Changes in Microbial Profiles and Antibiotic Resistance Patterns in Patients with Biliary Tract Infection over a Six-Year Period

Temporal Shifts in Etiological Agents and Antibiotic Resistance Patterns of Biliary Tract Infections in Sichuan Province, China (2017-2023)

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.

Epidemiological, clinical and microbiological characteristics of patients with biliary tract diseases with positive bile culture in a tertiary hospital

PURPOSE

The prevalence of biliary tract diseases, which are common gastrointestinal disorders, is steadily rising. If it progresses to sepsis or septic shock, it can endanger the patient's life. Therefore, it is crucial to promptly diagnose bacterial infection in individuals suffering from biliary diseases and comprehend the risk factors associated with infection. The objective of this study was to examine the types of bacteria present in the bile of patients with biliary tract diseases, assess any alterations in their susceptibility to antimicrobial agents, and identify the risk factors contributing to the development of infection in these patients.

PATIENTS AND METHODS

From June 2019 to November 2022, 317 patients of biliary tract diseases with positive bile culture were included in this hospital-based descriptive analysis. The hospital's computerized medical records were used to collect data on demographic information (including gender, age, and occupation), laboratory, and clinical findings, physical examination results, comorbidities, basic diseases, treatment history, complications, and in-hospital outcomes. The study followed the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) principles.

RESULTS

Of the 317 patients with positive biliary tract diseases, 247 had benign diseases and 70 had malignant diseases. Patients with benign disease experienced a higher prevalence of statistically significant symptoms such as abdominal pain (81.4% vs. 57.1%, P = 0.000), nausea (31.2% vs. 14.3%, P = 0.005), vomiting (30.0% vs. 12.9%, P = 0.004), and chills (10.9% vs. 2.9%, P = 0.039), while jaundice (12.6% vs. 37.1%, P = 0.000) was more common in patients with malignant disease. At the species level, Escherichia coli (105; 40.5%), Klebsiella pneumoniae (41; 15.8%), and Pseudomonas aeruginosa (30; 11.6%) were the most commonly found Gram-negative bacterial strains in biliary tract infection. Escherichia coli, Klebsiella pneumoniae, and Pseudomonas aeruginosa were most susceptible to tigecycline, ertapenem and ceftazidime/avibactam, respectively.

CONCLUSION

Gram-negative bacteria are the most commonly isolated biliary bacteria. Clinical doctors should pay attention to patients with malignant diseases with low hemoglobin, high total bilirubin and high alkaline phosphatase. Carbapenems, tigecycline, and minocycline are the recommended antibiotics for Enterobacteriaceae. In recent years, the proportion of enterococcus has gradually increased, and clinical attention should be paid to enterococcus infection. Linezolid and vancomycin were recommended for the treatment of Enterococci infections. Overall, this work can provide reference for clinical diagnosis, treatment and effective interventions.

ERCP endoscopic minimally invasive treatment of acute suppurative obstructive cholangitis: A study of 47 patients

The primary objective of the present study was to investigate the efficacy and safety of endoscopic therapy for acute obstructive suppurative cholangitis (AOSC) in patients with different underlying conditions. The present study comprised 47 patients diagnosed with AOSC, with a mean age of 70±14 years. Minimally invasive endoscopic treatments, including endoscopic duodenal papillary sphincterotomy, endoscopic duodenal nasobiliary drainage and/or placement of an endobiliary duct stent drainage tube, were performed. Variations in the levels of the white blood cell count, liver function, procalcitonin (PCT) and carbohydrate antigen-199 (CA199) were examined, compared and evaluated both prior to and following endoscopic retrograde cholangiopancreatography (ERCP). Among the 47 patients, 45 had a high fever, although their body temperature returned to normal after 7 days of ERCP treatment. The infection was difficult to control completely in two cases, including one case of biliary anastomosis secondary tumor with stenosis and AOSC and another case of an elderly patient with multiple choledocholithiasis complicated with sepsis. Within 7 days following treatment, the abdominal pain was resolved in 27 patients and jaundice subsided in 29 patients. On the 7th day after endoscopic treatment, the blood leukocyte, liver function, PCT and CA-199 parameters of all patients were significantly improved compared with those at admission. A total of 35 bile cultures yielded positive results, with Escherichia coli accounting for 11 cases (31.4%), Klebsiella pneumoniae accounting for 7 cases (20%), Pseudomonas aeruginosa accounting for 5 cases (14.3%), Enterococcus faecus accounting for 4 cases (11.4%) and other strains making up the remaining 17 cases. No serious complications were encountered with these patients, such as perforation, bleeding, severe pancreatitis or mortality, following ERCP. In conclusion, ERCP has been shown to be a safe and effective minimally invasive treatment method for elderly patients with AOSC, yielding a high rate of success.

