Evolution: 4 Forces
Mutation
Migration (genes moving via many processes) Natural selection Genetic drift: random sampling, more important in small populations Natural selection model
Let S = population of susceptible bacteria Let R = population of resistant bacteria What if there are 2 environments:
With antibiotics
Without antibiotics Resistance management: the R's will
lose if exposed only rarely to
antibiotics
Let q = fraction of time exposed to
antibiotics Another model
Let U=uninfected hosts, S = infected by sensitive bacteria , R=infected by resistant Worry: Hosts aren't so simple
Hope: this doesn't matter Worry: Who's treated, when? Hope: get insight from simple case
Force of infection:
Will R increase when it's rare?
Find U if R=0 (set
(This is an S only world)