RESUMO
Fosfomycin is gaining renewed interest for treating urinary tract infections. Monitoring fosfomycin resistance is therefore important in order to detect the emergence of novel resistance mechanisms. Here, we used the Rapid Fosfomycin NP test to screen a collection of extended-spectrum-ß-lactamase-producing Escherichia coli isolates from Switzerland and found a fosfomycin-resistant isolate in which a novel plasmid-mediated fosfomycin resistance gene, named fosL1, was identified. The FosL1 protein is a putative glutathione S-transferase enzyme conferring high-level resistance to fosfomycin and sharing between 57% to 63% amino acid identity with other FosA-like family members. Genetic analyses showed that the fosL1 gene was embedded in a mobile insertion cassette and had likely been acquired by transposition through a Tn7-related mechanism. In silico analysis over GenBank databases identified the FosL1-encoding gene in addition to another variant (fosL1 and fosL2, respectively) in two Salmonella enterica isolates from the United States. Our study further highlights the necessity of monitoring fosfomycin resistance in Enterobacteriaceae to identify the emergence of novel mechanisms of resistance.
Assuntos
Antibacterianos/farmacologia , Farmacorresistência Bacteriana/genética , Escherichia coli/efeitos dos fármacos , Escherichia coli/genética , Fosfomicina/farmacologia , Proteínas Proto-Oncogênicas c-fos/genética , Elementos de DNA Transponíveis/genética , Escherichia coli/isolamento & purificação , Humanos , Testes de Sensibilidade Microbiana , Plasmídeos/genética , Salmonella enterica/efeitos dos fármacos , Salmonella enterica/genética , Salmonella enterica/isolamento & purificação , Suíça , beta-Lactamases/genética , beta-Lactamases/metabolismoRESUMO
A plasmid-located fosfomycin resistance gene, fosA8, was identified from a CTX-M-15-producing Escherichia coli isolate recovered from urine. Identification of this gene was obtained by whole-genome sequencing. It encoded FosA8, which shares 79% and 78% amino acid identity with the most closely related FosA2 and FosA1 enzymes, respectively. The fosA8 gene was located on a transferable 50-kb plasmid of IncN type encoding high-level resistance to fosfomycin. In silico analysis and cloning experiments identified fosA8 analogues (99% identity) in the genome of Leclercia decarboxylata, which is an enterobacterial species with natural resistance to fosfomycin. This finding adds L. decarboxylata to the list of enterobacterial species that are a reservoir of fosA-like genes which have been captured from the chromosome of a progenitor and are then acquired by E. coli.
Assuntos
Antibacterianos/farmacologia , Enterobacteriaceae/genética , Proteínas de Escherichia coli/genética , Escherichia coli/efeitos dos fármacos , Fosfomicina/farmacologia , Genes Bacterianos/genética , Plasmídeos/genética , Clonagem Molecular , Farmacorresistência Bacteriana/genética , Enterobacteriaceae/efeitos dos fármacos , Escherichia coli/genética , Filogenia , Sequenciamento Completo do GenomaRESUMO
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 ESBL-producing 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.
Assuntos
Antibacterianos/farmacologia , Farmacorresistência Bacteriana Múltipla , Infecções por Escherichia coli/microbiologia , Escherichia coli/efeitos dos fármacos , Escherichia coli/enzimologia , Fosfomicina/farmacologia , beta-Lactamases/biossíntese , DNA Bacteriano/genética , Farmacorresistência Bacteriana Múltipla/genética , Escherichia coli/classificação , Escherichia coli/genética , Infecções por Escherichia coli/epidemiologia , Proteínas de Escherichia coli/genética , Humanos , Testes de Sensibilidade Microbiana , Tipagem Molecular , Prevalência , Análise de Sequência de DNA , Suíça/epidemiologia , beta-Lactamases/genéticaRESUMO
Among 10 strains of community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) isolated in 2002 from patients with skin infections, seven harbored the Panton-Valentine leukocidin gene, two harbored the exfoliative toxin A gene, and one harbored neither of these genes. CA-MRSA isolates producing a variety of exotoxins are currently spreading in the Swiss community.