Variability of bile bacterial profiles and drug resistance in patients with choledocholithiasis combined with biliary tract infection: a retrospective study

Background

Biliary tract infection is a common complication of choledocholithiasis. This study aimed to analyse the distribution of pathogenic bacteria in bile cultures from patients with choledocholithiasis combined with biliary tract infection to guide clinical application of antimicrobials and reduce the emergence of drug resistance.

Methods

A total of 880 patients were enrolled in this retrospective study from 30 March 2017 to 31 August 2022 at the Affiliated Hospital of Qingdao University in China. Bile specimens were extracted for microbiological culture under aseptic conditions using endoscopic retrograde cholangiopancreatography. Bacterial culture, strain identification, and antimicrobial susceptibility testing were conducted according to the standard protocol. Baseline data were retrieved from patient files.

Results

Overall, 90.34% (795/880) of bile samples showed positive microbiological results and 37.50% (330/880) demonstrated polymicrobial infections. Among the 795 bile specimens with positive culture results, 1,216 pathogenic bacteria were detected, with gram-negative bacilli accounting for 56.33%, gram-positive cocci for 41.86%, and fungi for 1.81%. The predominant gram-negative bacilli in the bile cultures were Escherichia coli (30.43%) and Klebsiella pneumoniae (13.98%), whereas the main gram-positive cocci were Enterococcus faecium (14.04%) and E. casseliflavus (4.28%). The annual trend analysis revealed a gradual decrease in the proportion of gram-negative bacilli and a gradual increase in the proportion of gram-positive cocci, with a concomitant decrease in the dominance of E. coli. Both E. faecium and E. coli showed high resistance to conventional antibiotics but high sensitivity to piperacillin/tazobactam, carbapenems, amikacin, and vancomycin.

Conclusions

A significant change has occurred in the bile bacterial spectrum in patients with choledocholithiasis and biliary tract infection. The incidence of gram-positive cocci infections has increased annually, while that of gram-negative bacilli and E. coli infections has decreased. Antibiotic administration should be tailored based on the local bacterial profile.

The profile of genome-wide DNA methylation, transcriptome, and proteome in streptomycin-resistant Mycobacterium tuberculosis

Streptomycin-resistant (SM-resistant) Mycobacterium tuberculosis (M. tuberculosis) is a major concern in tuberculosis (TB) treatment. However, the mechanisms underlying streptomycin resistance remain unclear. This study primarily aimed to perform preliminary screening of genes associated with streptomycin resistance through conjoint analysis of multiple genomics. Genome-wide methylation, transcriptome, and proteome analyses were used to elucidate the associations between specific genes and streptomycin resistance in M. tuberculosis H37Rv. Methylation analysis revealed that 188 genes were differentially methylated between the SM-resistant and normal groups, with 89 and 99 genes being hypermethylated and hypomethylated, respectively. Furthermore, functional analysis revealed that these 188 differentially methylated genes were enriched in 74 pathways, with most of them being enriched in metabolic pathways. Transcriptome analysis revealed that 516 genes were differentially expressed between the drug-resistant and normal groups, with 263 and 253 genes being significantly upregulated and downregulated, respectively. KEGG analysis indicated that these 516 genes were enriched in 79 pathways, with most of them being enriched in histidine metabolism. The methylation level was negatively related to mRNA abundance. Proteome analysis revealed 56 differentially expressed proteins, including 14 upregulated and 42 downregulated proteins. Moreover, three hub genes (coaE, fadE5, and mprA) were obtained using synthetic analysis. The findings of this study suggest that an integrated DNA methylation, transcriptome, and proteome analysis can provide important resources for epigenetic studies in SM-resistant M. tuberculosis H37Rv.

Clinico-epidemiological characteristics of the biliary samples and their antibiotic susceptibility pattern at a teaching hospital in Northern India

Introduction

Bile is deemed a sterile fluid, with the presence of clinical conditions like cholelithiasis, cholecystitis, previous biliary interventions, biliary strictures, and so on, leading to bile stasis, and increases the chances of bacteriobilia. In this study, we recognize the bacterial spectrum of microorganisms isolated from bile samples, diagnostic parameters, and antibiotic sensitivity patterns.

Methods

A retrospective observational study was carried out by compiling data from the hospital information system of a tertiary care center from 2021 to 2022 to evaluate biliary infections in patients who underwent surgical procedures related to the biliary tract and associated organs.

