Carbapenemase-producing Enterobacteriaceae (CPE) isolated from pigs in China

Background The increasing prevalence of CPE is a global concern in public health. CPE were found to be present in livestock. Food animals act as a reservoir for NDM-producing bacteria. However, there is limited information about CPE in food animals. Here we screen the carbapenemase-producing bacteria in pig samples. Objective To investigate the prevalence of carbapenem resistance in swine from China. Methods A total of 138 rectal swabs from pigs imported from China were collected in Hong Kong between June 2017 and Oct 2018. Bacterial identification was conducted by MALDI-TOF for all isolates. Carba-NP test and disc diffusion method were performed to detect carbapenemase and determine the antibiotic susceptibility. Identification of carbapenemase gene and replicon type of plasmid, and further characterization of isolates were performed through PCR and next-generation sequencing respectively. Results Twenty-one CPE isolates including Escherichia coli (n=20) and Enterobacter cloacae (n=1) were isolated from 20 pigs, which were resistant to carbapenem (meropenem, ertapenem and imipenem). The prevalence rate of carbapenemase producers was 14 % (20/138). All isolates were positive in carba-NP test and harboured carbapenemase gene bla NDM. Two-third of IncX3 (14/21) plasmid appeared in bla NDM-producing isolates. Different resistance patterns were discovered among NDM-carrying isolates, but all of them were susceptible to fosfomycin and azithromycin. Conclusion Our data show that the prevalence of carbapenem-resistance Enterobacteriaceae among swine in China during 2017 to 2018 . It is also observed that NDM carbapenemases is still circulating in pigs over times.