Antibiotics do not create resistant bacteria; they simply clear away the susceptible ones so the few already-resistant cells inherit the empty space. Under drug pressure the resistant fraction climbs generation after generation: selection turned into a number. There is a nastier route as well, horizontal transfer, where a small plasmid ring passes straight from one cell to another so resistance spreads without waiting for the next generation. The mutation rate of the strain decides how soon that first resistant cell appears at all.
Antibiotics do not create resistant bacteria; they simply clear away the susceptible ones so the few already-resistant cells inherit the empty space. Under drug pressure the resistant fraction climbs generation after generation: selection turned into a number. There is a nastier route as well, horizontal transfer, where a small plasmid ring passes straight from one cell to another so resistance spreads without waiting for the next generation. The mutation rate of the strain decides how soon that first resistant cell appears at all.
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