E. faecium genes involved in ampicillin resistance as determined by M-TraM analysis.

aIndicates the gene containing the transposon insertion.bIndicates the fold-change derived from the ratio of the unselected control library to the ampicillin competitively selected library. e.g. the value 32.5 means that the relative quantity of mutants of EfmE1162_0447 in the ampicillin-selected library was 32.5-fold less than in the control library grown without selective pressure. This indicates that mutants in EfmE1162_0447 have a lower relative fitness in the presence of ampicillin than wild type cells. The value of −7.5 for EfmE1162_2487 indicates that mutants in this gene outgrow the other mutants in the ampicillin-selected library by 7.5-fold, indicating that mutants of EfmE1162_2487 have higher relative fitness in the presence of ampicillin.