Lab

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CASE REPORT: Three-year-old Jason woke up at 2 AM, crying and pulling on his right ear. These symptoms were similar to those he had last month and again three months earlier. In both cases, he was diagnosed with otitis media (ear infection) and was treated with antibiotics. The next day, the pediatrician explained that she suspected an antibiotic-resistant strain of bacteria and performed a tympanocentesis (sample of infected fluid from behind the eardrum) procedure for bacterial culture to determine exactly what microorganism was causing the infection. An additional antimicrobial susceptibility test to determine the most appropriate antibiotic for treatment was ordered also. The ear fluid specimen was sent to you in the clinical microbiology lab for ID. Upon receipt, the specimen was cultured on agar media and grown in a pure culture for your determinations.

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. Streptococcus pneumoniae Streptococcus agalactiae Haemophilus influenzae

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

4/25/2021 Laboratory Simulation

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Test Result

Gram staining

Gram (+) cocci in chains

Catalase test Bubbles were not noted on slide, unknown bacteria was concluded to be catalase (-)

Blood agar hemolysis test Incomplete clearing of RBCs was noted on blood agar plate, unknown bacteria was concluded to be alpha-hemolytic

Optochin test Zone of inhibition was noted on plate, unknown bacteria was concluded to be optochin (Sensitive)

Unknown bacterium identification Streptococcus pneumoniae

Completed Dichotomous Key

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