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CSE Spring 2008. Organism 1. XV factors not required (satellite negative) NG on MAC Non-motile Not Francisella Catalase negative β -lactamase negative Not Brucella Oxidase negative Urease negative. E. coli. H. aphrophilus. F. tularensis.
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Organism 1 • XV factors not required (satellite negative) • NG on MAC • Non-motile • Not Francisella • Catalase negative • β-lactamase negative • Not Brucella • Oxidase negative • Urease negative
E. coli H. aphrophilus F. tularensis
Everything you wanted to know about H. aphrophilus but were afraid to ask • HACEK group • Found in oropharnyx • Causes endocarditis • Does not need X and V factor
Aggregatibacter sp • Actinobacillus actinomycetemcomitans • Haemophilus aphrophilus • H. paraphrophilus – now a variant • Haemophilus sengis
Overcalling • 23% could not “rule out” a BT agent • Different treatments • Distress of infection with possible bioterror agent
Organism 2 • Oxidase negative • Urea negative • VP (25 °C) negative • Citrate (25 °C) positive
Everything you wanted to know about Y. ruckeri but were afraid to ask • Causes redmouth disease (RM) in trout • Not a normal human pathogen • 1of the 4 Yersinia species that are zoonotic
Gram stain • Bipolar appearance only seen from direct tissue staining • Yersinia will look like a “normal” GNR when stained from culture
Beware commercial identification systems are unreliable with inert organisms (i.e. Yersinia) Interpret your results with caution
Common misidentifications • Yersinia ruckeri urea negative/VP negative • Hafnia VP positive • Y. entercolitica urea positive
Consider your source • Y. entercolitica • Found in stool • Transfusion reactions • Hafnia alvei • Found in stool • Vibrio • Found in stool • Found near salt water