Molecular epidemiology and mechanisms of fosfomycin-resistant Escherichia coli producing extended-spectrum β-lactamases isolated from urine / 临床检验杂志

ABSTRACT

Objective@#To investigate the molecular epidemiology and mechanisms of fosfomycin-resistant Escherichia coli isolates producing extended-spectrum β-lactamases (ESBLs) isolated from urine. @*Methods@#Fosfomycin-resistant phenotypes were screened by drug susceptibility test in ESBLs-producing E.coli stains. The ESBLs gene and fosfomycin resistant gene were amplified by PCR. The molecular typing was analyzed by multiple sequence type (MLST). The transferability of the drug resistant gene was verified by conjugation assays. @*Results@#Among the 308 strains of E.coli isolated from urine, there were 168 (54.54%) ESBLs producing strains and 18 (10.71%, 18/168) fosfomycin resistant strains. In the drug resistant genes, the incidence of bla SHV was about 88.9% (16/18), bla CTX-M was 77.8% (14/18), bla TEM-208 was 5.6% (1/18), bla TEM-1b was 61.1% (11/18) and fosA3 was 83.3% (15/18). The main MLST genotype was ST131. The conjugation test confirmed the transferability of resistance in fosA3 positive strain. @*Conclusion@#The fosfomycin resistant rate of ESBLs producing E.coli in urethral infection was in a low level. The fosA3 gene was the main mechanism of fosomycin resistance and located on the conjugation plasmids, which should be the main node of horizontal gene transmission. We need to pay great attention to this resistant gene.