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Hot Topic: Nocardia
8/23/2012
Welcome to Mayo Medical Laboratories Hot Topics. These presentations provide
short discussion of current topics and may be helpful to you in your practice. Our
speaker for this program is Dr. Glenn Roberts, a Professor of Laboratory Medicine and
Pathology and Microbiology at Mayo Clinic, as well as a consultant in the Division of
Clinical Microbiology. Dr. Roberts discusses the features of specific organisms under
direct microscopic examination using multiple preparations. This module examines
nocardia. Thank you, Dr. Roberts.
©2012 Mayo Foundation for Medical
Education and Research. All rights reserved.
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Hot Topic: Nocardia
8/23/2012
Thank you, Sharon for that introduction. I have nothing to disclose.
©2012 Mayo Foundation for Medical
Education and Research. All rights reserved.
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Hot Topic: Nocardia
8/23/2012
This is an ongoing presentation that focuses on the individual or groups of organisms
that are seen in the direct examination of clinical specimens.
©2012 Mayo Foundation for Medical
Education and Research. All rights reserved.
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Hot Topic: Nocardia
8/23/2012
This next slide shows you a number of stains and methods that can be used to detect
fungi even though they are not designed to do so and an astute eye can pick up
organisms using things like the Gram stain, the Wright stain and so on.
©2012 Mayo Foundation for Medical
Education and Research. All rights reserved.
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Hot Topic: Nocardia
8/23/2012
And the next slide shows you a continuation of those methods. And there are a
number of things here that you might not expect to find fungi in but if you look
closely there are times that you certainly can find them.
©2012 Mayo Foundation for Medical
Education and Research. All rights reserved.
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Hot Topic: Nocardia
8/23/2012
The next slide we are going to talk about Nocardia even though Nocardia is not a
fungus. It is a partially acid-fast bacterium and is often times seen in the
mycrobacteriology part of the laboratory or in the fungus lab. And it is an organism
that is a gram positive branching bacterium that actually shows coccobacillary forms
and forms of beading. So, you will see the branching of bacteria. They are branching
bacteria they are aerobic and they show beaded forms as you see on this slide.
©2012 Mayo Foundation for Medical
Education and Research. All rights reserved.
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Hot Topic: Nocardia
8/23/2012
The next slide is not very good but it does show in the background there that there
are bacteria that exhibit branching. If you look this happens to be a phase-contrast
photomicrograph which most people probably would not use but it does show,
nevertheless, an organism is there and you have to look very closely in the
background to see those branching bacteria. It illustrates that same point when you
look at a Gram stain. You look at some other stains where you can see the same
thing.
©2012 Mayo Foundation for Medical
Education and Research. All rights reserved.
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Hot Topic: Nocardia
8/23/2012
The next slide shows you a phase-contrast photomicrograph of a specimen, a
sputum, and there are numerous branching bacteria. And it is important to
remember that once you see a situation like this, it is not possible to distinguish
Nocardia from Actinomyces because they are both Gram positive branching bacteria.
And this is not a Gram stain, by the way, this is phase-contrast microscopy but you
would have to do a modified acid-fast stain to be able to distinguish between the
two.
©2012 Mayo Foundation for Medical
Education and Research. All rights reserved.
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Hot Topic: Nocardia
8/23/2012
So, the next slide shows you a Gram stain of Nocardia and it just illustrates the
branching bacteria and they branch at all sorts of angles.
©2012 Mayo Foundation for Medical
Education and Research. All rights reserved.
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Hot Topic: Nocardia
8/23/2012
The next one, next slide shows you some material from an abscess. And if you look
closely you can see the Gram-positive branching bacteria in there. And this is a Gram
stain and it shows you very well. And again, you cannot distinguish Nocardia from
Actinomyces.
©2012 Mayo Foundation for Medical
Education and Research. All rights reserved.
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Hot Topic: Nocardia
8/23/2012
This next slide shows you a Gram stain exhibiting numerous beading filaments of
Nocardia that also exhibit branching.
©2012 Mayo Foundation for Medical
Education and Research. All rights reserved.
