Lab method
Citrate utilization test
Prussian blue = citrate positive (Klebsiella)
SIT-rate
High-yield clue
Simmons citrate turning Prussian blue means citrate-positive (Klebsiella, Enterobacter), while Escherichia coli stays green (negative).
Overview
A biochemical concept testing whether an organism can use citrate as its sole carbon source on Simmons citrate, raising pH and turning the indicator blue.
Classification
- Carbon-source utilization concept
- Simmons citrate medium
- Bromothymol blue pH readout
Lab & identification clues
- Green to Prussian blue = citrate positive
- E. coli is citrate negative (stays green)
- Klebsiella and Enterobacter are citrate positive
- The C in the IMViC panel
Associations
- E. coli vs Klebsiella differentiation
- IMViC panel study framing
- Enteric Gram-negative identification
Commonly confused with
- Indole test
- Methyl red / Voges-Proskauer test
Frequently asked questions
What is Citrate utilization test?
A biochemical concept testing whether an organism can use citrate as its sole carbon source on Simmons citrate, raising pH and turning the indicator blue.
What is the high-yield clue for Citrate utilization test?
Simmons citrate turning Prussian blue means citrate-positive (Klebsiella, Enterobacter), while Escherichia coli stays green (negative).
What is Citrate utilization test associated with?
Citrate utilization test is associated with E. coli vs Klebsiella differentiation, IMViC panel study framing, and Enteric Gram-negative identification.
What is Citrate utilization test commonly confused with?
Citrate utilization test is commonly confused with Indole test and Methyl red / Voges-Proskauer test.
Original concept summary for coursework. Sources checked: OpenStax Microbiology 2e and NCBI Bookshelf Medical Microbiology; reviewed 2026-06. Describes vocabulary and interpretation concepts only; not a lab protocol and not for handling specimens or identifying patient isolates.