Gram Neg Differential Dx Chart

Question 1

What gram neg are lactose positive (3)?

Answer 1

E. Coli
Enterobacter cloacae
Klebsiela pneumonia

Question 2

What gram neg are lactose negative (4)?

Answer 2

Pseudomonas aerugninosa
Shigella
Salmonella
Proteus vulgaris/mirabilis

Question 3

What gram neg are H2S negative (2)?

Answer 3

Pseudomonas
Shigella
Note: these are also Lactose negative

Question 4

What gram neg are H2S positive (2)?

Answer 4

Salmonella
Proteus vulgaris/mirabilis
Note: these are also lactose negative, glucose positive, and gas producing

Question 5

What gram neg H2S negative are...
glucose negative (1)?
glucose positive (1)?

Answer 5

glu neg: pseudomonas

glu pos: shigella

Question 6

What gram neg H2S positive are…
urease negative (1)?
urease positive (1)?
motile (1 same as above)?

Answer 6

urease neg: salmonella
urease pos and motile: proteus vulgaris/mirabilis
Note: these are also glucose positive and gas producing