Methods

METHODS

  • The clinical specimens are obtained aseptically from body fluid (blood, CSF) discharges (sputum, urine, feces).
  • To cultivate or culture microorganisms, introduce a tiny sample into a container of nutrient medium, which provide an environment in which microorganisms multiply and the  process is called as Inoculation.
  • There are different methods of inoculation for cultivating the bacteria.
      • A small droplet of culture or sample is spread over the surface of the medium with an inoculating loop or swab and then streaked over the surface according to the pattern that gradually thins out the sample and separates the cells .
      • The sample is diluted serially into a series of nutrient broth so as to dilute the number of cells sufficiently to obtain separate colonies when plating  the small volumes of several diluted samples are mixed with liquid agar that has been cooled to 45 c and mixtures are poured immediately into sterile petriplates and are allowed to solidify. The number of cells in the tubes has ample space , each cell is fixed inn place to grow into separate colonies. In this technique some of the colonies will develop deep in the medium itself and not on the surface.
    • Spread plate method - Click here for animation...
      • A small volume of liquid /diluted sample is pipetted onto the surface of the medium and spread evenly by a sterile spreading L shaped glass rod. Cells are pushed into separate areas on the surface so that they can form individual colonies.
Last modified: Sunday, 25 September 2011, 9:35 AM