ESBL-producing strains isolated from imported cases of enteric fever in England and Wales reveal multiple chromosomal integrations of blaCTX-M-15in XDR Salmonella Typhi

Satheesh Nair, Marie Anne Chattaway, Gemma C. Langridge, Amy Gentle, Martin Day, Emma V. Ainsworth, Iman Mohamed, Robert Smith, Claire Jenkins, Tim Dallman, Gauri Godbole

Research output: Contribution to journalArticlepeer-review

4 Citations (Scopus)

Abstract

BACKGROUND: There are approximately 300 cases of enteric fever reported annually from England and Wales; most are imported infections. Clinical management of enteric fever remains a challenge with the emergence of ESBL-producing strains, especially XDR Salmonella Typhi from Sindh, Pakistan. 

METHODS: All strains of S. Typhi and Salmonella Paratyphi A isolated from cases presenting with symptoms of enteric fever in England and Wales, between 1 April 2014 and 31 March 2020, were characterized using WGS. Antibiotic susceptibility testing was performed using an agar dilution method. 

RESULTS: ESBL strains contributed to 69 cases of enteric fever (S. Typhi n = 68, S. Paratyphi A n = 1); 68 were imported (Pakistan n = 64, Iraq n = 2, Bangladesh n = 1 and India n = 1). Ages ranged from 1 to 56 years, 36/69 (52%) were children, 52% were female and the duration of hospital stay ranged from 1 to 23 days. The ESBL phenotype was conferred by the presence of blaCTX-M-15 (S. Typhi n = 67 and S. Paratyphi A n = 1) or blaCTX-M-55 (S. Typhi n = 1). An IncY plasmid harbouring blaCTX-M-15 and qnr was detected in 56 strains from Pakistan. The IncY plasmid was absent in the remaining strains and there was evidence of a 4 kb ISEcpl-blaCTX-M-15-tnp gene cassette insertion into the chromosome at one of three integration points. 

CONCLUSIONS: Chromosomal integration of blaCTX-M-15 within the XDR Sindh strains may lead to the maintenance of resistance in the absence of antibiotic selection pressure. Empirical treatment of cases of complicated enteric fever returning from Pakistan will henceforth have to include a carbapenem.

Original languageEnglish
Pages (from-to)1459-1466
Number of pages8
JournalJournal of Antimicrobial Chemotherapy
Volume76
Issue number6
Early online date10 Mar 2021
DOIs
Publication statusPublished - 1 Jun 2021

Bibliographical note

Publisher Copyright:
© 2021 The Author(s). Published by Oxford University Press on behalf of the British Society for Antimicrobial Chemotherapy. All rights reserved.

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