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Hot Topic: Nocardia
8/23/2012
The next slide shows you an acid-fast stain and there are branching acid-fast bacteria
in here. It is important, I think to remember, that when you look at these acid-fast
smears that you look in an area where it is not so concentrated because in an area
where the stain is concentrated, almost everything looks acid-fast and if you get away
from that area out where the specimen is thin, you can recognize that some of the
filaments are stained with the acid-fast stain and some of them are not. And in this
one it just exhibits good branching and it is difficult to tell if it is partially acid-fast or
not.
©2012 Mayo Foundation for Medical
Education and Research. All rights reserved.
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Hot Topic: Nocardia
8/23/2012
The next slide came from a psoas abscess. And this is showing you an elongated
bacteria. They are very filamentous bacteria in here. You can see some beaded forms
in there. And this turned out to be a case of Nocardia.
©2012 Mayo Foundation for Medical
Education and Research. All rights reserved.
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Hot Topic: Nocardia
8/23/2012
The next slide shows another acid-fast stain and the background is very faint. But you
can see the branching in there and that is what we are looking for.
©2012 Mayo Foundation for Medical
Education and Research. All rights reserved.
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Hot Topic: Nocardia
8/23/2012
The next one shows you some material from the psoas abscess again. And there you
can see the branching bacteria that are red and they are acid-fast. But what we are
looking for are partially acid-fast bacteria. Some of the filaments will stain with the
Kinyoun stain or whatever stain you chose to use -a modified acid-fast stain. And
others will take up the methylene blue stain or the counter stain.
©2012 Mayo Foundation for Medical
Education and Research. All rights reserved.
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Hot Topic: Nocardia
8/23/2012
Now the next slide shows you what we were just talking about. If you look in the
background, you can see some branching bacteria but in the center there are some
very faint red organisms in there and those are the acid-fast ones. And there is a long
one about maybe 6:00 o’clock, a little up from the bottom. And you can see the
elongated bacterial filaments in there that retain the acid-fast stain. And then there
are some that don’t. And that is exactly what we are talking about, is the modified
acid-fast stain will show you the partial acid-fastness of Nocardia.
©2012 Mayo Foundation for Medical
Education and Research. All rights reserved.
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Hot Topic: Nocardia
8/23/2012
The next one shows you a better illustration of that and you can see the acid-fast
filaments and there in the background there are some that are not. But you can see
the beaded forms in this one just a bit.
©2012 Mayo Foundation for Medical
Education and Research. All rights reserved.
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Hot Topic: Nocardia
8/23/2012
The next slide shows you an even better example of Nocardia. What is apparent here
are the beaded acid-fast bacteria and then around near those would be the ones that
are not stained with the acid-fast stain. So you would see partially acid-fast bacteria
some stained and some do not. But the beading is very prominent.
©2012 Mayo Foundation for Medical
Education and Research. All rights reserved.
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Hot Topic: Nocardia
8/23/2012
The next slide shows you an area that you would probably not want to look in. This is
an area where it is highly concentrated and almost everything is stained in the acidfast stain. And so I would move around to another part of the field, another part of
the slide and see if I can find something that looks better than this. This kind of reemphasizes the point that we have made before in other discussions that you need to
look at the entire slide before you make a decision as to what you are going to call
something.
©2012 Mayo Foundation for Medical
Education and Research. All rights reserved.
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Hot Topic: Nocardia
8/23/2012
The next slide shows you partially acid-fast bacteria up around 10:00 o’clock and in
there are some in there that are staining kind of blue and those are the ones that
take up the background stain. So there are partially acid-fast bacteria in here.
©2012 Mayo Foundation for Medical
Education and Research. All rights reserved.
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Hot Topic: Nocardia
8/23/2012
And this is a silver stain that we use for detecting fungi. And it deposits silver around
the cell wall of organisms that it stains. And what happens is it makes the cells look
larger and they are actually easier to see. And bacteria stained with a silver stain and
this happens to be an example of Nocardia as stained with a methetamine silver
stain. And so you can’t tell if this is Actinomyces so you would have to order a
modified acid-fast stain to be able to distinguish it from Actinomyces even though
Actinomyces is not as common as it used to be.
©2012 Mayo Foundation for Medical
Education and Research. All rights reserved.
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Hot Topic: Nocardia
©2012 Mayo Foundation for Medical
Education and Research. All rights reserved.
8/23/2012
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