PORIN ALTERATION AND ACTIVE EFFLUX - 2 IN-VIVO DRUG-RESISTANCE STRATEGIES USED BY ENTEROBACTER-AEROGENES

Enterobacter aerogenes is among the five most frequently isolated noso comial pathogens in France. and this bacterium also shows increasing m ultidrug resistance. In this study, various E. aerogenes strains isola ted from hospital units were characterized for their outer-membrane pr oteins, antibiotic susceptibilities (inhibition diameters and MICs) an d resistance mechanisms associated with modification of envelope perme ability (porin alteration and active efflux). Diminished outer-membran e permeability due to porin alterations was found in conjunction with the expression of an enzymic barrier in resistant isolates. Interestin gly. changes in the functional expression of porins appeared to play a special role in susceptibility to cefepime. An active efflux to quino lones was also identified. Simultaneous changes in envelope permeabili ty, i.e. a porin deficiency (in) and an efflux mechanism (out), were c learly evident in two clinical strains.