Aurélie Cointe1,2, André Birgy1,2, Antoine Bridier-Nahmias1, Patricia Mariani-Kurkdjian1,2, Violaine Walewski1,3, Corinne Lévy4,5, Robert Cohen4,5,6, Patrick Fach7, Sabine Delannoy7, Philippe Bidet1,2, Stéphane Bonacorsi1,2. 1. Université de Paris, IAME, INSERM, F-75018 Paris, France. 2. Service de Microbiologie, Centre National de Référence Escherichia coli, Hôpital Robert-Debré, AP-HP, Paris, France. 3. Service de Microbiologie, Hôpital Avicenne, AP-HP, Paris, France. 4. ACTIV, Association Clinique et Thérapeutique Infantile du Val-de-Marne, Saint Maur-des-Fossés, France. 5. Université Paris Est, IMRB-GRC GEMINI, Clinical Research Center (CRC), Centre Hospitalier Intercommunal de Créteil, Créteil, France. 6. Unité Court Séjour, Petits Nourrissons, Service de Néonatalogie, Centre Hospitalier Intercommunal de Créteil, Créteil, France. 7. ANSES, Plateforme IdentyPath, Maisons-Alfort, France.
Abstract
OBJECTIVES: Enterohaemorrhagic Escherichia coli (EHEC) infections may be complicated by haemolytic uraemic syndrome (HUS). The emerging worldwide EHEC serogroup O80 has acquired a mosaic plasmid combining extraintestinal virulence and antibiotic resistance. This hybrid pathotype is associated with invasive infections that require antibiotic therapy, classically not recommended in EHEC infections, increasing the risk of HUS. We characterized two ESBL-producing O80 EHEC strains, which is an unusual resistance mechanism among EHECs, and determined the safest therapy to be used for invasive infections. METHODS: WGS of two strains isolated from the stools of an asymptomatic carrier and a patient with HUS was performed using Illumina and Nanopore technologies. Generated reads were combined to assemble genomes. We determined the safest therapy by comparing Shiga toxin (Stx) production by the two strains in the presence of several antibiotics. RESULTS: The strains were genetically close to the O80 EHEC clone, belonging to ST301 and harbouring stx2d, eae-ξ, ehxA and genes characteristic of the extraintestinal virulence plasmid pS88. Long-read sequencing identified the acquisition of an additional plasmid harbouring CTX-M-type genes (blaCTX-M-14 and blaCTX-M-1). Azithromycin decreased Stx production at subinhibitory concentrations, ciprofloxacin increased it and imipenem had no major effect. The combination of azithromycin and imipenem overall reduced Stx production. CONCLUSIONS: Acquisition of an additional plasmid harbouring ESBL genes is a step towards increasing the risk of O80 EHEC dissemination and represents a serious public health concern. The combination of azithromycin and imipenem reduced Stx production and suggests that this combination could be tested in clinical trials.
OBJECTIVES: Enterohaemorrhagic Escherichia coli (EHEC) infections may be complicated by haemolytic uraemic syndrome (HUS). The emerging worldwide EHEC serogroup O80 has acquired a mosaic plasmid combining extraintestinal virulence and antibiotic resistance. This hybrid pathotype is associated with invasive infections that require antibiotic therapy, classically not recommended in EHEC infections, increasing the risk of HUS. We characterized two ESBL-producing O80 EHEC strains, which is an unusual resistance mechanism among EHECs, and determined the safest therapy to be used for invasive infections. METHODS: WGS of two strains isolated from the stools of an asymptomatic carrier and a patient with HUS was performed using Illumina and Nanopore technologies. Generated reads were combined to assemble genomes. We determined the safest therapy by comparing Shiga toxin (Stx) production by the two strains in the presence of several antibiotics. RESULTS: The strains were genetically close to the O80 EHEC clone, belonging to ST301 and harbouring stx2d, eae-ξ, ehxA and genes characteristic of the extraintestinal virulence plasmid pS88. Long-read sequencing identified the acquisition of an additional plasmid harbouring CTX-M-type genes (blaCTX-M-14 and blaCTX-M-1). Azithromycin decreased Stx production at subinhibitory concentrations, ciprofloxacin increased it and imipenem had no major effect. The combination of azithromycin and imipenem overall reduced Stx production. CONCLUSIONS: Acquisition of an additional plasmid harbouring ESBL genes is a step towards increasing the risk of O80 EHEC dissemination and represents a serious public health concern. The combination of azithromycin and imipenem reduced Stx production and suggests that this combination could be tested in clinical trials.
Authors: Dafne Díaz-Jiménez; Isidro García-Meniño; Alexandra Herrera; Vanesa García; Ana María López-Beceiro; María Pilar Alonso; Jorge Blanco; Azucena Mora Journal: Antibiotics (Basel) Date: 2020-04-17