Molecular Epidemiology of Fosfomycin Resistant E. coli from a Pigeon Farm in China

Abstract

We determined the prevalence and molecular characteristics of fosfomycin-resistant <i>Escherichia coli</i> from a domestic pigeon farm. A total of 79 samples collected from pigeons and their surrounding environments were screened for the presence of fosfomycin resistant isolates and these included 49 <i>E. coli</i> isolates that displayed high-level resistance (MIC ≥ 256 mg L^-1) and carried the <i>fosA3</i> gene on plasmids with sizes ranging from 80 to 370 kb. MLST analysis of these <i>fosA3</i>-positive <i>E. coli</i> isolates indicated the presence of nine sequence types (ST6856, ST8804, ST457, ST746, ST533, ST165, ST2614, ST362 and ST8805) of which ST6856 was the most prevalent (24.5%, 12/49). PFGE combined with genomic context comparative analyses indicated that the <i>fosA3</i> gene was spread by horizontal transfer as well as via clonal transmission between <i>E. coli</i> in the pigeon farm, and IS<i>26</i> played an important role in <i>fosA3</i> transmission. The high prevalence of <i>fosA3</i> in the pigeon farm and the high similarity of the <i>fosA3</i> genomic environment between <i>E. coli</i> isolates from humans and pigeons indicated that the pigeon farm served as a potential reservoir for human infections. The pigeon farm was found to be an important reservoir for the <i>fosA3</i> gene and this should be further monitored.