Most E. coli isolates (73.7%) expressed both the OmpC (38–40 kDa) and OmpF (36 kDa) proteins identical to that of the fluoroquinolone-susceptible control strain, E. coli HB 101 (Table 1). Two isolates (F17 and F20) showed OmpF expression with decreased OmpC expression. Five isolates expressed the OmpC protein only. Only isolates F9 and F18 expressed rough (R) LPS profiles, while the remainder displayed the smooth (S) LPS phenotype.