Perhaps we are changing our normal gut physiology, replacing the bacteria that have been co-selected with us during evolution. Eventually, we are doing something even worse than modifying the pathogenic bacteria Modifying the normal saprophytic bacteria in alliance with human beings through evolution. Who knows what the implications of such changes are for human health? Summers: Has anybody done any prospective studies on hospital admissions in checking the level of resistance on entry to see what level of resistance indeed does involve subsequent clinical compromise?