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.

Extended-Spectrum Beta-Lactamase Escherichia coli-Associated Acute Cholangitis: Uncommon Patient Characteristics and Clinical Implications

Acute cholangitis is a potentially life-threatening condition caused by an infection of the biliary tract resulting from biliary obstruction. This case report highlights an unusual presentation of acute cholangitis in an elderly patient characterized by the presence of extended-spectrum beta-lactamase-producing Escherichia coli. We aim to emphasize the significance of recognizing diverse clinical manifestations in the elderly population to enhance timely diagnosis and appropriate management. The case highlights the importance of better understanding patient risk factors for potential causative organisms and their susceptibility to selecting proper antibiotics and improving clinical outcomes.

hirae Causing Biliary Tract Infection in a Patient with Cholangiocarcinoma: A Case Report

INTRODUCTION

E. faecium and E. faecalis are the common species of Enterococcus responsible for the majority of infections. Earlier, species other than the common ones were usually unidentified and reported as Enterococcus species. However, modern equipment, like MALDI-TOF and VITEK2, have been utilitarian, helping us to identify the previously unidentified species. E. hirae is an organism seldom reported to cause human infections. Here, we report a case of a biliary tract infection in a female patient with cholangiocarcinoma caused by E. hirae.

CASE

A 56-year-old female presented with fever and abdominal pain. Bile aspirated during the ERCP was received in our laboratory. The gram stain of the bile sample revealed abundant polymorphonuclear leucocytes along with gram-positive diplococci. The organism failed to grow on MacConkey agar. On blood agar, non-hemolytic colonies grew. The organism was identified as E. hirae by MALDI-TOF MS. The antibiotic susceptibility performed using VITEK2 revealed it to be resistant to high-level gentamicin and susceptible to all remaining drugs. She was successfully treated with oral ciprofloxacin for the infection.

DISCUSSION

Bile is colonized with bacteria due to obstruction in the biliary tree, leading to cholangitis. This causes bacterial proliferation and translocation of bacteria into the systemic circulation. Our case was resistant to high-level gentamicin, while all previously reported cases were susceptible. The resistant isolates of E. hirae being isolated from cattle and their surroundings amidst the rampant use of antibiotics in livestock can pose a difficult situation for humans. Thus, there should be regulations on antibiotic usage in livestock. Cases like these should be reported and recognized for their potential to cause outbreaks if they remain unreported.

CONCLUSION

Thus, E. hirae, when encountered, should not be ignored but considered a pathogen and reported. The presence of drug-resistant organisms in cattle and their surroundings, their zoonotic potential to cause infections in humans, and the uncontrolled usage of antibiotics in livestock are causes for concern. Thus, we need to be more vigilant regarding it in the future.

Risk Factors and Predictive Score for Bacteremic Biliary Tract Infections Due to Enterococcus faecalis and Enterococcus faecium: a Multicenter Cohort Study from the PROBAC Project

Biliary-tract bloodstream infections (BT-BSI) caused by Enterococcus faecalis and E. faecium are associated with inappropriate empirical treatment and worse outcomes compared to other etiologies. The objective of this study was to investigate the risk factors for enterococcal BT-BSI. Patients with BT-BSI from the PROBAC cohort, including consecutive patients with BSI in 26 Spanish hospitals between October 2016 and March 2017, were selected; episodes caused by E. faecalis or E. faecium and other causes were compared. Independent predictors for enterococci were identified by logistic regression, and a predictive score was developed. Eight hundred fifty episodes of BT-BSI were included; 73 (8.5%) were due to target Enterococcus spp. (48 [66%] were E. faecium and 25 [34%] E. faecalis). By multivariate analysis, the variables independently associated with Enterococcus spp. were (OR; 95% confidence interval): cholangiocarcinoma (4.48;1.32 to 15.25), hospital acquisition (3.58;2.11 to 6.07), use of carbapenems in the previous month (3.35;1.45 to 7.78), biliary prosthesis (2.19;1.24 to 3.90), and moderate or severe chronic kidney disease (1.55;1.07 to 2.26). The AUC of the model was 0.74 [95% CI0.67 to 0.80]. A score was developed, with 7, 6, 5, 4, and 2 points for these variables, respectively, with a negative predictive value of 95% for a score ≤ 6. A model, including cholangiocarcinoma, biliary prosthesis, hospital acquisition, previous carbapenems, and chronic kidney disease showed moderate prediction ability for enterococcal BT-BSI. Although the score will need to be validated, this information may be useful for deciding empirical therapy in biliary tract infections when bacteremia is suspected. IMPORTANCE Biliary tract infections are frequent, and a significant cause of morbidity and mortality. Bacteremia is common in these infections, particularly in the elderly and patients with cancer. Inappropriate empirical treatment has been associated with increased risk of mortality in bacteremic cholangitis, and the probability of receiving inactive empirical treatment is higher in episodes caused by enterococci. This is because many of the antimicrobial agents recommended in guidelines for biliary tract infections lack activity against these organisms. To the best of our knowledge, this is the first study analyzing the predictive factors for enterococcal BT-BSI and deriving a predictive score.