Results

A total of 234 patients' bile samples were included in our study. The mean age of patients was 48.04 ± 14.74 years, with more patients below the age of 65 years among those with infected bile samples. One hundred and sixty-three (163/234, 69.66%) patients infected by 209 pathogenic microorganisms were recognized. The most common microorganism isolated was Escherichia coli (83/209, 39.71%), followed by Pseudomonas aeruginosa (37/209, 17.7%). Acinetobacter baumannii and Klebsiella pneumoniae isolate owed to more than 90% penicillin, extended-spectrum beta-lactamase, carbapenem, and fluoroquinolone resistance among all isolates. Length of hospital stay, malignant obstruction, and chronic kidney disease were identified as statistically significant risk factors that lead to the isolation of multi-drug-resistant isolates from bile culture.

Conclusion

We recognized the spectrum of pathogens causing biliary tract infections at our center along with the antibiotic resistance pattern to guide and facilitate prompt and appropriate treatment by primary health care professionals and family medicine practitioners.

Comparison of bacterial profile of gallbladder with gallstones from patients undergoing cholecystectomy due to complicated and uncomplicated cholelithiasis: changes in the epidemiological scenario

INTRODUCTION

cholelithiasis is a highly prevalent disease of the digestive system in the world. In Brazil, it is a routine condition, whose studies suggest a prevalence of around 10% of adults. Colonization of bile and gallstone pathogens can occur when there is bacterial stasis and proliferation. This proliferation is facilitated by the adhesion and biofilm formation capacity of some bacteria. There are also lithogenic processes that involve bacterial participation. Studies have shown changes in the microbiota of the gallbladder of patients undergoing cholecystectomy, which may impact empirical treatment with antibiotics.

METHODOLOGY

microbiological analyzes of the sonication fluid of the gallstones and of two samples with bile were performed. Identification and antimicrobial susceptibility testing were performed according to a standard routine.

RESULTS

of the 34 patients, 76.4% were female. The age group was 48 years +/- 16.61. Acute cholecystitis occurred in 50% of cases. Bactobilia was evidenced in 32.1% of the cases. Klebisiella pneumoniae was noted as the most prevalent pathogen in acute cholecystitis; and Enterobacter sp, in cases of uncomplicated cholelithiasis. Greater sensitivity was obtained in the search for microorganisms in the sonication fluid samples of the stones in relation to the bile samples (p=0.0058).

CONCLUSION

there was a higher prevalence of bactobilia in patients with acute cholecystitis compared to those with uncomplicated cholelithiasis. The use of sonication in bacterial investigation proved to be superior to the conventional method and can be considered.

Multifactorial Analysis of Biliary Infection in Patients with Hepato-pancreatico-biliary and Associated Intraabdominal Malignancies Admitted to a Teaching Hospital in Northern India

Background

Blockage of the biliary tract is commonly caused by malignant tumors leading to deranged liver function, responsible for poor prognosis and a high rate of bacteriobilia leading to mortality.

Material and methods

We collected retrospective data from the hospital information system and laboratory registers in our department from 2021 to 2022 to evaluate biliary infections in patients with hepato-pancreatico-biliary and associated intraabdominal malignancies.

Result

A total of 118 (118/234, 50.43%) patients' bile samples were estimated in this study. Patients' average age was 53.02 ± 13.49 years, with more patients below the age of 65 years among those with infected bile samples. Eight patients were infected by 102 pathogenic microorganisms. The most common pathogenic microorganism responsible for biliary infection in patients with abdominal malignancies was Escherichia coli (38/102, 37.25%) followed by Klebsiella pneumoniae (21/102, 20.59%) and Enterococcus spp. (18/102, 17.65%). Underlying comorbidities like diabetes mellitus, hypothyroidism, hypoproteinemia, chronic liver disease, immunosuppression, chronic kidney disease, increased hospital stay, admission to the intensive care unit (ICU), and presence of percutaneous transhepatic biliary drain were statistically significant risk factors for isolation of multidrug-resistant pathogenic bacteria.

Conclusion

Our study guided physicians in identifying the associated demographic characteristics, risk factors, and the spectrum of pathogens responsible for bacteriobilia in abdominal cancer patients along with the antibiotic resistance pattern among these isolates and better selection of antibiotics and antibiotic prophylaxis for patients at risk of developing biliary tract infections with multidrug-resistant pathogens.

How to cite this article

Kar M, Dubey A, Patel SS, et al. Multifactorial Analysis of Biliary Infection in Patients with Hepato-pancreatico-biliary and Associated Intraabdominal Malignancies Admitted to a Teaching Hospital in Northern India. Euroasian J Hepato-Gastroenterol 2023;13(1):10-17.

