The Evolving Microbiology and Antimicrobial Resistance in Peritonitis of Biliary Origin: An Evidence-Based Update of the Tokyo Guidelines (TG18) for Clinicians.

Background

Biliary peritonitis is a severe intra-abdominal emergency with high mortality. Effective management requires source control and appropriate antimicrobial therapy.

Methods

This review synthesizes recent literature (2016-2025), as well as established guidelines recommendations on the evolving microbiology and antimicrobial resistance patterns in biliary tract infections, as data on biliary peritonitis is scarce and relatively heterogeneous.

Results

The microbiological landscape is stratified by patient history. Community-acquired infections are typically caused by Escherichia coli, Klebsiella pneumoniae, and Enterococcus spp. In contrast, healthcare-associated infections show a shift, with highly resistant pathogens such as Pseudomonas aeruginosa, and a tendency towards polymicrobial infections. The rise of multidrug-resistant (MDR) organisms, including extended-spectrum β-lactamase (ESBL)-producing Enterobacterales, Carbapenem-Resistant Enterobacterales (CRE), and Vancomycin-Resistant Enterococci (VRE), is a critical challenge limiting therapeutic options. Resistance patterns vary geographically, necessitating the use of local data.

Conclusions

This review argues for a paradigm shift from severity-based guidelines to a dual-axis model incorporating resistance risk factors (prior healthcare exposure, previous biliary interventions, a history of MDR infections). We propose a risk-stratified approach to empiric antibiotic selection, emphasizing microbiological diagnostics for therapy de-escalation. Future research should focus on prospective studies, novel antibiotics, and rapid diagnostics.