Detection of optrA and poxtA genes in linezolid-resistant Enterococcus isolates from fur animals in China

The emergence of linezolid-resistant (LR) enterococci found in food of animal origin arouses attention, but little is known about LR enterococci in fur animals. A total of 342 Enterococcus faecalis and 265 E. faecium strains isolated from fur animals in China from 2015 to 2017 were investigated to determine if LR enterococci (≥16 μg ml-1 ) are present. Overall, two E. faecalis and 12 E. faecium among these isolates were resistant to linezolid. In addition, all LR isolates were classified as multidrug-resistant isolates. We further explore the resistance genes of the LR enterococci, four E. faecalis and two E. faecium isolates contained optrA gene. Two of them co-harboured optrA and poxtA genes. We detected virulence genes in LR enterococci were the following: asa1, cylA, esp, gelE and hyl, among which the highest carrying rate gene was asa1. Besides, all of the LR enterococci we tested had the biofilm-forming ability. It is worth noting that we detected a novel ST type ST2010 from E. faecium 82-2. These data show LR enterococci exist in fur animals and have unique characteristics.