Biology/Disk diffusion
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Question
Is the disk diffusion method measuring bacteriostatic or bacteriocidal action? Also in the evaluation of a disinfectant, the ability to kill dried spores is considered a stringent test--Why?
Hi Gillian: Thanks for your question.
There's no way to tell if the disc diffusion is bacteriostatic or -cidal until you take away the disinfectant. If the bacteria grow, then it was bacteriostatic. If they don't grow, then it's bacteriocidal.
A stringent test is one that takes the disinfectant to the extreme of killing. Spores are the hardest to kill, so killing them is a stringent test.
Hope this helps, write back if you have more questions.
FM Rollwagen, PhD
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Answers by Expert:
Florence M Rollwagen
Expertise
I can answer questions in biology, microbiology and immunology on the undergraduate or graduate level. I can also address medical and health concerns regarding alternative medicine, autoimmune diseases (lupus, MS) liver disease and intestinal problems.
Experience
I have over 20 years experience in research and teaching at the medical/graduate level, and 5 years teaching college biology and microbiology. My expertise is in microbiology and immunology, specifically the biology of cytokines and soluble immune response modifiers. I also carried out original research in blood substitutes and shock/trauma.
Organizations
American Association of Immunologists (AAI)
American Association for the Advancement of Science (AAAS)
Publications
Journal of Experimental Medicine, Journal of Immunology, Cytokine, Shock, Experimental Hematology
Education/Credentials
BS biology 1966
MS biology 1968
PhD immunology 1979
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