Antibiotics
The paradoxical effect or Eagle phenomenon (named after H. Eagle who first described it) refers to an observation of an increase in survivors, seen when testing the activity of an antimicrobial agent. Initially when an antibiotic agent is added to a culture media, the number of bacteria that survive drops, as one would expect. But after increasing the concentration beyond a certain point, the number of bacteria that survive, paradoxically, increases.
One of the explanations could be that as the concentration is too high, the agent might be self-antagonising the receptor with which it binds (penicillin binding proteins, for example, in the case of a penicillin). Another explanation could be that the antimicrobial agent precipitates out of solution, so activity is either not seen, or that the colorimeter is detecting crystals of an antimicrobial.
Read more about this topic: Paradoxical Reaction
Famous quotes containing the word antibiotics:
“Even diseases have lost their prestige, there aren’t so many of them left.... Think it over ... no more syphilis, no more clap, no more typhoid ... antibiotics have taken half the tragedy out of medicine.”
—Louis-Ferdinand Céline (1894–1961)