Microbial spectrum and drug resistance of pathogens cultured from gallbladder bile specimens of patients with cholelithiasis: A single-center retrospective study

BACKGROUND

Bacterial infection is an important cause of cholelithiasis or gallstones and interferes with its treatment. There is no consensus on bile microbial culture profiles in previous studies, and identified microbial spectrum and drug resistance is helpful for targeted preventive and therapeutic drugs in the perioperative period.

AIM

To analyze the bile microbial spectrum of patients with cholelithiasis and the drug susceptibility patterns in order to establish an empirical antibiotic treatment for cholelithiasis-associated infection.

METHODS

A retrospective single-center study was conducted on patients diagnosed with cholelithiasis between May 2013 and December 2018.

RESULTS

This study included 185 patients, of whom 163 (88.1%) were diagnosed with gallstones and 22 (11.9%) were diagnosed with gallstones and common bile duct stones (CBDSs). Bile culture in 38 cases (20.5%) was positive. The presence of CBDSs (OR = 5.4, 95%CI: 1.3-21.9, P = 0.03) and longer operation time (> 80 min) (OR = 4.3, 95%CI: 1.4-13.1, P = 0.01) were identified as independent risk factors for positive bile culture. Gram-negative bacteria were detected in 28 positive bile specimens, and Escherichia coli (E. coli) (19/28) and Klebsiella pneumoniae (5/28) were the most frequently identified species. Gram-positive bacteria were present in 10 specimens. The resistance rate to cephalosporin in E. coli was above 42% and varied across generations. All the isolated E. coli strains were sensitive to carbapenems, with the exception of one imipenem-resistant strain. K. pneumoniae showed a similar resistance spectrum to E. coli. Enterococcus spp. was largely sensitive to glycopeptides and penicillin, except for a few strains of E. faecium.

CONCLUSION

The presence of common bile duct stones and longer operation time were identified as independent risk factors for positive bile culture in patients with cholelithiasis. The most commonly detected bacterium was E. coli. The combination of β-lactam antibiotics and β-lactamase inhibitors prescribed perioperatively appears to be effective against bile pathogens and is recommended. Additionally, regular monitoring of emerging resistance patterns is required in the future.

Klebsiella pneumoniae Bacteremia is Associated with Higher Mortality in Acute Calculous Cholangitis as Compared to Escherichia coli Bacteremia

BACKGROUND

Acute cholangitis (AC) is a potentially life-threatening infection involving the biliary system. The two commonest bacteria involved are Escherichia coli (EC) followed by Klebsiella pneumoniae (KP). Microbiology is a prognostic factor for several pathologies but not for AC. We aim to investigate clinical outcomes between KP bacteremia vs. EC bacteremia in AC.

METHODS

This is a retrospective cohort study of patients diagnosed with calculous AC (January-December 2016). Study outcomes include the length of hospitalization stay, in-hospital mortality, 30-day, and 90-day mortality. Univariate and multivariate logistic regression was used to establish correlations.

RESULTS

We included 141 patients (KP (n = 29), EC (n = 112)) with overall median age of 82.2 and similar gender distribution. Most patients had Grade II AC (n = 59, 41.8%). Patient demographics were comparable. KP bacteremia had lower median platelet count (KP:168 × 109/L vs. EC:200 × 109/L; p = 0.025). Overall 30-day and 90-day mortality were 9.2 and 10.6%, respectively. Multivariate analysis showed KP bacteremia had higher 30-day (Odds ratio (OR) 6.09, (95% Confidence Interval (CI):1.27-29.10), p = 0.024) and 90-day mortality (OR 6.10, 95% CI: 1.39-26.76, p = 0.017). The length of hospitalization stay was comparable. Subgroup analysis of endoscopic retrograde cholangiopancreatogram patients showed comparable outcomes.

CONCLUSION

KP bacteremia is associated with lower platelet count and higher 30-day and 90-day mortality than EC. More studies are required to establish if inferior outcomes of KP bacteremia are associated with antimicrobial resistance.

A Retrospective Study on Bile Culture and Antibiotic Susceptibility Patterns of Patients with Biliary Tract Infections

Aim

This study aimed to provide profiles of microorganisms isolated from bile and antibiotic susceptibility patterns of biliary tract infections (BTIs) in our center.

