose
and is an E. Coli sample
• Catalase Test – differentiates between staph and strep
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Lab 9 Notebook
Title: DO09 Unknown Pathogen Analysis
Objective: To identify an unknown pathogen(s) based on the given assays developed during this
course.
Notes:
• Two samples from the hospital were brought to your lab for diagnosis. After culturing the
samples on LB agar plates, another coworker began the analysis. However, due to an
emergency your coworker left the remaining work to you. Before leaving, your coworker
informs you the 2 liquid culture samples were accidentally combined before the gram
stain was started. However, the 2 cultures remain separated on LB plates for future tests.
o Goal: Correctly identify the 2 pathogens
• Gram stain shows two samples, one stained pink and one stained purple. One is spherical
shaped (purple – gram positive) and the other rod shaped (pink – gram negative)
• MacConkey Plates
o Culture A, no growth observed
o Culture B, lactose fermentation present, single colonies isolated in zone 3, E. Coli
culture growth is gram negative (only gram negative will grow on this plate;
selects between E. coli K12 and E. Coli 0157\
• BAP Plates
o Culture A – growth present but no beta hemolysis
o Culture B – streaked in two zones, growth observed in a different phenotype than
culture A; has a white film and the red part of the agar has changed color due the
lyses of the red blood cells (the red agar is clear/has a white film). Staph aureus
demonstrates beta hemolysis
• EMB Plates (differentiate between gram negative bacteria; one can ferment lactose one
cannot)
o Culture A – no growth
o Culture B – growth observed with green tint indicated it is able to ferment lactose
and is an E. Coli sample
• Catalase Test – differentiates between staph and strep
Downloaded by madiba South Africa stuvia ()
