Lab test

CNA Blood agar

Selective and Differential

Selective for Gram positive

Hemolysis break down of red blood cells

Mannitol Salt

Selective and Differential

Selective: Salts inhibit growth except Staphylococcus. Differential: ability to ferment mannitol to acid causing color change of agar to yellow.

EMB: Eosin Methylene Blue

Selective and Differential

Selective: Gram negative will grow. Differential:

MacConkey’s Agar

Selective and Differential

Selectiv: Gram negative. Differential: ability to ferment lactose to acid resulting in pink. High lactose fermentation results in pink precipitates in agar.

Identify E. coli growing on EMB

Metallic green

Identify E. coli growing on MacConkey

Pink precipitate into agar

Mannitol fermentation & production of acid or not.

Identify S. aureus

Identify Staphylococcus

Yellow halo: S. aureus and produces acid

No color: not S. aureus and no acid

Catalase Test

ability to grow in presence of oxygen

Oxidase Test

To see if the bacteria can perform aerobic respiration

Phenol Red broths

Testing for fermentation of specific sugars with acids causing color change from red to yellow

Citrate Test

To determine if citrate is fermented and the sole source eof energy

Phenylalanine Deaminase Test

removal of the amine group by deamination

Gelatin Hydrolysis

breakdown of protein gelatin to see if enzymes are present

Urea Hydrolysis

breakdown of urea protein into ammonia