Intestinal fatty acid-binding protein is a biomarker for diagnosis of biliary tract infection

Background and Aim

Biliary tract infection (BTI) is an inflammatory disease and commonly associated with bacteremia. Delays in diagnosis or treatment of BTI cause high morbidity and mortality. However, an early diagnosis depends on appropriate clinical investigations. Appropriate biomarkers are urgently needed to improve the BTI diagnostic rate. We hypothesized that intestinal fatty acid‐binding protein (I‐FABP) might be a potential biomarker for BTI diagnosis.

Methods

We examined data from subjects aged ≥18 years diagnosed with BTI, including cholangitis and cholecystitis, whose blood samples were adequate for I‐FABP and zonulin assessment. We also collected blood samples from healthy volunteers as the control group. We excluded subjects in both groups who received steroids, antibiotics, or probiotics within 1 month before hospital admission (BTI cohort) or participation in this research (controls). The main study endpoint was to compare the diagnostic ability of I‐FABP to detect BTI in comparison with high‐sensitivity C‐reactive protein (hs‐CRP) and zonulin.

Results

The study collected the data of 51 patients with BTI and 35 healthy subjects. The receiver operating characteristic (ROC) area under the curve (AUC) for I‐FABP was 0.884 (95% confidence interval [CI]: 0.814–0.954), numerically higher than that for hs‐CRP (0.880; 0.785–0.976) and zonulin (0.570; 0.444–0.697). We estimated that the optimal cutoff value of I‐FABP was 2.1 ng/mL (sensitivity: 0.804; specificity: 0.829) for the diagnosis of BTI.

Conclusions

In summary, this study suggests that I‐FABP may be a potential alternative biomarker to hs‐CRP for diagnosing BTI. Further research should verify the use of I‐FABP as a marker for BTI diagnosis, but also for other inflammatory diseases.

Enterococcal Infections the First Year after Liver Transplantation-A Prospective Cohort Study

This study aimed to investigate the incidence of enterococcal infections and determine risk factors associated with enterococcal bloodstream infection (BSI) within the first year post-liver transplantation (LTx). We included 321 adult liver transplant recipients transplanted from 2011 to 2019 in a prospective cohort study. Cumulative incidence of enterococcal infections and risk factors associated with BSI were investigated in a competing risk model and time-updated Cox models, respectively. A total of 223 enterococcal infections were identified in 89 recipients. The cumulative incidences of first enterococcal infection and first enterococcal BSI were 28% (95% CI (23-33)) and 11% (CI (7-14)), respectively. Risk factors associated with enterococcal BSI were previous infections in the biliary tract (HR, 33; CI (15-74); p < 0.001), peritoneum (HR, 8.1; CI (3-23); p < 0.001) or surgical site (HR, 5.5; CI (1.4-22); p = 0.02), recipient age (HR per 10 years increase, 1.2; CI (1.03-1.6); p = 0.03), and cold ischemia time (HR per one hour increase, 1.2; CI (1.1-1.3); p < 0.01). Enterococcal infections are highly prevalent the first year post-LTx, and recipients with enterococcal infections in the biliary tract, peritoneum, or surgical site are at increased risk of BSI. These findings may have implications for the choice of empiric antibiotics early post-LTx.

The Prevalence and Clinical Significance of Anaerobic Bacteria in Major Liver Resection

(1) Background: Anaerobic infections in hepatobiliary surgery have rarely been addressed. Whereas infectious complications during the perioperative phase of liver resections are common, there are very limited data on the prevalence and clinical role of anaerobes in this context. Given the risk of contaminated bile in liver resections, the goal of our study was to investigate the prevalence and outcome of anaerobic infections in major hepatectomies. (2) Methods: We retrospectively analyzed the charts of 245 consecutive major hepatectomies that were performed at the department of General, Visceral, and Transplantation Surgery of the University Hospital of Tuebingen between July 2017 and August 2020. All microbiological cultures were screened for the prevalence of anaerobic bacteria and the patients' clinical characteristics and outcomes were evaluated. (3) Results: Of the 245 patients, 13 patients suffered from anaerobic infections. Seven had positive cultures from the biliary tract during the primary procedure, while six had positive culture results from samples obtained during the management of complications. Risk factors for anaerobic infections were preoperative biliary stenting (p = 0.002) and bile leaks (p = 0.009). All of these infections had to be treated by intervention and adjunct antibiotic treatment with broad spectrum antibiotics. (4) Conclusions: Anaerobic infections are rare in liver resections. Certain risk factors trigger the antibiotic coverage of anaerobes.

