A single colony of fresh bacterial culture from MacConkey agar was picked and inoculated into 3 mL of sterile Luria–Bertani (LB) medium at 37°C for 24 h in an incubator. Total DNA was extracted by a conventional boiling method. E. coli isolates were used to find out ESBL genes (blaCTX-M, blaTEM, and blaSHV) as well as COL-resistant genes mcr-1 to mcr-9. All ESBL-positive isolates were further screened for the detection of major blaCTX-M groups (i.e., blaCTX-M1, blaCTX-M-2, blaCTX-M-8, blaCTX-M-9, and blaCTX-M-25), using a multiplex PCR approach with specific primers, as previously defined Table S1. PCR amplicons were sequenced in TSKINGNE Corporation (Nanjing, China). Specific blaCTX-M alleles were identified using the online database for Genomic Epidemiology (https://cge.cbs.dtu.dk/services/ResFinder/), which is using to detect acquired AMR and chromosomal mutations in sequenced isolates of bacteria.