Constantin Hays1, Christophe Burucoa2, Philippe Lehours3,4, Cong Tri Tran2, Anaïs Leleu1, Josette Raymond1. 1. Bacteriology, University of Paris-Descartes, Cochin Hospital, Paris, France. 2. EA 4331 LITEC, Université de Poitiers, Laboratoire de bactériologie, Hygiène, CHU de Poitiers, Poitiers, France. 3. INSERM UMR1053, Bordeaux Research in Translational Oncology, BaRITOn, Université de Bordeaux, Bordeaux, France. 4. French National Reference Centre for Campylobacters and Helicobacter, Bordeaux Hospital, Bordeaux, France.
Abstract
INTRODUCTION: Antibiotic resistance is a major contributing factor in treatment failure of Helicobacter pylori eradication. Rifabutin (RB) is a rescue treatment and rifampicin (RP) is used to screen RB resistance in vitro. The aim of this study was to evaluate the rate of rifamycins resistance and to determine the mutations in the rpoB gene conferring resistance to discuss the current break point. METHODS: Antimicrobial susceptibility to RP was first determined by E-test for 1015 H. pylori isolates. RP and RB MICs were then determined by agar dilution method for strains with MIC of RP > 1 mg/L, and the rpoB gene was sequenced. RESULTS: Overall, 54 of 1015 strains exhibited a RP MIC > 1 mg/L by agar dilution method. Among these 54 strains, 10 had MICs of RP > 4 mg/L and RB ≥ 1 mg/L. They all carried at least one mutation in the rpoB gene at codons 530, 538, 540, 525 in the RP resistance-determining region (RRDR). Implication of the mutation L547F was confirmed by site-directed mutagenesis experiment. In contrast, among the 44 H. pylori isolates with a MIC of RP comprised between 2 and 4 mg/L, only 4 of 44 (9%) strains exhibited a mutation in rpoB, but outside RRDR (codons 470, 499, 636, or 657). For 31 of 44 tested strains, the RB MICs were ≤0.064 mg/L. CONCLUSION: These results suggest that H. pylori isolates should be classified as resistant to RP for MICs > 4 mg/L. We considered that the optimal cut off for RB was ≥0.125 mg/L. We report a new mutation responsible for rifamycins, resistance, L547F.
INTRODUCTION: Antibiotic resistance is a major contributing factor in treatment failure of Helicobacter pylori eradication. Rifabutin (RB) is a rescue treatment and rifampicin (RP) is used to screen RB resistance in vitro. The aim of this study was to evaluate the rate of rifamycins resistance and to determine the mutations in the rpoB gene conferring resistance to discuss the current break point. METHODS: Antimicrobial susceptibility to RP was first determined by E-test for 1015 H. pylori isolates. RP and RB MICs were then determined by agar dilution method for strains with MIC of RP > 1 mg/L, and the rpoB gene was sequenced. RESULTS: Overall, 54 of 1015 strains exhibited a RP MIC > 1 mg/L by agar dilution method. Among these 54 strains, 10 had MICs of RP > 4 mg/L and RB ≥ 1 mg/L. They all carried at least one mutation in the rpoB gene at codons 530, 538, 540, 525 in the RP resistance-determining region (RRDR). Implication of the mutation L547F was confirmed by site-directed mutagenesis experiment. In contrast, among the 44 H. pylori isolates with a MIC of RP comprised between 2 and 4 mg/L, only 4 of 44 (9%) strains exhibited a mutation in rpoB, but outside RRDR (codons 470, 499, 636, or 657). For 31 of 44 tested strains, the RB MICs were ≤0.064 mg/L. CONCLUSION: These results suggest that H. pylori isolates should be classified as resistant to RP for MICs > 4 mg/L. We considered that the optimal cut off for RB was ≥0.125 mg/L. We report a new mutation responsible for rifamycins, resistance, L547F.
Authors: William R Jacobs; Wendy A Szymczak; Rajagopalan Saranathan; Michael H Levi; Alice R Wattam; Adel Malek; Emmanuel Asare; Daniel S Behin; Debra H Pan Journal: J Clin Microbiol Date: 2020-02-24 Impact factor: 5.948
Authors: Muhammad Miftahussurur; Modesto Cruz; Dalla Doohan; Phawinee Subsomwong; José A Jiménez Abreu; Celso Hosking; Langgeng Agung Waskito; Yoshio Yamaoka Journal: PLoS One Date: 2019-03-27 Impact factor: 3.240
Authors: Davide Giuseppe Ribaldone; Sharmila Fagoonee; Marco Astegiano; Marilena Durazzo; Anna Morgando; Tatiana Sprujevnik; Chiara Giordanino; Monica Baronio; Claudio De Angelis; Giorgio Maria Saracco; Rinaldo Pellicano Journal: J Clin Med Date: 2019-02-06 Impact factor: 4.241