Micro Unknown

Hi everyone! I need your help IDing my unknown.

I ran some tests and here are the results:

1. Starch Hydrolysis: positive

2. OF Glucose: negative

3. Fermentation Tube: Glucose: positive, gas negative. Lactose: negative, gas negative. Sucrose: positive, gas negative

4. Citrate: negative

5. Urease: positive, slow

6. Phenylalanine: negative

7. Hydrogen sulfide: negative

8. Motility: negative

9. Ornithine: negative

10. Indole: negative

11. Oxidase: negative. (Although I'm not that sure cause it only turned blue. not pink to blue to black.)

12. Catalase: posiive

13. MRVP: negative

14. Gelatin Hydrolysis: positive

15. Nitrate Reduction: positive

I did gram stain it couple of times and its Gram negative rod. Not 100% sure since I'm not that confident.

And if you have links it would be highly appreciated.

Thanks in advance. God Bless.

[microwow]

and also, whenever i test it for growth, the bacteria floats on top of the liquid media.

[Cherish]

You should use the chart provided in your lab to get your unknowns.

http://www3.kumc.edu/aamsa/subjects/...flow-chart.jpg

http://www3.kumc.edu/aamsa/subjects/...flow-chart.jpg

[microwow]

I checked those websites already. Thanks.

I'm down to Shigella and Proteus. Which to choose? I can't fail this one. Help! Please.

[iPink, BSN, RN]

Shigella wasn't one of our unknowns, but Proteus was. Based on your results it doesn't seem like you have Proteus. Proteus is Citrate positive, Urease positive, has motility, Hydrogen sulfide positive. In fact it's positive for all tests except for VP test and PRL test.

[K nurse-one-day]

We just did ours last week. it's hard huh? you should choose shigella

[shortnorthstudent]

I cannot help you, but want to wish you loads of luck figuring it out. I'm a few weeks behind you in micro. We start on our unknowns in another week. My understanding though is that we have to identify 2 - starting out in a mixed sample and that one will be gram+ and the other gram-.

I'm terrified of this. We were told if we didn't get at least 1 of them correct, we fail the class (even though it's only 20% of our grade) no matter how well we do in the rest of the course.

[microwow]

I'm confused with my interpretations. I did Citrate and OF glucose test last week (TUE) and read the results the next day. I got both negative reaction. When I checked the test tubes this afternoon (MON), the citrate agar turned blue which is positive, and OF glucose turned both yellow meaning Fermenter right?!

Now, I'm confused which interpretion do I follow? The 24 hour incubation day or the longer Incubation time?

I'm so not a happy camper right now.

Thanks for your help.

I think it's Proteus.

[Jack245]

Almost a week seems a bit long. That might cause false results. However, I can't help you more than that, when I did my unknown I had an easy one, Pseudomonas. Turned my plate green.

[K nurse-one-day]

Incubation time should be more than 1 day. mine incubated for 8 days

[iPink, BSN, RN]

OP, I guess every school is different. But, when we did our Unknowns, we came back 5 days later to check our results. I don't know why they allowed you to check it the next day? Some bacteria may need to react for more than 24 hours, which is why they give you a couple of days to read your results.

If bacteria turned the Citrate blue (a positive result), yes Proteus is a possibility. However, Proteus isn't the only bacterium that yields a positive result to this test. For example, Enterobacter and Salmonella. What are the other possible bacterium you've studied?

Students shouldn't take identifying their unknowns lightly. Taking proper notes to prepare yourself should have been done, so you're not having to sweat over this.

[Jack245]

Incubation time should be more than 1 day. mine incubated for 8 days

More than one day yes. 2-3. I just distinctly remember my professor warning us against letting them incubate for too long, as it could cause false results given that the bacteria can do nearly anything given enough time.