Increased prevalence of strains from food carrying and -bearing plasmids that structurally resemble those of clinical strains, China, 2015 to 2017.

IntroductionEmergence of resistance determinants of and has undermined the antimicrobial effectiveness of the last line drugs carbapenems and colistin.AimThis work aimed to assess the prevalence of and in strains collected from food in Shenzhen, China, during the period 2015 to 2017.MethodsMultidrug-resistant strains were isolated from food samples. Plasmids encoding or genes were characterised and compared with plasmids found in clinical isolates.ResultsAmong 1,166 non-repeated cephalosporin-resistant strains isolated from 2,147 food samples, 390 and 42, respectively, were resistant to colistin and meropenem, with five strains being resistant to both agents. The rate of resistance to colistin increased significantly (p < 0.01) from 26% in 2015 to 46% in 2017, and that of meropenem resistance also increased sharply from 0.3% in 2015 to 17% in 2017 (p < 0.01). All meropenem-resistant strains carried a plasmid-borne gene. Among the colistin-resistant strains, three types of -bearing plasmids were determined. Plasmid sequencing indicated that these and -bearing plasmids were structurally similar to those commonly recovered from clinical isolates. Interestingly, both -bearing and -bearing plasmids were transferrable to strain J53 under selection by meropenem, yet only -bearing plasmids were transferrable under colistin selection.ConclusionThese findings might suggest that mobile elements harbouring and have been acquired by animal strains and transmitted to our food products, highlighting a need to prevent a spike in the rate of drug resistant food-borne infections.