Results- Gram stain:gram-positive cocci, catalase test-negative, BEA+/+, hemolysis-beta, bacitracin-resistant

1) Identify Your unknown organism(Genus & species)

2) what is the critical importance of this work

3) Describe the tests you "performed" on your unknown beginning with Gram's stain.

4)Describe in detail the appearance of all results and how you determined the outcome of each result.

5)After you made your initial observations, what were the likely candidates for the organism you have.

The organism is Enterococcus Faecalis

Step-by-step explanation

1) Identify Your unknown organism(Genus & species)

The organism is Enterococcus faecalis

2) what is the critical importance of this work

The importance of this work is to discard other types of microorganisms so we will only have a specific organism remaining and it will be our agent we are looking for.

Questions 3 and 4:

First, I will do gram staining and see if the organism is gram positive (blue) or gram negative (pink). It says we got a gram positive, so after this we have to see the shape of them, it means cocci, bacillus, rods...it says we found cocci so, it can be either staphylococcus or streptococcus and in order to differentiate them we use CATALASE test. Catalase is an enzyme of aerobic organisms. Superioxide radical is produced by bacterial metabolism and an enzyme called superoxide dismutase catalyzes superoxide radical to Oxygen or hydrogen peroxidel, then an enzyme called catalase will convert the hydrogen peroxide in oxygen and water. In catalase test we put hydrogen peroxide on slide and then add the bacteria...if we see bubbles, then the organism is catalase positive because it is producing oxygen and it expresses as bubbles. It says that our organism is catalase positive and when we have catalase negative cocci, it means the organism is streptococcus.

After this, we have to use the Blood agar in order to see hemolysis and differentiate between beta, gamma or alpha hemolytic streptococcus. Beta hemolytic bacteria will show a halo around the bacteria because beta-hemolytic bacteria lyse red blood cells. Then in beta hemolytic streptococci we have Strep pyogenes (bacitracin sensitive) and Strep agalactiae (Bacitracin resistant), however it says that our organism is BEA (Bile Esculin Agar) positive and none of them is BEA positive. BEA is selective for Enterococci and Streptococcus bovis. If our organism is BEA positive, it will dye black because this agar contains esculin that is hydrolyzed by group D streptococci (S. bovis and enterococcus). The difference between S. bovis and enterococcus is that S. bovis is not beta hemolytic and enterococcus faecalis is beta hemolytic so, our organism is Enterococcus faecalis.

5)After you made your initial observations, what were the likely candidates for the organism you have.

As mentioned above, my initial candiates were Streptococcus agalactiae, enterococcus and Streptococcus bovis.