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  #1  
Old 11-05-2012
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Bacteria MacConkey's Agar Bacteria!

A patient 45 years old presented to a clinic with c/o fever, night sweats, weight loss of 15 kg in last 2 months and anorexia. More detailed history reveals h/o hemoptysis and contact positive for tuberculosis. PPD skin test is positive and on further work-up of sputum, organisms grow in MacConkey's agar after 24 hrs. How would the organisms be characterized?
A. Acid-fast, anaerobic, gram +ve rods
B. Partially acid fast, branching gram +ve rods
C. Gram -ve facultative anaerobes
D. Acid-fast, obligate aerobic, gram +ve rods
E. Oxidase +ve, gram -ve, obligate aerobes
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  #2  
Old 11-05-2012
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(D) TB likes the Apex, which is Aerobic. It is a Gram+. Acid-Fast, stain with Ziehl-Nielhsen
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Old 11-05-2012
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I will go for C
Suspicious for klebsiella
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Old 11-05-2012
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C......I think it's enterobacter sp.
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Old 11-05-2012
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I agree D.

H/O suggests TB .. But about MacConkeys ???

Think MAcConkey medium is both selective and differential medium .., I still want to go with D ..
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Old 11-05-2012
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D. Acid-fast, obligate aerobic, gram +ve rods
klebsiella
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Old 11-05-2012
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I excluded mycobacterium cause its not growing on Macconkeys and in 24h
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Old 11-05-2012
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my answer is E..........klebsiella(remembered doin similar one)

thanks


oops....sorry changing to C----klebsiella not an aerobe

Last edited by venky2600; 11-05-2012 at 08:28 AM.
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Old 11-05-2012
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Doubt ??

Does klebsiella produce granulomas ( k.granulomatis ... Does it get its name from producing granulomas ??? )

I also thought mycobacteria coz 15 kg weight loss in 2 months ? Unless you induce TNF alpha ??

If klebsiella produces granulomas , then it could be the answer ...
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Quote:
Originally Posted by alice View Post
Doubt ??

Does klebsiella produce granulomas ( k.granulomatis ... Does it get its name from producing granulomas ??? )

I also thought mycobacteria coz 15 kg weight loss in 2 months ? Unless you induce TNF alpha ??

If klebsiella produces granulomas , then it could be the answer ...
Question stem definitely describes TB but according to laboratory data Mycobacterium cant be the organism (it doesn t grow on Macconkey and it needs more than 24 hs)
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Klebsiella doesnt produce granulomas it causes abscess formation and cavitation as far as i remember
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Quote:
Originally Posted by alice View Post
Doubt ??

Does klebsiella produce granulomas ( k.granulomatis ... Does it get its name from producing granulomas ??? )

I also thought mycobacteria coz 15 kg weight loss in 2 months ? Unless you induce TNF alpha ??

If klebsiella produces granulomas , then it could be the answer ...
k.granulomatis(aka calymmatobacterium granulomatis)-----causes granuloma inguinale(donovanosis).......produce ulcerations not granulomas i guess

as @medicalexaminer said ,case presented here is of T.B ,but mackonkey agar make klebsiella right choice IMO
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  #13  
Old 11-05-2012
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@Medicalexaminer: Yeah .. MacConkeys is the differential for among gram negatives ones only ... Dint know that !

( I thought if it was to differentiate , it wouldn't take so much time as to grow ... And the TNF alpha as well .... But never mind !! )

Last edited by alice; 11-05-2012 at 09:01 AM.
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Quote:
Originally Posted by alice View Post
@Medicalexaminer: Yeah .. MacConkeys is the differential for gram negatives ones ... ( I thought if it was to differentiate , it wouldn't take so much time as to grow ... And the TNF alpha as well .... But never mind !! )
no..not only that one...klebsiella too is PPD +ve...
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Correct Answer CC is correct!!

Thanx for playing so well frens..................many of you cracked this..........though TB seems to be true, it doesn't grow on MacConkey's agar, and it's a slow grower 2-4 wks in L-J medium...............since contact is +ve for TB, this exposure could easily reveal PPD +ve in this patient........MacConkey's agar is selective for Gram -ve enterobacteia and differential to distinguish lactose fermenters from non-fermenters..............Klebsiella produces a similar clinical picture to PTB...........thanx.
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