  Ecology and evolution under changing environments are important in many
subfields of biology with implications for medicine. Here, we explore an
example: the consequences of fluctuating environments on the emergence of
antibiotic resistance, which is an immense and growing problem. Typically, high
doses of antibiotics are employed to eliminate the infection quickly and
minimize the time under which resistance may emerge. However, this strategy may
not be optimal. Since competition can reduce fitness and resistance typically
has a reproductive cost, resistant mutants' fitness can depend on their
environment. Here we show conditions under which environmental varying fitness
can be exploited to prevent the emergence of resistance. We develop a
stochastic Lotka-Volterra model of a microbial system with competing
phenotypes: a wild strain susceptible to the antibiotic, and a mutant strain
that is resistant. We investigate the impact of various pulsed applications of
antibiotics on population suppression. Leveraging competition, we show how a
strategy of environmental switching can suppress the infection while avoiding
resistant mutants. We discuss limitations of the procedure depending on the
microbe and pharmacodynamics and methods to ameliorate them.
