Figure 3

Stochastic simulations: (a) The effect of different rates of treatment with antibiotic 1 on the frequency of colonized patients in the absence of resistance. (b) The effects of different rates of treatment with antibiotic 1 on the frequency of patients colonized with bacteria resistant to this antibiotic without the use of antibiotic 2. Initially the frequency of patients colonized with bacteria resistant to antibiotic 1 is 10% and no patients enter the hospital carrying resistant bacteria. (c) The effect of different rates of random switching to a second drug on the frequency of resistance to the first antibiotic. Initially 10% of the patients are colonized with bacteria resistant to drug 1 and 40% of colonized patients are treated with drug 1, f = 0.40. No patients carrying bacteria resistant to drug 1 enter the hospital. (d) The effect of different rates of random switching to a second drug on the frequency of resistance to the first antibiotic. The parameters are the same as those in (c) save for the 10% of the patients entering the hospital carrying bacteria resistant to drug 1.