Microbiology Unknowns

[jackson145]

Does anyone remember doing clinical unknowns? I just got started on mine today. I'm certain that one of them is a + cocci, but the other one looked -. Problem is it also looked like a cocci and our teacher is only giving us rods in the - category. I went ahead and began testing for +'s. Both were catalase +, but a Gram - can be catalase +. Next, I've innoculated a Bromcresol purple slant to test for glucose fermentation. Is there a way for me to quickly check if I might have a -? Any media I ask for now that isn't in the Gram + line of testing will cause me to be docked so I'm just not sure what to do.

[Kina21]

My micro teacher had us do gram staining several times. She had us prepare like 8 slides of our unknown, hit fix them and then store them in a slide box. That way if tests started to not make sense, we could repeat some. I redid my gram stain twice because the color was in between pink and purple, looked purple to me but the teacher had doubts. When I redid it it was definitely purple. It doesn't hurt to repeat...good luck :)

[jackson145]

We can Gram stain as much as we want, but when we begin testing we have to declare whether it's + or -. After that, if you backtrack and do a test from the - side of the dichotomus key, you get docked. At that point, you lose points for each test you do opposite of what you originally said you had (Gram + or -). I think if I go ahead and name my specimen (looks like Micrococcus luteus) and I'm wrong it won't cost me any more points than getting docked to go back and try other tests. Hopefully, my gut instinct will prove correct!

[loveSol]

The gram stain is definitely the easiest way to tell if dealing with a gram - or +. Depending on the size and the orientation of the microorganism on the slide, rods can sometimes look like cocci. What you see in the microscope are in three dimensional orientations. Might be something to consider, hope it helps! I'm so glad I'm finished with micro!

[NoviceRN10]

My unknown was so easy it didn't even involve any gram staining. We used different types of medium in Petri dishes to determine what microbes we had, as well as the slant tubes too. It was supposed to be such a big deal but it was the easist 60 pts I got in the class! I hope that you figure out what you need to know without getting docked any points.

[jackson145]

Thanks to all of you for your tips. I think I've figured one out. The test results were very clear (if I didn't botch Gram stain!). I've got one more result to check Monday and then I should have them both.