[smhost]

From that same paper:

> In hospitals, both modelling and analysis of the correlations between antibiotic resistance and variation in antibiotic use show that alterations in antibiotic use can cause rapid changes (in the order of days to months) in the frequency of resistance. By contrast, when the fitness cost of resistance is the main driving force behind its reversal, the rate of change is expected to be much slower (months to years).

I think what that means is that hospitals are able to create more selective pressure by rotating through different kinds of antibiotics.