Methods of identification of bacteria:

1. Culture: From the sample, bacteria isolated and cultured in pure form. The colonies of different bacteria are different. The desired bacteria from the identified colony are repeatedly cultured until pure colony is obtained.
2. Colony morphology: The colonies of different bacteria differ in color, shape, size, surface, elevation, opacity, edges, etc which help in differentiation.
3. Staining: staining differentiates different bacterial properties. For example, Gram’s staining differentiates gram positive bacteria and gram negative bacteria, ZN staining differentiates acid fast and non- acid fast organisms.
4. Microscopy: Different morphological forms and characters are identified under microscope. Eg: bacillus, coccus, streptococci, diplobacillus, monobacillus, vibrio, etc.
5. Biochemical tests: different bacteria form unique metabolic products which forms basis for identification. Eg: color change indicates fermenters (acid production by sugar fermentation) and non- fermenters in MaConkey agar.
6. Serology: Detection of serum antibodies in response to antigens of bacteria.
7. Molecular detection: detect DNA or RNA of bacteria.
8. Antibiotic sensitivity test (AST): Isolated bacteria tested for antimicrobial sensitivity for selecting appropriate antibiotic for therapeutic use.