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patogenecity determination of microbs - (Nov/29/2008 )

Dear friends
any body knows how can we diffrenciate between patogenic and non-patogenic microbs? i mean is there any method to identify the patogenecity of microbes?


I don't get what you exactly mean. There is no simple test to determine if a microbe is a pathogen or not. Pathogens have been classified from the disease and not the other way around. A pathogen is a pathogen for its ability to get the host sick, it depends on several different virulence factors and/or toxins. You won't be able to know if certain bacteria is a pathogen until it get the host sick (and it also depends on the host species and immune system). Even worst! Some pathogens "are not" pathogens until they move from one part of the body to another, they are also called normal flora when they are in the right place, and they are called opportunistic when travel and invade other places leading to disease. For instance, if you want to know if a particular microorganism is a pathogen you may need to do clinical studies or animal models, or isolate it from a suspicious host and follow the Koch postulates.

Probably you could study the entire genome and proteome of that microbe and match certain genes/proteins with associated toxins or virulence factors, but that is a loooong way to do it and there is a big chance that homology won't necessarily end up with a real and conclusive result (gene expression differences, epigenetics. attenuating factors...). Specially because of all genetic variations in virulence genes among the wide variety of pathogens and again, host environment.

I hope this answer your question.