Question

What is the purpose of bacterial isolation and why is it necessary for medical diagnosis?

Answer 1

The purpose of bacterial isolation is to obtain pure culture of the bacteria. Bacterial isolation, purification and identification are the initial steps of bacteriological studies.

This pure culture is studied for morphology, physiology, biochemical reactions and antibiotic sensitivity of bacteria. Bacterial isolation is necessary for correct identification of pathogen and selection of suitable antibiotics against the isolated bacteria. Hence bacterial isolation is essential for correct and complete medical diagnosis.

Discussion and explanation :

Many a times we get a mixed bacterial flora in a sample. To make correct diagnosis or identify a particular bacteria we have to obtain pure culture to isolate bacteria. For this, usually streak plate method is used in which a loop full of inoculum is transferred to a culture medium and streaked for growth. After growth many characteristics such as colony morphology, colony colour, Gram staining showing morphology (Cocci or bacilli or comma shaped ) and staining pattern (Positive or negative), motility (swarming growth), sugar fermentation, catalase test, oxidase test, coagulase test, urease test, indole test etc can be implied to identify the particular bacteria.

After identifying bacteria, antibiotics can be applied to culture to look for growth inhibition (sensitivity) of the isolated bacteria to guide proper antibiotic therapy.