Question

QUESTION 1
When performing the urease test, the agar changes from blue to green if the organism is producing urease.
True
False

Macroscopic examination of the bacterial unknown can provide all the following except
       Colony morphology
       Growth patterns in broth
       Oxygen requirements
       Temperature preference
       Cell arrangement and shape of individual bacteria

Genotypic testing can be used to identify the presence or absence of a specific species of bacteria from a mixed sample.
True
False

QUESTION 5
All the following tests are commonly performed when identifying an unknown, gram-negative rod except
       Oxidase test
       IMViC tests
       Nitrate reduction
       Bile esculin hydrolysis
       Carbohydrate fermentation profiles

Answer 1

1. When a test in which colour changes from blue to green, the organism is utilizing CITRATE. Urease test will change colour from orange to pink. (FALSE)
2. Cell arrangement and shape are only detected on microscopy.(ANSWER) Colony morphology like colour, shape, hemolysis etc can be told. Growth pattern like swarming in Proteus can be told. Oxygen requirements can be told as organisms requiring oxygen grow at the surface and those who don't, grow at the bottom of the tube. Temperature preference can be checked if the organism grow at specific temperature or not.
3. FALSE. Genotypic testing is done in cases of viruses only.
4. Carbohydrate fermentation tests, IMViC are routinely done tests. Oxidase tests are performed to detect which organism can produce oxidase or not. For example E coli is oxidase negative while Helicobacter pylori is oxidase positive. Nitrate reduction test is also performed routinely example Kingella is nitrate negative while most are positive. Bile esculin hydrolysis is used to differentiate between Enterococcus and other streptococci. It is not for gram negative bacilli. (ANSWER).