Question

1.            Unknown bacteria #1

Gram-positive cocci

Smooth, yellow colonies

Growth, but not clearing or change on blood agar

Positive for urease production

Positive for gelatinase production

Bubbling produced when exposed to H₂O₂

Name: ___________________________________

2.            Unknown bacteria #2

Gram-positive cocci (mainly diplococci and chains)

Encapsulated

Produces green halo around growth on blood agar

No color change with oxidase reagent

No color change in urea broth

Produces a yellow color in glucose, lactose, and sucrose phenol red tubes

Name: ___________________________________

3.            Unknown bacteria #3

              

Gram-positive cocci

Encapsulated

No bubbling upon exposure to H₂O₂

VP negative

Produces a clearing around growth on blood agar

Facultative anaerobe

              

Name: __________________________________

   

4.          Unknown bacteria #4

              

Gram-negative bacillus

Abundant white growth

Encapsulated

Positive for nitrate reduction

Simmons citrate agar turns blue

Bubbling produced when exposed to H₂O₂

Name:__________________________________

5.            Unknown bacteria #5

Gram-negative bacillus

Creamy, mucoid, round colonies

Produces a green halo around growth on blood agar

Negative for all tests using SIM agar

No color change in nitrate test after adding reagents A and B plus zinc

TSI slant turns completely yellow

Name: ___________________________________

6.            Unknown bacteria #6

              

Gram-positive bacillus

Abundant white, waxy growth

Clearing around growth on blood agar

Ferments mannitol with acid production

Green oval structures visible using endospore stain

VP negative

Name: __________________________________

Answer 1

According to the given question guidelines:

1. Gram positive cocci

Bubbling on h202 (catalase positive) : indicates staphylococcus app

No change in blood agar : indicates coagulase negative (staphylococcus epidermis, staphylococcus saprophyticus)

Urease positive, gelatinase positive

The given bacteria is : Staphylococcus saprophyticus (as epidermidis is urease negative)

2.gram positive diplococci, encapsulated and shows green halo on growth in blood (alpha hemolysis-incomplete hemolysis)

Urea negative, oxidase negative.

The unknown bacteria is PNEUMOCOCCUS.

3. Gram positive cocci

No bubbling h2O2 (catalase negative) : indicates streptococcus

Clearing around growth on blood agar : hence beta-hemolytic streptococcus.

VP negative, encapsulated, facultative anaerobe Beta hemoltic streptococcus is :: Streptococcus pyogenes.

4. Gram negative bacilli that is catalase positive and positive for nitrate reduction indicates : Enterobacteriacae family (E.coli, klebsiella)

Encapsulated, abundant white growth and Simmon citrate agar turning blue indicates : klebsiella. (E.coli is citrate negative)