hgheith
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What is the mechanism behind consistant infections of pseudomonas in cystic fibrosis pt's?
Why does this bug like their lungs specifically?
thanx
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| kingsofke
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No its not that . Actually pseudomonas occurs in clinically more susceptible individuals which have their immunity down. Like CGD and ICU patients .CF patients have damaged lungs due to mucus inspissation and recurrent non-pseudomonal infections even.
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| hgheith
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I agree, also burn and wond infections and even otits externa.
But there is a mechanism for their infection of CF pt's that is unique to this bug. I do not have the answer but this is a relavent question.
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| ssrpk
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well i agree with mr.king ,it's primarily due to lowered host defenses which in case of cystic fibrosis is due to inspissated mucus tht interferes with the normal clearance mechanisms!
alos, P.aeruginosa has this slime layer made up of glycocalyx which mediates adherence and inhibit the attachment of antibody!
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| hgheith
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I think it has something to do with that slime layer and it's capsule (biofilm) which allows formation of pulmonary microcolonies and are difficult to remove from the pt's viscous mucus.
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| hgheith
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"Some strains of P aeruginosa produce large amounts of extracellular polysaccharide. These mucoid strains usually are isolated only from patients with cystic fibrosis. The role of these polysaccharides in the pathogenesis of P aeruginosa chronic lung infections is unknown, but they may impede phagocytosis and impair diffusion of antibiotics and thus facilitate colonization and persistence."
http://gsbs.utmb.edu/microbook/ch027.htm
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| bactitech
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Pseudomonads live in water. Many CF patients use inhalers. If not properly cleaned, Pseudomonads can live in these devices. They are hardy bugs and thrive at a wide range of temperatures (Ps. aeruginosa can live at 42 degrees C, which is a differential test for identification, as other strains do not. They are a problem in hot tubs also, but I digress).
Another big problem organism for CF patients is Burkholderia cepacia. If we isolate this organism (usually always from CF patients) we forward the organism to U. of Michigan, when they are serogrouping them.
http://tinyurl.com/9hb8f
If any of you are involved with CF patients in the future, please have your micro labs forward their isolates to this laboratory (information on page above). According to this page, there is a multi-resistant Ps. aeruginosa laboratory at Columbia Presbyterian in NYC. There is a lot of work going on to tame these bugs.
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| hgheith
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Burkholderia cepacia? Is it the same as pseudomonas cepacia? I read about this same organism on the website I provided, I just wanted to know if it's the same organism or a new one?
thanx
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| bactitech
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It used to be called Pseudomonas cepacia, but the taxonomists that fool with bacterial names decided to change it a few years ago to Burkholderia cepacia. The latter is how we report it out in cultures now. Micro labs usually try to keep up with all the new names, but it throws the docs for a loop for awhile.
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| hgheith
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thank you, and it is confusing!
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| bactitech
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Some organisms I've reported out have changed their names 2-4 times over the 31 years I've worked in micro.
Pseudomonas maltophilia ---> Xanthomonas maltophilia ---> Stenotrophomonas maltophilia.
Hemophilus vaginalis ---> Garnerella vaginalis
Neisseria catarrhalis ---> Moraxella catarrhalis
There are lots of others, but my brain is fried after working tonight and I can't remember any more.
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| mjl1717
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Thank You Gatekeeper!
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| bactitech
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(Oops - should have spelled it "Gardnerella vaginalis")
Also, Neisseria catarrhalis went to Branhamella catarrhalis and THEN went to Moraxella catarrhalis.
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