Biliary Infections in Cholangitis

Primary Bacterial Pathogens

Biliary infections in cholangitis are typically polymicrobial, with Gram-negative bacteria predominating, including Escherichia coli, Klebsiella, Pseudomonas, and Bacteroides species, along with Gram-positive organisms such as Enterococcus and Streptococcus species 1, 2, 3
Klebsiella species are consistently among the top three pathogens 1, 2
Pseudomonas aeruginosa is particularly important in healthcare-associated infections and patients with indwelling biliary tubes 1, 2
Bacteroides species (including B. fragilis) are recovered in 15-30% of patients, especially those with biliary-enteric anastomoses 1, 2
Enterococcus species (particularly E. faecalis) are common biliary pathogens, though their pathogenicity remains somewhat controversial 1, 2
Streptococcus species (including S. pneumoniae and S. pyogenes) are isolated less frequently 1, 2

Candida species are isolated from bile in 12-20% of patients with PSC undergoing ERCP, particularly those with advanced disease and high-grade stenosis 1
Biliary candidiasis is associated with markedly reduced transplant-free survival and increased risk of cholangiocarcinoma 1
Risk factors for biliary candidiasis include age at diagnosis, number of ERCPs, immunosuppression, and prolonged biliary obstruction 1, 4, 5
Aspergillus is rarely detected in biliary infections 1

Aminopenicillin/beta-lactamase inhibitor (e.g., ampicillin-sulbactam) provides adequate oral coverage for Gram-negative and Gram-positive organisms 1, 2, 4
Piperacillin-tazobactam covers Gram-negatives, Gram-positives, and anaerobes without additional agents 4, 5
Carbapenems (meropenem, imipenem/cilastatin, ertapenem) are alternatives for critically ill patients or those with ESBL risk factors 4, 5
Third-generation cephalosporins require additional anaerobic coverage 1, 2

Fluoroquinolones should be avoided as first-line therapy due to high resistance rates and unfavorable side effects, despite their excellent biliary penetration 1, 2
Anaerobic coverage is essential in patients with biliary-enteric anastomoses, elderly patients, or those in serious clinical condition 1, 2
Antibiotics alone are insufficient without biliary decompression—obstruction must be addressed for successful treatment 1, 2, 3, 4, 5
Fungal infection must be considered in immunocompromised patients or those with persistent symptoms despite appropriate bacterial coverage 1, 4, 5