Loras, CristinaGonzález-Prieto, AndreaPerez-Vazquez, MariaBautista, VeronicaÁvila, AliciaSola-Campoy, Pedro JuanOteo-Iglesias, JesusAlós, Juan-Ignacio2021-05-172021-05-172021-03-21J Glob Antimicrob Resist . 2021 Mar 21;25:137-141.http://hdl.handle.net/20.500.12105/12965The aim of this this study was to describe the presence of different variants of the fosA gene in fosfomycin-resistant Escherichia coli strains in Madrid, Spain. fos genes were searched for in 55 E. coli strains collected from seven representative hospitals located in Madrid. A phenotypic screening test was performed following the disk diffusion method with sodium phosphonoformate added as described by Nakamura et al. Additionally, a molecular study based on PCR was used to confirm the screening results. Positive strains for fos genes were further subjected to whole-genome sequencing (WGS). Phenotypic screening was positive in 9/55 strains (16.4%), although genotypic detection was positive in only 3 (fosA3, fosA4 and fosA6). Thus, the prevalence of fos genes in Madrid was 5.5% (3/55). WGS data were not available for the fosA6-positive strain. One isolate with fosA3 (ST69) carried a blaCTX-M-55 gene and seven virulence genes (air, eilA, iha, iss, lpfA, sat and senB). The fosA4-positive isolate (ST4038) carried the virulence genes iss, lpfA, iroN and mchF. Both fos genes were located between two IS26 mobile elements of a plasmid. We detected the presence of different variants of plasmid-mediated fosA genes in fosfomycin-resistant E. coli strains in Madrid, Spain. Despite the few reports in Europe, it would be of interest to monitor the spread of these acquired resistance genes.engVoRhttp://creativecommons.org/licenses/by-nc-nd/4.0/Antibiotic resistanceEscherichia coliFosfomycinUrinary tract infectionfosAAttribution-NonCommercial-NoDerivatives 4.0 Internacional3375782025137-14110.1016/j.jgar.2021.02.0322213-7173Journal of Global Antimicrobial Resistanceopen access