The loss of OmpC or OmpF observed in some isolates has been described previously in fluoroquinolone-resistant E. coli isolates. 2,5 Decreased expression or absence of OmpF has been implicated in increased permeability of the cell envelope to hydrophilic agents, including ciprofloxacin. Fluoroquinolone exposure is not always implicated in LPS alteration of resistant E. coli isolates. 12 This was also evident in the present study where 17/19 isolates showed no significant LPS alterations (Table 1).