title: High rate of levofloxacin resistance in a background of clarithromycin- and metronidazole-resistant Helicobacter pylori in Vietnam.
abstract: Antimicrobial resistance in Helicobacter pylori has increased worldwide and has become a major cause of treatment failure in many countries, including Vietnam. It is advisable to perform an antibiogram to provide 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 and analysed point mutations in genes related to clarithromycin (CLA) and levofloxacin (LFX) resistance. A total 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<0.05). The rate of resistance to LFX was significantly higher in females than males (P<0.05). Most of the CLA- and LFX-resistant strains harboured resistance-associated mutations, with common 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 their 23S rRNA gene and in strains with Asn-87 GyrA mutation (P<0.05). One high-level LFX-resistant strain (MIC=32mg/L) had new mutations with a combination of N87A, A88N and V65I. High resistance rates to CLA, MTZ and LFX discourage standard and LFX-based triple therapies as first-line treatment in Vietnam.
authors.affiliation: Center of Gastrointestinal Endoscopy, Hue University Hospital, Huế, Viet Nam; Dipartimento di Scienze Biomediche, Università di Sassari, Sassari, Italy.
authors.forename: Trung Nam
authors.initials: TN
authors.lastname: Phan
authors.affiliation: Dipartimento di Scienze Biomediche, Università di Sassari, Sassari, Italy.
authors.forename: Antonella
authors.initials: A
authors.lastname: Santona
authors.affiliation: Center of Gastrointestinal Endoscopy, Hue University Hospital, Huế, Viet Nam.
authors.forename: Van Huy
authors.initials: VH
authors.lastname: Tran
authors.affiliation: Department of Microbiology & Carlo Urbani Center, Hue University of Medicine & Pharmacy, Huế, Viet Nam.
authors.forename: Thi Nhu Hoa
authors.initials: TN
authors.lastname: Tran
authors.affiliation: Department of Microbiology & Carlo Urbani Center, Hue University of Medicine & Pharmacy, Huế, Viet Nam.
authors.forename: Van An
authors.initials: VA
authors.lastname: Le
authors.affiliation: Dipartimento di Scienze Biomediche, Università di Sassari, Sassari, Italy; Department of Microbiology & Carlo Urbani Center, Hue University of Medicine & Pharmacy, Huế, Viet Nam.
authors.forename: Pietro
authors.initials: P
authors.lastname: Cappuccinelli
authors.affiliation: Dipartimento di Scienze Biomediche, Università di Sassari, Sassari, Italy; Department of Infection and Immunity, King Faisal Specialist Hospital and Research Center, Riyadh, Saudi Arabia.
authors.forename: Salvatore
authors.initials: S
authors.lastname: Rubino
authors.affiliation: Dipartimento di Scienze Biomediche, Università di Sassari, Sassari, Italy. Electronic address: biancap@uniss.it.
authors.forename: Bianca
authors.initials: B
authors.lastname: Paglietti
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D017291:Clarithromycin / Q000494:pharmacology*; D027081:DNA Gyrase / Q000235:genetics; D024881:Drug Resistance, Bacterial; D005260:Female; D016481:Helicobacter Infections / Q000382:microbiology; D016480:Helicobacter pylori / Q000187:drug effects* / Q000302:isolation & purification; D006801:Humans; D064704:Levofloxacin / Q000494:pharmacology*; D008297:Male; D008795:Metronidazole / Q000494:pharmacology*; D008826:Microbial Sensitivity Tests; D008875:Middle Aged; D017354:Point Mutation; D012338:RNA, Ribosomal, 23S / Q000235:genetics; D062606:Tertiary Care Centers; D014744:Vietnam; D055815:Young Adult
chemical_list: D000900:Anti-Bacterial Agents; D012338:RNA, Ribosomal, 23S; D008795:Metronidazole; D064704:Levofloxacin; D027081:DNA Gyrase; D017291:Clarithromycin
keywords: 23S rRNA gene; Helicobacter pylori; Mutations; Primary antibiotic resistance; Secondary antibiotic resistance; gyrA