Broad base vs narrow base fungi

Discussion in 'Step I' started by anbuitachi, Feb 4, 2013.

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  1. anbuitachi

    anbuitachi ASA Member 7+ Year Member

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    Can someone explain what the difference is please? Lecturer said one is broad based, other has narrow base. But I'm not sure what that means. And I couldn't find good answers on google. Cause for something to bud off doesn't the base eventually have to get narrow?!? Confused.
     
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  3. Phloston

    Phloston Lifetime Donor 5+ Year Member

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    Broad-based budding = Blastomyces dermatitidis

    Narrow-based budding = Cryptococcus neoformans

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    As far as I'm aware, per imaging, you'll see the budding occur along what appears to be the whole diameter for broad-based, so the widest part of the budding complex is at the axis of cytokinesis.

    Don't worry about the imaging for narrow-based. Know that narrow-based budding = Cryptococcus just in case a vignette mentions it, but if they show you an image, it will be a white circular prominent polysaccharidic capsule in surrounding India ink stain, or they'll show you red mucicarmine staining. But also be aware of latex agglutination for Crypto.
     
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  4. withrye

    withrye 7+ Year Member

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    The "base" refers to the amount of contact between two buds. This is to say that broad based buds are practically entirely connected at the base before splitting off. Yes, you MAY see some Blasto organisms at a narrow stalk right before they split, but this is about the classic, textbook histology. Narrow based buds, however, show a clear "stalk" or narrow zone from where they're splitting.
    http://tiger.kobiljak.msu.edu/WebSites/Web_Path/webpath/microbio/microbe/mic-fung.htm
    http://www.cap.org/apps/docs/cap_today/1210/Fig-3.jpg

    I think it's most helpful to remember that Blastomyces is classically "broad based," while many other fungi can be considered narrow based. Histoplasmosis, for instance, is also narrow based budding yeast. You're rarely (never?) going to need to make a fungus diagnosis based on the image alone; more often the patient presentation will make itself helpful as to which organism is most likely.
     
  5. anbuitachi

    anbuitachi ASA Member 7+ Year Member

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    thanks for your responses!! super helpful
     
  6. lulafroes

    lulafroes

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    Don't forget that Paracoccidioides brasiliensis is also a narrow-based budding yeast. The difference is that, in this case, there are many buddings in the same cell, i.e., it is a multiple narrow-based budding yeast, unlike Cryptococcus neoformans and Blastomyces dermatitis, which may have only a single budding daughter cell, if any.
     
  7. Phloston

    Phloston Lifetime Donor 5+ Year Member

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    Cheers. Will be sure to remind myself of that 4.5 yrs ago.
     

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