Bacterial Identification

Selective Media

Allows for growth of only certain organisms.

Differential Media

Produces distinct colony morphologies to help differentiate target organisms.

Gram Stain

Differentiates based on cell wall properties (gram-negative vs gram-positive)

Endospore Stain

Identifies the presence of survival structures.

Acid-fast Stain

Specifically for organism with waxy cell walls.

Oxidase

Detects Cytochrome C oxidase for aerobic respiration.

Catalase

Detects the breakdown of H2O2 into H20 and O2.

Coagulase

Identifies the ability to cause clotting to evade host defenses

Hemolysis

The breakdown of red blood cells for iron access.

Urease

Detects enzymes that raise the environment's pH.

Carbohydrate Fermentation

Identifies acid or gas production

Ornithine Decarboxylase

Determines if a bacterium produces the enzyme ornithine decarboxylase to break down the amino acid ornithine into putrescine, raising the pH.

IMViC

Four tests:

- Indole (tryptophan)

- Methyl red (presence of acids)

- Voges-Proskauer (acetoin production)

- Citrate (use of citrate)

Dichotomous Keys

A flowchart of successive questions used to narrow down an organism.

Numerical Identification

Miniaturized kits that perform many tests simultaneously, producing a code number linked to a species database

Phage Typing

Differentiates bacteria based on their susceptibility to infection by specific bacteriophages.

Serology

Uses highly specific antibodies to recognize unique antigens.

Latex Agglutination

Antibodies on beads cause visible clumping when they bind to a microbe.

ELISA (Direct)

Detects antigens in a sample through antibody binding and a visible color change

Lateral Flow Assay

A test strip where labeled antibodies bind to antigens and are pulled across a membrane by capillary action to show a positive line.

Claudograms

Diagrams that illustrate the relatedness of organisms based on sequence alignment. The length of the horizontal branches is proportional to the percent identity; shorter branches indicate organisms that are more closely related.