High rate of levofloxacin resistance in a background of clarithromycin-and metronidazole-resistant <i>Helicobacter pylori</i> in Vietnam

Abstract

Antimicrobial resistance in Helicobacter pylori has increased worldwide and has become a major causeof treatment failure in many countries, including Vietnam. It is advisable to perform an antibiogram toprovide optimal regimens for H. pylori eradication. This study evaluated the rate of antibiotic resistance to the four commonly used antibiotics against H. pylori at a tertiary care hospital in Central Vietnam andanalysed point mutations in genes related to clarithromycin (CLA) and levofloxacin (LFX) resistance. Atotal of 92 H. pylori strains from gastric biopsy specimens were tested; 42.4% were resistant to CLA (primary, 34.2%; secondary, 73.7%), 41.3% to LFX (primary, 35.6%; secondary, 63.2%), 76.1% to metronidazole(MTZ) and 1.1% to amoxicillin. Multidrug resistance was observed in 56.5% (primary, 50.7%; secondary,78.9%) of isolates (P &lt; 0.05). The rate of resistance to LFX was significantly higher in females than males(P &lt; 0.05). Most of the CLA- and LFX-resistant strains harboured resistance-associated mutations, withcommon positions at A2143G and T2182C in the 23S rRNA gene and at Asn-87 or Asp-91 in GyrA. Minimum inhibitory concentrations (MICs) increased in strains carrying quadruple mutations in their23S rRNA gene and in strains with Asn-87 GyrA mutation (P &lt; 0.05). One high-level LFX-resistant strain(MIC = 32 mg/L) had new mutations with a combination of N87A, A88N and V65I. High resistance rates toCLA, MTZ and LFX discourage standard and LFX-based triple therapies as first-line treatment in Vietnam