title: High levels of dual resistance to clarithromycin and metronidazole and in vitro activity of levofloxacin against Helicobacter pylori isolates from patients after failure of therapy.
abstract: Current treatment for Helicobacter pylori infections generally includes two or more antimicrobials (amoxicillin, clarithromycin, nitroimidazoles, tetracycline, etc.), but treatment fails in 10-20% of all cases, often because of drug resistance. Levofloxacin has been proposed as an alternative for these refractory infections. We examined 67 H. pylori isolates from patients unsuccessfully treated with amoxicillin, clarithromycin, metronidazole and levofloxacin. Minimum inhibitory concentrations determined with the epsilometer test revealed clarithromycin and metronidazole resistance in 91 and 82.1% of the isolates, respectively; 52 (77.6%) were resistant to both drugs. All 67 isolates were susceptible to amoxicillin and tetracycline. Fifty-two isolates had levofloxacin MICs of 0.01-2 mg/l; the remaining 15 (22.4%), all clarithromycin- and metronidazole-resistant, had MICs >/= 8 mg/l. Levofloxacin may be an option for refractory H. pylori infections, but the choice should be based on in vitro susceptibility data, and physicians should consider local resistance patterns when treating these infections empirically.
authors.affiliation: Institute of Microbiology, Catholic University of the Sacred Hearth, Rome, Italy.
authors.forename: Giovanna
authors.initials: G
authors.lastname: Branca
authors.forename: Teresa
authors.initials: T
authors.lastname: Spanu
authors.forename: Giovanni
authors.initials: G
authors.lastname: Cammarota
authors.forename: Anna Maria
authors.initials: AM
authors.lastname: Schito
authors.forename: Antonio
authors.initials: A
authors.lastname: Gasbarrini
authors.forename: Giovanni Battista
authors.initials: GB
authors.lastname: Gasbarrini
authors.forename: Giovanni
authors.initials: G
authors.lastname: Fadda
mesh_terms: D017291:Clarithromycin / Q000008:administration & dosage / Q000494:pharmacology*; D004351:Drug Resistance; D004359:Drug Therapy, Combination; D016481:Helicobacter Infections / Q000188:drug therapy / Q000382:microbiology*; D016480:Helicobacter pylori / Q000187:drug effects* / Q000302:isolation & purification; D006801:Humans; D064704:Levofloxacin; D008795:Metronidazole / Q000494:pharmacology*; D008826:Microbial Sensitivity Tests; D009593:Nitroimidazoles / Q000008:administration & dosage; D015242:Ofloxacin / Q000494:pharmacology*; D054328:Proton Pump Inhibitors; D017211:Treatment Failure
chemical_list: D009593:Nitroimidazoles; D054328:Proton Pump Inhibitors; D008795:Metronidazole; D064704:Levofloxacin; D015242:Ofloxacin; D017291:Clarithromycin