Characterization of Fosfomycin and Nitrofurantoin Resistance Mechanisms in Escherichia coli Isolated in Clinical Urine Samples

Abstract

Fosfomycin and nitrofurantoin are antibiotics of choice to orally treat non-complicated urinary tract infections (UTIs) of community origin because they remain active against bacteria resistant to other antibiotics. However, epidemiologic surveillance studies have detected a reduced susceptibility to these drugs. The objective of this study was to determine possible mechanisms of resistance to these antibiotics in clinical isolates of fosfomycin- and/or nitrofurantoin-resistant UTI-producing Escherichia coli. We amplified and sequenced murA, glpT, uhpT, uhpA, ptsI, cyaA, nfsA, nfsB, and ribE genes, and screened plasmid-borne fosfomycin-resistance genes fosA3, fosA4, fosA5, fosA6, and fosC2 and nitrofurantoin-resistance genes oqxA and oqxB by polymerase chain reaction. Among 29 isolates studied, 22 were resistant to fosfomycin due to deletion of uhpT and/or uhpA genes, and 2 also possessed the fosA3 gene. Some modifications detected in sequences of NfsA (His11Tyr, Ser33Arg, Gln67Leu, Cys80Arg, Gly126Arg, Gly154Glu, Arg203Cys), NfsB (Gln44His, Phe84Ser, Arg107Cys, Gly192Ser, Arg207His), and RibE (Pro55His), and the production of truncated NfsA (Gln67 and Gln147) and NfsB (Glu54), were associated with nitrofurantoin resistance in 15/29 isolates; however, the presence of oqxAB plasmid genes was not detected in any isolate. Resistance to fosfomycin was associated with the absence of transporter UhpT expression and/or the presence of antibiotic-modifying enzymes encoded by fosA3 plasmid-mediated gene. Resistance to nitrofurantoin was associated with modifications of NfsA, NfsB, and RibE proteins. The emergence and spread of these resistance mechanisms, including transferable resistance, could compromise the future usefulness of fosfomycin and nitrofurantoin against UTIs. Furthermore, knowledge of the genetic mechanisms underlying resistance may lead to rapid DNA-based testing for resistance.

Occurrence and molecular epidemiology of fosA3-bearing Escherichia coli from ducks in Shandong province of China

“…fosA3 is the most prevalent plasmid-mediated fosfomycin resistance gene ( Yang et al, 2019 ). Presently, fosA3 is widely distributed among E. coli strains isolated from Asian countries, the United States, and Europe ( Wachino et al, 2010 ; Hou et al, 2012 ; Lee et al, 2012 ; Alrowais et al, 2015 ; Benzerara et al, 2017 ; Wang et al, 2017 ; Sorlozano-Puerto et al, 2020 ). Therefore, the possible global dissemination of fosA3 -bearing E. coli isolates has become a serious public health concern ( Zurfluh et al, 2020 ).…”

Inhibition of MurA Enzyme from Escherichia coli and Staphylococcus aureus by Diterpenes from Lepechinia meyenii and Their Synthetic Analogs

“…The naturally occurring broad-spectrum antibiotic, fosfomycin, which acts as an analogue of PEP by covalently reacting with the active site Cys residue of MurA [ 9 , 12 ], is the unique inhibitor of this enzyme approved for clinical use [ 8 ]. However, resistance to fosfomycin, a phenomenon caused by various mechanisms, including the overexpression or mutations of MurA, leads to less effective therapies [ 8 , 13 , 14 ]. This scenario drives efforts to identify novel chemical scaffolds with inhibitory properties on Mur enzymes.…”

Synergistic Effect of Propolis and Antibiotics on Uropathogenic Escherichia coli

“…It is noteworthy that synergistic activity was observed when propolis was combined with CRO, OFX and ETP, but we did not observe a same trend concerning the combination with FOS, the first antibiotic of choice to treat the non-complicated UTIs of community origin [31,32]. However, the resistance to this antibiotic was particularly low [33], notably among ESBL-producing uropathogenic enterobacteria [34], suggesting that the absence of activity of propolis was less important in this situation.…”