Objective To investigate and characterize the antibiotic resistance, antibiotic resistance genes, and multi-locus sequence typing (MLST) of non-O157 Shiga toxin-producing Escherichia coli (STEC) isolated from livestock in Jiangsu.
Methods In May 2019, a total of 301 stool samples, including 231 sheep stool samples and 70 cattle stool samples, were collected in Dongtai of Jiangsu province for the isolation of non-O157 STEC. The modified micro broth method was used to determine the minimum inhibitory concentration (MIC) of 21 antibiotics to the isolates. The serotypes, antibiotic resistance genes and MLST of the isolates were analyzed by whole-genome sequencing (WGS).
Results The drug sensitivity test showed that of the 68 non 157-STEC strains, 32 were at least resistant to one antibiotic. It was found that STEC showed the highest resistance rate to tetracycline (42.6%), followed by azithromycin (36.8%), trimethoprim-sulfamethoxazole (TMP/SMX) (35.3%), streptomycin (32.3%), chloramphenicol (30.9%) and ciprofloxacin (29.4%). A total of 25 AMR genes were identified. The majority of STEC isolates carried the antibiotic resistance genes associated with aminoglycoside (44.1%), TMP/SMX (44.1%), and tetracycline (42.6%). MLST showed that the isolates were divided into 13 sequence types (STs), among which ST43 (19.1%) and ST155 (16.2%) had higher proportions. The minimum spanning tree (MST) indicated that most STEC strains with the same serotypes were clustered together. Four STs of STEC strains, including ST25, ST40, ST43 and ST675, were clustered with HUSEC strains.
Conclusion The antibiotic resistance of non-O157 STEC in livestock is complex, and there are multi-drug resistant strains. In addition, STEC strains in this area pose a potential threat to the population, and close attention needs to be paid to livestock, as an important host of non-O157 STEC.
Home
DownLoad: