OBJECTIVES: The aim of the study was to determine the interplay between the plasmid-mediated qepA2 gene and multiple chromosomally mediated @entity3284 resistance determinants in the development of @entity3284 resistance in @entity526 and its influence on bacterial fitness. METHODS: @entity526 ATCC 25922 and derived isogenic strains harbouring different chromosomally mediated @entity3284 resistance determinants were electroporated with pBK- @entity2834 vector encoding QepA2. The MICs of @entity2887 were determined by standardized microdilution. The mutant prevention concentration (MPC) was evaluated. Bacterial fitness was analysed using   lacZ system competition assays. RESULTS: The @entity2177 MIC for strains harbouring the qepA2 gene was 4- to 8-fold higher compared with strains without the qepA2 gene. The qepA2 gene also increased the MPC of @entity2177 4- to 16-fold. Combination of the qepA2 gene plus two to three additional mechanisms conferred a clinically relevant resistance level. The presence of the qepA2 gene was associated with fitness costs in strains with mutations in the gyrA and/or parC genes, although the presence of an additional deletion of the marR gene compensated for this fitness cost by increasing bacterial fitness by 5%-23%. CONCLUSIONS: The additive effect of chromosomally mediated @entity3284 resistance mechanisms and the qepA2 gene led to clinical levels of @entity3284 resistance. Under competitive conditions, the qepA2 gene had a biological cost in @entity526 that was compensated for by the presence of an additional deletion in the marR gene.

Effect of the efflux pump QepA2 combined with chromosomally mediated mechanisms on quinolone resistance and bacterial fitness in XXXX .

@entity3284 :: ('D024841', 'Chemical') :: ['fluoroquinolone'] @entity2177 :: ('MESH:D002939', 'Chemical') :: ['ciprofloxacin'] @entity2887 :: ('MESH:D024841', 'Chemical') :: ['fluoroquinolones'] @entity2834 :: ('12305', 'Species') :: ['CMV'] @entity526 :: ('562', 'Species') :: ['Escherichia coli', 'E. coli']
@entity526 :: (562,Species) :: ['Escherichia coli']
