Efflux cooperates with other mechanisms of resistance

Contributions of the AmpC b-lactamase and the AcrAB Multidrug Efflux System in Intrinsic Resistance of E. coli to b -lactams

Mazzariol et al, AAC (2000) 44:1387-1390

Efflux b-lactamase CMI carbenicillin CMI ofloxacin

- - 0.2 0.05

+ - 12.5 0.2

+++ - 50 1.56

- + 100 0.05

+ + 200 0.39

+++ + 400 1.56

WT:

intrinsic

resistance !