Prevalence of fosfomycin resistance among ESBL-producing Escherichia coli isolates in the community, Switzerland

Abstract

Our aim was to evaluate the prevalence of fosfomycin-resistant strains among ESBL-producing Escherichia coli isolates recovered from community patients in Switzerland. A total of 1225 ESBL-producing E. coli isolates were collected between 2012 and 2013 from a private and community laboratory. Fosfomycin resistance was assessed by using the novel rapid fosfomycin/E. coli NP test and agar dilution method. Resistant isolates were further investigated for acquired resistance genes fosA1-7 by PCR and sequencing. Pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing (MLST) were performed to evaluate the clonal relationship among fosA3-carrying isolates. Out of the 1225 ESBL-producing E. coli isolates analyzed in this study, 1208 were fosfomycin susceptible while 17 were fosfomycin resistant. No discrepancy was observed between the rapid fosfomycin/ E. coli NP test and the agar dilution method taken as the gold standard. Five out of the 17 resistant isolates carried a fosA-like gene. No clonal relationship was observed among those isolates. Here, the prevalence of fosfomycin resistance among ESBLproducing E. coli isolates in the community is reported for the first time in Switzerland, being ca. 1.4%. Among the five isolates carrying a fosA gene, four encoded the FosA3 enzyme, being the most prevalent fosfomycin-resistant determinant. An excellent correlation was observed between minimum inhibitory concentration-based susceptibility categorization and results of the rapid fosfomycin/E. coli NP test, further indicating the excellent sensitivity and specificity of this recently developed rapid test whose results are obtained in less than 2 h.

High Colonization Rate and Heterogeneity of ESBL- and Carbapenemase-Producing Enterobacteriaceae Isolated from Gull Feces in Lisbon, Portugal

“…We used standard PCR conditions to amplify the β-lactamase gene bla CMY , encoding plasmid-mediated cephalosporinases [ 22 ]. Fosfomycin resistance due to a transferable glutathione- S -transferase FosA-like enzyme was searched by using the phosphonoformate test [ 23 ] after which plasmid-borne fosfomycin resistance determinants were identified by PCR followed by sequencing [ 24 , 25 ].…”

Identification of FosA8, a Plasmid-Encoded Fosfomycin Resistance Determinant from Escherichia coli, and Its Origin in Leclercia adecarboxylata

“…Bacterial strains and plasmids. E. coli isolate 376 was isolated from urine in the context of screening 1,225 ESBL-producing E. coli isolates from a Swiss collection obtained from 2012 and 2013 (20). The list of strains and plasmids used in the study is shown in Table 1.…”

“…The determination of the plasmid incompatibility group was confirmed by PCR-based replicon typing (PBRT) (30). Conjugation experiments were performed using E. coli strain 376 and azide-resistant strain E. coli J53 as donor and recipient strains, respectively, as described previously (20). Both donor and recipient strains were cultured in exponential phase and then mixed on solid Luria Broth agar using filters at a 1:10 donor/recipient ratio.…”

“…Recently, by performing a screening of fosfomycin resistance determinants among a collection of ESBL-producing E. coli isolates from Switzerland, we identified a single isolate harboring a plasmid-mediated fosfomycin resistance determinant that did not correspond to any known fosA gene (20). Therefore, the purpose of the study was to characterize this fosfomycin resistant determinant and to identify its origin.…”

Characterization of FosL1, a Plasmid-Encoded Fosfomycin Resistance Protein Identified in Escherichia coli

“…We recently performed a screening of fosfomycin resistance among a collection of ESBL-producing E. coli from Switzerland recovered in 2012 (17). Hence, we identified a fosfomycin-resistant isolate harboring a novel fos gene coding for a putative glutathione S-transferase located on a conjugative plasmid.…”