Clinical Presentation and Incidence of Anaerobic Bacteria in Surgically Treated Biliary Tract Infections and Cholecystitis

(1) Background: Cholecystitis and cholangitis are among the most common diseases treated by general surgery. Gallstones lead to inflammation and bacterial infection of the biliary tract. Biliary infections can lead to live threatening bacteremia and liver abscesses. The true role of anaerobes remains unclear. (2) Methods: We retrospectively analyzed bacterial cultures from biliary samples obtained from bile ducts and gallbladders at our tertiary care center. Patient characteristics and clinical outcomes were analyzed. (3) Results: In our database of 1719 patients, 365 patients had microbial testing, of which 42 grew anaerobic bacteria. Anaerobes were more frequently cultured in patients with hepatic abscesses and gallbladder perforation. These patients were older and had more comorbidities than the control group. The overall outcomes of all patients were favorable and the resistance rate to commonly used antibiotics remained low. (4) Conclusions: Anaerobes in biliary tract infections appear to be underdiagnosed and more prevalent in the elderly with advanced disease. Due to low antibiotic resistance, the combination of source control and adjunct anti-infective treatment leads to favorable outcomes.

Antibiotics in the Biliary Tract: A Review of the Pharmacokinetics and Clinical Outcomes of Antibiotics Penetrating the Bile and Gallbladder Wall

Biliary tract infections (BTIs), including cholangitis and cholecystitis, are common causes of bacteremia. Bacteremic BTIs are associated with a mortality rate of 9-12%. The extent to which antibiotics are excreted in the bile and the ratio of their exposure to the minimum inhibitory concentration of the infecting organism are among the important factors for the treatment of BTIs. This review updates health care professionals on the distribution of antibiotics in the common bile duct, gallbladder, and gallbladder wall. Antibiotic efficacy in treating BTIs based on the latest available clinical studies is also discussed. The efficacy and pharmacokinetics of 50 antibiotics are discussed. Overall, most antibiotic classes exhibit biliary penetration that translates into clinical efficacy. Only seven antibiotics (amoxicillin, cefadroxil, cefoxitin, ertapenem, gentamicin, amikacin, and trimethoprim/sulfamethoxazole) had poor biliary penetration profiles. Three antibiotics (ceftibuten, ceftolozane/tazobactam, and doripenem) had positive clinical outcomes despite the lack of pharmacokinetic studies on their penetration into the biliary tract. Conflicting efficacy data were reported for ampicillin despite adequate biliary penetration, whereas conflicting pharmacokinetic data were reported with cefaclor and moxifloxacin. Even in the absence of supportive clinical studies, antibiotics with good biliary penetration profiles may have a place in the treatment of BTIs.

Phylogeny, Resistome, and Virulome of Escherichia coli Causing Biliary Tract Infections

Escherichia coli is the most frequent Gram-negative bacilli involved in intra-abdominal infections. However, despite high mortality rates associated with biliary tract infections due to E. coli, there is no study focusing on this pathogen. In this study, we have characterized a group of 15 E. coli isolates obtained from 12 patients with biliary tract infections. Demographic and clinical data of the patients were recovered. Phylogeny, resistome, and virulome analysis through whole genome sequencing and biofilm formation were investigated. Among the 15 E. coli isolates, no predominant sequence type (ST) was identified, although 3 of them belonged to unknown STs (20%). Resistance to ampicillin, amoxicillin/clavulanic acid, cotrimoxazole, and quinolones was more present in these isolates; whereas, third and fourth generation cephalosporins, carbapenems, amikacin, tigecycline, and colistin were highly active. Moreover, high diversity of virulence factors has been found, with sfa, fimH, and gad the most frequently detected genes. Interestingly, 26.6% of the E. coli isolates were high biofilm-producers. Altogether, our data characterized for the first time E. coli isolates associated with biliary tract infections in terms of genomic relationship, resistome, and virulome.

