Gram-Negative Bacteria & Diagnostic Microbiology Exam 2 : Enterobacteriaceae,
Citrobacter, Escherichia, Klebsiella, Enterobacter, Salmonella, Shigella, Proteus,
Providencia, Serratia, Yersinia, Haemophilus Species, Neisseria gonorrhoeae,
Neisseria meningitidis, Moraxella catarrhalis, Urease, Indole, Lysine
Decarboxylase, Voges-Proskauer, Phenylalanine Deaminase, Triple Sugar Iron
Agar, Kligler Iron Agar, Citrate, Motility, ONPG, Lactose Fermentation,
MacConkey Agar, Chromogenic Substrate Tests, Oxidase, Nucleic Acid
Amplification, H2S Production, Hemolysis, Blood & Chocolate Agar, X & V Factor
Requirement, and Clinical Correlations of UTI, Traveler’s Diarrhea, Hemorrhagic
Colitis, Rose Spots, and Plague Exam Questions Verified and Provided with
Compete A+ Graded Rationales Latest Updated 2026
Voges-Proskauer = No color change
Phenylalanine = No color change
TSI = A/A, H2S; Citrate = Blue
Lysine = Yellow (Control tube - yellow)
Indole = No color change; ONPG = Yellow
Urea = Yellow; Motility = Positive
What is the identification?
Citrobacter species
,Which organism can cause "traveler's diarrhea" in developing countries?
E. coli
Which organism is typically MUG positive and what does a positive reaction look like?
E. coli (not E. coli 0157); fluorescence
Which organisms produce lactose positive colonies on MAC and what is the expected
appearance of the organisms?
E. coli, Klebsiella & Enterobacter are lactose + & produce red/pink colonies
Which organism causes most urinary tract infections?
E. coli
Voges-Proskauer = Pink; Phenylalanine = No color change
KIA = A/A; Citrate = Blue
Lysine = Purple (Control tube - yellow)
Indole = No color change; ONPG = Yellow
Urea = Pink; Motility = Positive
DNAse = No clearing
What is the identification?
Enterobacter species
, Voges-Proskauer = No color change
Phenylalanine = No color change
Kligler iron agar = Yellow/yellow; Citrate = Green
Lysine = Purple (Control tube - yellow); Indole = Red
ONPG = Yellow; Urea = Yellow; Motility = Positive
What is the identification?
Escherichia coli
Which of the Haemphilus species are NOT normal flora?
H. ducreyi & H. aegyptius
Which two Haemophilus species require X and V factors for growth?
H. haemolyticus (hemolytic) & H. influenzae (nonhemolytic)
Which two Haemophilus species require V factor for growth?
H. parahinfluenzae (nonhemolytic) & H. parahaemolyticus (hemolytic)
Which two Haemophilus species are porphyrin test positive (fluorescence)?
H. parainfluenzae (no hemolysis present) & H. parahaemolyticus (hemolysis)
Citrobacter, Escherichia, Klebsiella, Enterobacter, Salmonella, Shigella, Proteus,
Providencia, Serratia, Yersinia, Haemophilus Species, Neisseria gonorrhoeae,
Neisseria meningitidis, Moraxella catarrhalis, Urease, Indole, Lysine
Decarboxylase, Voges-Proskauer, Phenylalanine Deaminase, Triple Sugar Iron
Agar, Kligler Iron Agar, Citrate, Motility, ONPG, Lactose Fermentation,
MacConkey Agar, Chromogenic Substrate Tests, Oxidase, Nucleic Acid
Amplification, H2S Production, Hemolysis, Blood & Chocolate Agar, X & V Factor
Requirement, and Clinical Correlations of UTI, Traveler’s Diarrhea, Hemorrhagic
Colitis, Rose Spots, and Plague Exam Questions Verified and Provided with
Compete A+ Graded Rationales Latest Updated 2026
Voges-Proskauer = No color change
Phenylalanine = No color change
TSI = A/A, H2S; Citrate = Blue
Lysine = Yellow (Control tube - yellow)
Indole = No color change; ONPG = Yellow
Urea = Yellow; Motility = Positive
What is the identification?
Citrobacter species
,Which organism can cause "traveler's diarrhea" in developing countries?
E. coli
Which organism is typically MUG positive and what does a positive reaction look like?
E. coli (not E. coli 0157); fluorescence
Which organisms produce lactose positive colonies on MAC and what is the expected
appearance of the organisms?
E. coli, Klebsiella & Enterobacter are lactose + & produce red/pink colonies
Which organism causes most urinary tract infections?
E. coli
Voges-Proskauer = Pink; Phenylalanine = No color change
KIA = A/A; Citrate = Blue
Lysine = Purple (Control tube - yellow)
Indole = No color change; ONPG = Yellow
Urea = Pink; Motility = Positive
DNAse = No clearing
What is the identification?
Enterobacter species
, Voges-Proskauer = No color change
Phenylalanine = No color change
Kligler iron agar = Yellow/yellow; Citrate = Green
Lysine = Purple (Control tube - yellow); Indole = Red
ONPG = Yellow; Urea = Yellow; Motility = Positive
What is the identification?
Escherichia coli
Which of the Haemphilus species are NOT normal flora?
H. ducreyi & H. aegyptius
Which two Haemophilus species require X and V factors for growth?
H. haemolyticus (hemolytic) & H. influenzae (nonhemolytic)
Which two Haemophilus species require V factor for growth?
H. parahinfluenzae (nonhemolytic) & H. parahaemolyticus (hemolytic)
Which two Haemophilus species are porphyrin test positive (fluorescence)?
H. parainfluenzae (no hemolysis present) & H. parahaemolyticus (hemolysis)