Methods

A total of 277 patients diagnosed with BTIs at the Second Affiliated Hospital of Harbin Medical University from 2011 to 2018 were included in this study. Medical records were reviewed to obtain clinical and demographic data. Bile specimens were prepared through endoscopic retrograde cholangiopancreatography (ERCP), percutaneous transhepatic cholangiodrainage (PTCD), and percutaneous transhepatic gallbladder drainage (PTGD) under aseptic conditions. In those with positive bile culture results, blood cultures were concurrently conducted. The concordance of the results between bile culture and blood culture were also analysed.

Results

Two hundred and sixty-seven bile cultures were positive, while 280 strains of micro-organisms were isolated. Among these, 76.8% were Gram-negative, 22.5% were Gram-positive and 0.7% were fungi. The most common microorganisms were Escherichia coli, Klebsiella pneumoniae, and Enterococcus faecalis. Gram-negative bacteria we tested were highly sensitive to ertapenem, imipenem, tigecycline, and amikacin. Gram-positive bacteria we tested were highly sensitive to tigecycline, teicoplanin, linezolid, vancomycin, and chloramphenicol. For the 44 patients with positive bile cultures, a blood culture was also performed. Among them, 29 cases yielded positive blood culture results. Among those cases with positive blood culture, 48.3% showed complete agreement with bile culture, 3.4% showed partial agreement, and 48.3% showed disagreement. The most common microorganisms in blood culture were the same as in bile culture. Additionally, the proportion of Staphylococcus epidermidis was significantly higher in blood culture (P < 0.05).

Conclusion

Our study provided a comprehensive analysis of the bacteria distribution and drug resistance profiles in patients with BTIs in northern China. Further studies should be conducted to validate our findings.

Alterations of gut microbiome and metabolite profiles in choledocholithiasis concurrent with cholangitis

BACKGROUND AND AIMS

Gut microbiota and their metabolic products might play important roles in regulating the pathogenesis of choledocholithiasis concurrent with cholangitis (CC). The aim of this study was to explore the characteristic gut dysbiosis, metabolite profiles and the possible roles in patients with CC.

METHODS

A case-control study was carried out to analyze the alterations in the intestinal microbiota and their metabolites in patients with CC (n = 25) compared with healthy controls (HCs) (n = 25) by metagenomic sequencing to define the gut microbiota community and liquid chromatography/mass spectrometry (LC/MS) analysis to characterize the metabolite profiles.

RESULTS

Significantly reduced Shannon diversity index (p = 0.043) and differential overall fecal microbiota community in CCs were observed. Twelve dominant altered species were identified and analyzed (LDA score > 3.0, p < 0.05) (Q value < 0.05), including unclassified_f_Enterobacteriaceae, Escherichia_coli, Roseburia_faecis and Eubacterium rectale. Moreover, the levels of KEGG pathways related to biofilm formation of Escherichia coli, lipopolysaccharide (LPS) biosynthesis, and the metabolism of propanoate and glutathione in CCs were significantly altered. Finally, 47 markedly changed metabolites (VIP > 1.0 and p < 0.05), including low level of kynurenic acid (KYNA) and high concentration of N-palmitoylsphingosine involving tryptophan metabolism and sphingolipid signaling pathways, were identified to validate aberrant metabolic patterns in CCs, and multiple correlated metabolic modules involving bile inflammation were altered in CCs.

CONCLUSION

Our study provides novel insights into compositional and functional alterations in the gut microbiome and metabolite profiles in CC and the underlying mechanisms between gut microbiota and bile inflammation.

The Great ESKAPE: Exploring the Crossroads of Bile and Antibiotic Resistance in Bacterial Pathogens

Throughout the course of infection, many pathogens encounter bactericidal conditions that threaten the viability of the bacteria and impede the establishment of infection. Bile is one of the most innately bactericidal compounds present in humans, functioning to reduce the bacterial burden in the gastrointestinal tract while also aiding in digestion. It is becoming increasingly apparent that pathogens successfully resist the bactericidal conditions of bile, including bacteria that do not normally cause gastrointestinal infections. This review highlights the ability of Enterococcus, Staphylococcus, Klebsiella, Acinetobacter, Pseudomonas, Enterobacter (ESKAPE), and other enteric pathogens to resist bile and how these interactions can impact the sensitivity of bacteria to various antimicrobial agents. Given that pathogen exposure to bile is an essential component to gastrointestinal transit that cannot be avoided, understanding how bile resistance mechanisms align with antimicrobial resistance is vital to our ability to develop new, successful therapeutics in an age of widespread and increasing antimicrobial resistance.

Clinical and microbiological characteristics of patients with biliary disease

BACKGROUND

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.

AIM

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

METHODS

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.

RESULTS

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.

CONCLUSION

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.