Description of a chromosomal fosA6 tandem multicopy fragment and its in vivo evolution in consecutive KPC-producing Klebsiella pneumoniae clinical isolates

Antimicrobial Agents and Chemotherapy 2026 Open access

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Authors: María Alejandra Mateo-Vargas, Felipe Fernández-Cuenca, Lorena López-Cerero, Manuel Rodríguez‐Iglesias, Fátima Galán‐Sánchez
DOI: 10.1128/aac.01877-25
Cited by: 1
References: 22

Abstract

ABSTRACT Chromosomal tandem duplications are scarcely reported in Klebsiella pneumoniae . We describe a chromosomal fosA6 tandem multicopy fragment present at varying copy number in five consecutive K. pneumoniae carbapenemase-producing K. pneumoniae isolates recovered from a single patient over 27 months. Fosfomycin minimum inhibitory concentrations increased with copy number; however, fosA6 expression did not scale proportionally with copy number. No other fosfomycin resistance mechanism was identified. This highlights the clinical relevance of chromosomal AMR gene amplifications.

Fields of Study & Subjects

Antibiotic Resistance in Bacteria Escherichia coli research studies Urinary Tract Infections Management

Publication details

Journal / source
Antimicrobial Agents and Chemotherapy
Publisher
American Society for Microbiology
Volume
70
Issue
6
Pages
e0187725–e0187725
Publication date
20 April 2026
Language
EN