Prevalence of fosfomycin resistance and plasmid-mediated fosfomycin-modifying enzymes among carbapenem-resistant Enterobacteriaceae in Zhejiang, China

Two hundred and thirty-three nonduplicated clinical isolates of carbapenem-resistant Enterobacteriaceae were collected from four hospitals in Zhejiang, China. 45.1 % (105/233) strains were resistant to fosfomycin, among which plasmid-mediated fosfomycin-modifying enzymes fosA, fosA2, fosA3 and fosA5 were positive, and the other fos genes were negative. 80 % (12/15) Enterobacter cloacae isolates were positive for fosA. 100 % (73/73) Klebsiella pneumoniae isolates were positive for fosA5. A conjugation experiment indicated that fosfomycin resistance could be transferred to an Escherichia coli recipient strain successfully. Fosfomycin still exhibits partial activity in carbapenem-resistant Enterobacteriaceae, especially carbapenem-resistant Escherichia coli. To our knowledge, plasmid-mediated fosfomycin-modifying enzymes account for the dominance in the carbapenem-resistant Enterobacteriaceae. Therefore, we need to pay attention to the plasmid-mediated fosfomycin-modifying enzymes fosA and fosA5 in Enterobacter cloacae and K. pneumoniae to prevent clonal dissemination in China.