G Model ANTAGE-4301; No. of Pages 2

ARTICLE IN PRESS International Journal of Antimicrobial Agents xxx (2014) xxx–xxx

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International Journal of Antimicrobial Agents journal homepage: http://www.elsevier.com/locate/ijantimicag

Letter to the Editor Helicobacter pylori resistance to ciprofloxacin in Iran Sir, Triple therapy regimens for Helicobacter pylori eradication have recently shown unsatisfactory efficacy in many countries. Primary therapy is usually successful in 60–85% of patients. Antibiotic resistance of H. pylori is the main cause of treatment failure, which varies extensively by geographic region and between patients within a region. Thus, alternative treatment regimens may include a combination of bismuth compound, metronidazole, tetracycline, fluoroquinolones and rifamycin derivatives. Fluoroquinolones are not usually used for primary eradication of H. pylori but may be used in alternative treatment regimens when other antibiotics fail [1]. As resistance to fluoroquinolones may be acquired rapidly, this class of antibiotic should be used with caution in the treatment of H. pylori. The aim of this study was to determine the ciprofloxacin resistance pattern of H. pylori strains isolated from H. pylori-infected patients in Kashan (Iran). A total of 95 H. pylori strains were isolated from the gastric mucosa of 246 patients undergoing gastroscopy with different clinical signs in Kashan in 2013. Minimum inhibitory concentrations (MICs) of ciprofloxacin in H. pylori were determined by Etest (Liofilchem, Roseto degli Abruzzi, Italy). The occurrence of mutations in gyrA of ciprofloxacin-resistant strains was investigated. To identify mutations related to ciprofloxacin resistance in the gyrA gene, PCR amplification was performed with oligonucleotide primers derived from a known sequence of the gyrA gene with 582 bp length. Genomic DNA was extracted using a QIAamp Kit (QIAGEN, Courtaboeuf, France). Sequencing was done by the Sanger method using an Applied Biosystems 3730/3730xl DNA Analyzer (Bioneer, Daejeon, South Korea). Sequences were analysed using ChromasPro v.1.7.5 (http://www.technelysium.com.au). The quinolone resistance-determining region (QRDR) of gyrA was sequenced using primers for gyrA in ciprofloxacin-resistant strains and was compared with the sequences from ciprofloxacinsensitive isolates. Antibiotic susceptibility testing showed that 65.3% of isolated H. pylori strains (62/95) were resistant to ciprofloxacin (MICs ≥ 1 ␮g/mL). In addition, ca. 41.9% of ciprofloxacin-resistant strains (26/62) showed high-level resistance (MIC ≥ 32 ␮g/mL) (Fig. 1). In the present study, among the ciprofloxacin-resistant strains, isolates with a MIC ≥ 16 ␮g/mL harboured a specific mutation in the QRDR of the gyrA gene that was previously reported to confer resistance to fluoroquinolones. The concerned amino acid positions were 87 and 91. It has been reported that H. pylori resistance to fluoroquinolones is induced by mutations in the GyrA protein located in the QRDR, which is the target of fluoroquinolones, leading to inhibition of DNA

replication. In ciprofloxacin-resistant H. pylori isolates, several types of base substitutions were associated with increased MICs of ciprofloxacin from

Helicobacter pylori resistance to ciprofloxacin in Iran.

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