narrowed down 1 of my unknowns help with other...

About microscopic forms of life, including Bacteria, Archea, protozoans, algae and fungi. Topics relating to viruses, viroids and prions also belong here.

Moderators: honeev, Leonid, amiradm, BioTeam

Post Reply
chrissy0022
Garter
Garter
Posts: 9
Joined: Sat Apr 14, 2012 2:10 am

narrowed down 1 of my unknowns help with other...

Post by chrissy0022 » Sat Apr 21, 2012 12:47 pm

Did enterotube on Gram - and it is E. coli.
gram negative 3.jpg
Gram negative Stain- E. coli



Down to 2 possibilities for Gram + S. epidermis or M. luteus

Growth on MSA plate and no yellow so now waiting to do a VP test to figure out which of these bacterias it is

gram positive cocci.jpg
Gram positive


Any ideas?

JorgeLobo
Coral
Coral
Posts: 424
Joined: Mon Nov 17, 2008 12:12 am

Re: narrowed down 1 of my unknowns help with other...

Post by JorgeLobo » Mon Apr 23, 2012 9:50 pm

Think I'd run an oxidase before Voges Proskauer is the test to seprrate Stpahylococcus spp. from Micrococcus spp. Staph can be neg on VP so only a + test is differentiating. I understand nNegative or weak oxidase with Microccocus spp. have been reported so here too a + test is most conclusive.

chrissy0022
Garter
Garter
Posts: 9
Joined: Sat Apr 14, 2012 2:10 am

Re: narrowed down 1 of my unknowns help with other...

Post by chrissy0022 » Tue Apr 24, 2012 12:46 am

I am following the flow chart we have been given and the next step is a VP test...
Untitled1.png

JorgeLobo
Coral
Coral
Posts: 424
Joined: Mon Nov 17, 2008 12:12 am

Post by JorgeLobo » Tue Apr 24, 2012 1:57 am

Thanks - not seen VP used so prominently in this context.

User avatar
canalon
Inland Taipan
Inland Taipan
Posts: 3909
Joined: Thu Feb 03, 2005 2:46 pm
Location: Canada

Post by canalon » Tue Apr 24, 2012 10:42 am

I imagine that in a case where students are given a number of unknown derived from a limited set that can be grown in the teaching lab, the chart that they are given is not one that is a realistic representation of how any given species would be identified in the wild. It is more like a dichotomous key (not really if you look at hemolysis here :) ) carefully crafted to separate the different candidates from one another in a minimum number of steps and at minimal cost. Usually this kind of lab is used to give students a feel for the different kind of tests that can be done and some practice with lab techniques rather than teach them a rational diagnosis tool that would be used in medical microbiology.
Patrick

Science has proof without any certainty. Creationists have certainty without
any proof. (Ashley Montague)

JorgeLobo
Coral
Coral
Posts: 424
Joined: Mon Nov 17, 2008 12:12 am

Post by JorgeLobo » Tue Apr 24, 2012 11:02 am

Good point

chrissy0022
Garter
Garter
Posts: 9
Joined: Sat Apr 14, 2012 2:10 am

Re: narrowed down 1 of my unknowns help with other...

Post by chrissy0022 » Thu Apr 26, 2012 4:43 am

My second Unknown should have been S. Epidermis but I had a negative result on My VP Test....leading me to conclude that it was M. Luteus...
and ideas why that would happen?

JorgeLobo
Coral
Coral
Posts: 424
Joined: Mon Nov 17, 2008 12:12 am

Re: narrowed down 1 of my unknowns help with other...

Post by JorgeLobo » Thu Apr 26, 2012 8:30 pm

Why what would happen?

chrissy0022
Garter
Garter
Posts: 9
Joined: Sat Apr 14, 2012 2:10 am

Re: narrowed down 1 of my unknowns help with other...

Post by chrissy0022 » Fri Apr 27, 2012 2:24 am

Why I got a negative result on my VP test

JorgeLobo
Coral
Coral
Posts: 424
Joined: Mon Nov 17, 2008 12:12 am

Re: narrowed down 1 of my unknowns help with other...

Post by JorgeLobo » Fri Apr 27, 2012 10:16 am

"Should have been S. epidermidis" -why do you say this? Is this what your instructor said?

chrissy0022
Garter
Garter
Posts: 9
Joined: Sat Apr 14, 2012 2:10 am

Re: narrowed down 1 of my unknowns help with other...

Post by chrissy0022 » Sat Apr 28, 2012 2:46 am

yes that is what she said that is was S. epidermis...

JorgeLobo
Coral
Coral
Posts: 424
Joined: Mon Nov 17, 2008 12:12 am

Re: narrowed down 1 of my unknowns help with other...

Post by JorgeLobo » Sun Apr 29, 2012 12:09 pm

Suppose youncould defend that this is a nonroutine test in this context. You might run it again with controls.

Post Reply

Who is online

Users browsing this forum: No registered users and 1 guest