Yi Li,1,2 Dan Li,3 Xiangning Huang,2 Shanshan Long,2 Hua Yu,2 Jie Zhang1,2 

1School of Medicine, University of Electronic Science and Technology of China, Chengdu, People’s Republic of China; 2Department of Laboratory Medicine, Sichuan Provincial Key Laboratory for Human Disease Gene Study and the Center for Medical Genetics, Sichuan Academy of Medical Sciences and Sichuan Provincial People’s Hospital, University of Electronic Science and Technology of China, Chengdu, People’s Republic of China; 3Department of Laboratory Medicine, Medical Center Hospital of Qionglai City, Chengdu, People’s Republic of China

Correspondence: Jie Zhang; Hua Yu, Email zhangjiespph@163.com; yvhua2002@163.com

Purpose: We analyzed the pathogenic bacteria and antibiotic resistance distributions in patients with biliary tract infections (BTI) using samples from the Antimicrobial Resistant Investigation Network of Sichuan Province (ARINSP) to promote the rational use of antibiotics to reduce multidrug resistance.
Patients and Methods: Participating hospitals identified isolates between 2017 and 2023 and conducted antimicrobial susceptibility tests. Isolated bacteria were identified and tested for drug sensitivity using MOLDI-TOF mass spectrometry system, VITEK automated drug sensitivity system and paper diffusion method, and the results were interpreted with reference to CLSI M100 30th edition standards. WHONET 5.6 was used to analyze the results.
Results: In total, 25,573 bacterial isolates were collected; 18,134 were Gram-negative (70.9%). The top five most frequently isolated bacteria were Escherichia coli (8,181/25,573; 32.0%), Klebsiella pneumoniae (3,247/25,573; 12.7%), Enterococcus faecium (2,331/25,573; 9.1%), Enterococcus faecalis (1,714/25,573; 6.7%), and Enterobacter cloacae (1,429/25,573; 5.6%). E. coli and E. faecalis slowly declined over time, while K. pneumoniae slowly increased; E. faecium frequency was stable; E. coli resistance to ampicillin was the highest among all antibiotics tested; resistance rates decreased with the addition of sulbactam. K. pneumoniae resistance to aztreonam, imipenem, meropenem, ertapenem, and chloramphenicol remained low. E. cloacae was highly resistant to cephalosporins, especially cefoxitin and cefazolin. E. faecalis’ resistance to teicoplanin remained low, decreasing from 6.9% in 2017 to 0.0% in 2019 before stabilizing.
Conclusion: The most frequently isolated bacteria from patients with BTIs were Enterobacteriaceae, including E. coli and K. pneumoniae, followed by E. faecium and E. faecalis. Isolates exhibited high resistance to routinely used antibiotics (cephalosporins) and were highly sensitive to tigecycline, carbapenem, amikacin, and vancomycin. The results guide the rational use and continual revision of antibiotic regimens for BTIs to reduce antibiotic resistance.

Keywords: biliary tract infection, bile culture, antimicrobial resistance, microbial profiles