kiranmayi
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A 28-year-old white female presents with a diffuse rash. The rash involves hair follicles, with apparent pustules. The patient reports a history of recent hot tub use. What are the characteristic findings regarding the responsible bacterium?
A. Colorless colonies on MacConkey agar; oxidase positive; blue-green pigment on nutrient agar
B. Colorless colonies on MacConkey agar; urease positive; blackens triple sugar iron agar
C. Colorless colonies on MacConkey agar; oxidase negative; no gas on triple sugar iron agar
D. Colored (pink) colonies on MacConkey agar; urease positive
E. Colored (pink) colonies on MacConkey agar; metallic green sheen on EMB agar
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| dxtxpx
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choice a :?:
Case is of hot tub folliculitis caused by Pseudomona
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| chemamr
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I THINK ITīS C.
AM I OK?. :roll:
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| mjl1717
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answer-a--Pseudomonas is oxidase + with blue /green pigment
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| kiranmayi
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Answer is A
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| bactitech
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Pseudomonas aeruginosa is the only organism that produces green pigment (pyocyanin). It is oxidase positive and a non-lactose fermenter on MacConkey agar (clear). The reason that it grows in hot tubs is that it will grow at 42 degrees C quite well. This is one of the differentiating characteristics of the organism, although commercial systems ID it quite well without having to sub it to this temperature.
The answer (C) could be any number of NLF's, since the oxidase reaction is negative. The oxidase reaction is KEY to ID of nonlactose fermenters. Without it, you have no map of which direction to go for identification.
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| Malaysian
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whats NLF bactitech?Also thanks for the pointer on pseudomonas.
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| bactitech
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NLF=non-lactose fermenter. Sorry about the jargon. I get carried away and use abbreviations that we use in the lab.
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