A worrisome prevalence of extended-spectrum β-lactamase producers in patients with biliary obstruction and cholangitis: Phenotypic and molecular characterization of biliary Escherichia coli and Klebsiella pneumoniae isolates.

Background & Aims: The alarming rise of antibiotic resistance presents a substantial and worrisome issue within the context of biliary obstruction, specifically in the treatment of cholangitis. This abovementioned scenario underscores the critical importance of addressing extended spectrum β-lactamase (ESBL) producers in the biliary system to adequately tackle cholangitis using third-generation cephalosporins. Hence, we aimed to determine the frequency of ESBL and carbapenemases among biliary Escherichia coli and Klebsiella pneumoniae isolated from patients with biliary obstruction.

Methods: In this cross-sectional study, bile samples were collected via aspiration from patients diagnosed with biliary obstruction during the endoscopic retrograde cholangiopancreatography (ERCP) procedure. Subsequent culturing of these samples was performed, followed by phenotypic and molecular assessments for the detection of ESBL- and carbapenemase-producing strains of E. coli and K. pneumoniae.

Results: Approximately 23.5 % of patients with biliary obstruction harbored biliary ESBL-producers, with the majority (70.2 %) being diagnosed with cholangitis. Moreover, 2.1 % of patients had biliary carbapenemase-producing K. pneumoniae strains. Molecular analysis confirmed the high prevalence of bla and bla in E. coli, and bla and bla in K. pneumoniae. Additionally, the presence of biliary K. pneumoniae harboring bla, bla, and bla was observed.

Conclusion: Our study reveals a noteworthy observation that over half of patients experiencing biliary obstruction harbor ESBL-producing bacteria in their biliary tract. Notably, we discovered a significant link between ESBL producers and the risk of cholangitis. These findings raise important concerns regarding the suitability of employing third-generation cephalosporins as initial treatment for cholangitis and other similar biliary infections.