Aseptic technique:
The method which is used to prevent the access of microorganism during the preparation of parenteral product and their testing are called “Aseptic Technique”.
Sources of contamination:
1) Atmosphere, which is contaminated with dust, droplet and droplet nuclei becomes the breeding ground of microorganism.
2) The hands are a major means of transmitting infection.
3) Coughing, sneezing and spitting can cause contamination considerable distance.
4) The clothes which absorb dust particles are also a source of contamination. A handkerchief is the richest source of contamination.
5) The hair.
6) Unsterile equipment.
7) Working surface.
Test for Sterility:
Principle: These tests are based on the principle that if bacteria or fungi are placed in medium provided favourable conditions like nutritive material, moisture temperature, the organism will grow and their presence can be indicated by the turbidity in clear solution.
These test should be carried out in strictly aseptic condition.
Method of testing : Test of sterility may be carried out by
1) Membrane filtration method
2) Direct inoculation method
1) Direct inoculation method: The substance to be tested is aseptically drawn from the container by a suitable device and transferred to the final culture medium in the test tube. The inoculated medium (test tubes) are incubated at 20-25°C for fungi and 30-37°C for bacteria for the period of seven days. Observe the growth of micro-organism in the medium.
2) Membrane filtration method : This method is preferred in the following casesAn oil or oily preparations, ointment, A non-bacteriostatic solid, soluble powder or a liquid that possesses bacteriostatic and fungistatic properties, liquid products where volume in a container is 100 ml or more. Carry out filtration of sample under test through membrane filter having pore size of 0.45 µ and diameter of about 47 mm. After the filtration, the membrane is removed aseptically from the metallic holder and divided into two halves. The first half is transferred into 100 ml of culture media meant for fungi and incubated at 20 to 25°C for not less than 7 days. The other half is transferred into 100 ml of fluid thioglycolate medium meant for bacteria and incubated at 30 to 35°C for not less than 7 days. Observe the growth of the media.
Results :If no growth of micro-organism is found in any of the tubes, the sample is declared to have pass the test and same test is repeated for two times.