A total of 97 non-duplicated clinical E. coli isolates were collected from 97 different patients in various departments (gastroenterology, urology, endocrinology, neurosurgery, and other wards) of the First Affiliated Hospital of Chengdu Medical College, Chengdu, Sichuan, China from 2015 to 2016. The isolates were identified using standard laboratory methods and the ATB New system (bioMérieux, Lyons, France). Patients who satisfied the following three criteria were included in the analysis: 1) age >18 years; 2) suspected of having an infection, based on their clinical symptoms (e.g. fever, abdominal pain, nausea, vomiting, dehydration and tenesmus); and 3) their bacterial culture yielded E. coli. The E. coli isolates were collected from biofluid samples including blood, urine, sputum, wound exudates and abscesses. Each isolate was further verified by PCR amplification of a 369-bp internal control region from the E. coli marker gene, alr.15 (link) All bacterial strains were stored at −80 °C and were grown on MacConkey Agar (Oxoid, Hampshire, UK).
The study protocol was approved by the Ethics Committee of Chengdu Medical College, in accordance with the Helsinki declaration. In all cases, the patients or their family members were informed and their written consents was obtained.