Multiple Choice
A pharyngeal specimen is inoculated on cystine-tellurite blood agar,modified Tinsdale agar,and MacConkey agar.After 48 hours of incubation,black colonies with a brown halo are observed on the Tinsdale agar and gray colonies are isolated from the cystine-tellurite agar.However,no growth is observed on the MacConkey agar.Which one of the following statements explains this discrepancy?
A) The MacConkey agar is most likely expired.
B) The MacConkey agar should be incubated an additional 24 hours to observe growth.
C) The pH of the media may be altered,causing an environment that is too acidic for the organism to grow.
D) No discrepancy is present;this organism does not grow on MacConkey agar.
Correct Answer:
Verified
Correct Answer:
Verified
Q1: After 48 hours of incubation,black colonies with
Q2: The isolation of a small gram-positive,catalase-positive rod
Q4: The organism that exhibits characteristic end-over-end tumbling
Q5: A middle-aged women presented to the emergency
Q6: Patients who are immunocompromised and women who
Q7: A catalase-positive,gram-positive bacillus that is not acid-fast,does
Q8: A cerebrospinal fluid (CSF)culture was performed on
Q9: Bacteria described as being coryneform have which
Q10: A gram-positive bacillus,which grew on Tinsdale agar,is
Q11: A 13-year-old girl presented to her physician