In vitro activity of levofloxacin against Helicobacter pylori isolates from patients after treatment failure.

We tested the in vitro activity of levofloxacin (LEV), amoxicillin (AMP), clarithromycin (CLA), metronidazole (MET), and tetracycline (TET) against 70 clinical isolates of Helicobacter pylori recovered from 70 dyspeptic patients. All patients had previously failed 2 treatment regimens: first-line triple therapy with omeprazole, AMP, and CLA, and second-line quadruple therapy with omeprazole, MET, TET, and bismuth. Resistance to CLA, MET, and LEV was found in 65.7%, 57.1%, and 18.6% of isolates, respectively. Resistance to both CLA and MET was found in 32.8%, and to CLA, MET, and LEV in 12.8%. Only 4 of the isolates were resistant to both CLA and LEV, and none was resistant to LEV alone or to MET and LEV. Physicians should consider triple therapy with omeprazole, LEV, and AMP in patients unsuccessfully treated with first- and second-line regimens.