Lab

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CASE REPORT: While swimming in the creek, Anna slipped and a rock cut a three-inch gash in her leg. The next day, the area around the cut was swollen and red and the pain was increasing. When she began to run a fever later in the afternoon and the wound began to throb, a friend took her to the emergency room. A specimen of pus was collected from the wound for culture. An IV was started, delivering a broad-spectrum antibiotic. Blood work showed high activity and numbers of white blood cells. Quick work by the laboratory team isolated the organism into pure culture and was provided to you on a nutrient agar slant and in a liquid broth culture tube for further investigation. Patient condition is becoming critical. Unknown bacterium identification needed STAT.

Student: ashma

Case Introduction Questions Based on the information in the case, what organism(s) could or should be suspected to cause this scenario? Select all that apply. Pseudomonas aeruginosa Staphylococcus aureus Escherichia coli

Now that a pure culture has been isolated for you, what would be a good starting procedure to begin classifying your unknown organism?

Gram staining

Collected Lab Data Test Result

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Test Result

Gram staining

Gram (-) bacilli

Oxidase test Blue color was noted on swab, unknown bacteria was concluded to be oxidase (+)

Glucose fermentation Red appearance indicates no colorimetric pH change was noted in PRB tube, unknown bacteria was concluded to be glucose fermentation (-)

Nitrate reduction Colorless reaction after zinc addition was noted in tube, unknown bacteria was concluded to be nitrate reduction (+)

Unknown bacterium identification Pseudomonas aeruginosa

Completed Dichotomous Key

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