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

Background: Biliary tract infection (BTI) is a common complication in patients with biliary obstruction caused by various biliary tract disorders. To improve the management of patients with BTI, microbial profiles from bile cultures and antibiotic resistance patterns were evaluated in this six-year retrospective study. Methods: A total of 709 patients with various biliary tract disorders from January 2012 to December 2017 were enrolled in this study. Bile specimens were taken from intra-operative puncture or post-operative drainage for microbial culture under sterile conditions. Microbial culture, identification, and antibiotic resistance test were performed according to a standard routine. Results: Cultures were positive in 574 of 789 bile specimens (73%). Of all isolates, 386 were gram-negative bacilli (67%), 170 were gram-positive cocci (30%), and 18 were fungi (3%). The two most common micro-organisms were Escherichia coli (29%) and Klebsiella pneumoniae (16%), the extended-spectrum β-lactamases (ESBL) positivity rates of which were 52% and 21%, respectively. Both bacteria were highly resistant to commonly used antibiotic agents (penicillins, cephalosporins, and quinolones), and highly susceptible to carbapenems, amikacin, and piperacillin-tazobactam. Enterococcus (19%) was the next most common bacteria isolated from bile samples, mainly including Enterococcus faecium (8%) and Enterococcus faecalis (6%). These two bacteria were resistant to cefazolin and clindamycin but sensitive to teicoplanin, tigecycline, and vancomycin. Enterococcus faecium was more resistant than Enterococcus faecalis to most of the tested antibiotic agents. Annual statistical analysis showed that the frequency of gram-negative enteric bacteria was decreasing slowly, but that of gram-positive enterococci was increasing slowly. Moreover, the overall antibiotic resistance rates of the most common strains have been decreasing slowly over the past six years. Conclusions: Enterobacteriaceae (Enterococcus coli and Klebsiella pneumoniae) and Enterococcus (Enterococcus faecium and Enterococcus faecalis) were the common pathogenic bacteria causing BTI, which exhibited high resistance to routinely used antibiotic agents and were highly sensitive to piperacillin-tazobactam, carbapenem, amikacin, and vancomycin. The microbial profiles from bile and its antibiotic resistance patterns have changed, which will help in the empirical treatment of BTI.

Biliary tract infection and bacteraemia: presentation, structural abnormalities, causative organisms and clinical outcomes

BACKGROUND

Biliary tract infection is a common cause of bacteraemia and is associated with high morbidity and mortality. Few papers describe blood culture isolates, underlying structural abnormalities and clinical outcomes in patients with bacteraemia.

AIMS

To determine the proportion of bacteraemias caused by biliary tract infection and to describe patient demographics, underlying structural abnormalities and clinical outcomes in patients with bacteraemia.

DESIGN

Prospective cohort study.

METHODS

Biliary tract infection that caused bacteraemia was defined as a compatible clinical syndrome and a blood culture isolate consistent with ascending cholangitis. Patients aged 16 years and over were included in the study. From June 2003 to May 2005, demographic and clinical data were collected prospectively on all adult patients with bacteraemia. Radiological and endoscopic retrograde cholangiopancreatography findings were collected retrospectively.

RESULTS

In 49 patients, the biliary tract was the site of infection for 39/592 (6.6%) community-acquired and 19/466 (4.1%) hospital-acquired episodes of bacteraemia. Three patients had mixed bacteraemias, and four had recurrent bacteraemia. The proportion of patients presenting with a structural abnormality was 34/49 (69%), and, of these structural abnormalities, 18/34 (53%) were pre-existing or newly diagnosed malignancies. Gram-negative organisms caused 55/58 (95%) episodes of bacteraemia. The most common Gram-negative organisms were Escherichia coli (34/55; 62%) and Klebsiella pneumoniae (14/55; 26%). Of the E coli isolates, 6/34 (18%) were extended spectrum beta-lactamase producers or multiply drug resistant. Thirty-day mortality was 7/49 (14%). There was no difference in time taken to administer an effective antibiotic to survivors and non-survivors (0.86 vs 1.05 days, respectively, p = 0.92). Of the seven who died, four died from septic shock within 48 h of admission caused by "susceptible" Gram-negative organisms. Two others died from disseminated malignancy.

CONCLUSIONS

The proportion of bacteraemias caused by biliary tract infection was 5.5%. The most common infecting organisms were E coli and K pneumoniae. There was a strong association with choledocholithiasis and malignancies, both pre-existing and newly diagnosed. Death was uncommon but when it occurred was often caused by septic shock within 48 h of presentation.