OMP profiles of selected E. coli isolates and control strains grown in nutrient broth. Proteins were separated on 10% polyacrylamide-8 M urea gels and stained with Coomassie blue. (A) Comparison of isolates with phenotypes designated as A (EC3589, EC3437, EC922, and EC3095) or B (EC689, EC3194, EC3076) and control strains E. coli C600 (wild type), E. coli MH225 (OmpC−), and CDC3100 (enhanced AmpC producer). (B) Comparison of isolates with phenotypes designated as C (EC251), D (EC4081), A (EC3006), or E (EC1552) and E. coli C600 and E. coli MH225 (OmpC−).