Guidelines for LRN Advanced
Sentinel Laboratories
MDH Flow Chart for Rule-out and Referral of Francisella tularensis
Colony Morphology on Chocolate Agar


Slow growing; 48 hours for visible growth
Small, shiny, gray, flat colony with entire, smooth
edges
May grow initially on SBA but unlikely to grow on
subculture due to cysteine requirement

Gram Stain Morphology
Very tiny, faintly staining, pleomorphic, gram
negative coccobacilli
Very tiny, faintly staining
gram negative
coccobacilli
Bacteria not a very tiny,
faintly staining gram
negative coccobacilli
Not F. tularensis
Oxidase
Positive
Negative
Not F. tularensis
X and V Factor
Rule Out Haemophilus spp.
(satelliting with S.aureus or X&V)
X and V Factor
Identified
as Haemophilus spp.
Haemophilus spp. ruled out
NotVF.
tularensis
X and
Factor
(to rule-in/out
Haemophilus spp.)
X and V Factor
β-lactamase
X and V Factor
(to rule-in/out
Haemophilus
spp.)
Positive
X and V Factor
Other key F. tularensis
reactions – run these if
available in your lab:
Urea Nitrate -
08/03/2015
Negative
Not F. tularensis
REFER ISOLATE:
Cannot Rule Out F. tularensis
Call MDH-PHL at 612-282-3723
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