Clinical and microbiological characteristics of patients with biliary disease

Biliary diseases are common digestive system disorders which may combine with biliary tract infection such as cholecystitis or cholangitis. Thus, rapid identification of the bacteria and their antibiotic susceptibility profiles are crucial for reducing the mortality of patients with biliary tract infection.

To identify bacterial species and antibiotic susceptibility for antibacterial therapy and analyze bile cultivation risk factors for increasing detection rates.

This retrospective study was conducted from July 2008 to July 2017. In total, 1339 bile samples which were collected during therapeutic endoscopic retrograde cholangiopan-creatography or percutaneous transhepatic cholangiodrainage or other biliary surgeries or biliary drainage were obtained to characterize pathogen spectra, antibiotic susceptibility, and clinical features. Clinical data including age, sex, comorbidities, clinical symptoms, protopathies, and history of biliary tract diseases and surgeries were collated from hospital medical records. Species identification and initial drug susceptibility were further identified by biochemical characterization using the VITEK 2 Compact test.

Positive microbiological findings were observed in 738 samples. The most frequently encountered strains were gram-negative bacteria (74.94%), including Escherichia coli (37.78%), Pseudomonas aeruginosa (8.96%), and Klebsiella pneumoniae (10.29%). Bile bacteria were largely sensitive to carbapenems, piperacillin/tazobactam, and gentamicin. Gram-negative strains had low susceptibility to ceftriaxone, quinolones and ampicillin. Almost the same micro-organisms were present in patients with malignant and benign diseases. The number of samples with Klebsiella pneumoniae in the bile culture were significantly different between patients with malignant and benign diseases (55 vs 30; P = 0.019). Age (P < 0.001), fever (P < 0.001), history of biliary tract diseases and surgeries (both P < 0.001), benign disease (P = 0.002), and the comorbidity chronic renal insufficiency (P = 0.007) affected the positive rates of the bile samples.

Gram-negative bacteria were the most commonly isolated biliary bacteria. We determined the major factors associated with positive detection rates. Microbiological analysis of bile samples allowed accurate antibiotic treatments.