microdoubts
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Hello everyone, how great I found you  OK, I have to do detective work and figure out what my unknown is. I have done tests but I am still very confused. Here are the results: Gram negative Faluctative anaerobe? Rods Motility + Carbohydrate fermentation (acid/gas): Lactose: +,+ Sucrose: +,- Glucose: +,+ Mannitol: +,+ Sorbitol: +,+ Dulcitol: -,- Xylose: +,+ Maltose: +,- Arabinose: +,+ SIM: hydrogen sulfide- indole:- motility: + Gelatinase: - Catalase: + IMViC Methyl-red: + Voges-Proskaeur: - Cotrate: + EMB: + ENDO: + Phenylalanine: - Urease: + I am so confused  According to Bergey's. it is Citrobacter freundii, but hydrogen sulfide for it is + and mine was -. Any tips on how to determine this is the one, anything specific I should look for? Thanks
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| bactitech
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Hmmmm, interesting reactions. I found this article:
http://www.pubmedcentral.nih.gov/articlerender.fc...
You could have some other weird Citrobacter. I don't have a chart with percentages of H2S positive-ness of C. freundii in front of me. Too bad you didn't set up decarboxylases (ornithine and lysine, maybe arginine). Those can sometimes help with speciation.
Motility pos rules out Klebsiella. Lactose pos puts you into Escherichia/Klebsiella/Enterobacter/Citrobacter/Serratia. However, the indole neg rules out E. coli; VP neg rules out Enterobacter, urea pos rules out Serratia, which only leaves Citrobacter. You'd probably have to go to some sort of commercial system or more sugars. I don't know all the sugar reactions off the top of my head except lactose.
What did it turn out? I assume you're done with it by now.
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Clinical Microbiology since 1974
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