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

Antibiotic pharmacokinetics in infected pleural effusions

Pleural infection is usually treated with empirical broad-spectrum antibiotics, but limited data exist on their penetrance into the infected pleural space. We performed a pharmacokinetic study analysing the concentration of five intravenous antibiotics across 146 separate time points in 35 patients (amoxicillin, metronidazole, piperacillin-tazobactam, clindamycin and cotrimoxazole). All antibiotics tested, apart from co-trimoxazole, reach pleural fluid levels equivalent to levels within the blood and well above the relevant minimum inhibitory concentrations. The results demonstrate that concerns about the penetration of commonly used antibiotics, apart from co-trimoxazole, into the infected pleural space are unfounded.

Biliary pharmacokinetic/pharmacodynamic analysis of continuous infusion meropenem/vaborbactam in a case series of orthotopic liver transplant recipients

OBJECTIVE

To analyse the biliary pharmacokinetics/pharmacodynamics (PK/PD) of continuous infusion (CI) meropenem-vaborbactam (MEM-VBM) in a case series of orthotopic liver transplant (OLT) recipients being treated for Klebsiella pneumoniae carbapenemase-producing Klebsiella pneumoniae (KPC-Kp) related biliary tract infections (BTIs) or as preemptive therapy of KPC-Kp rectal colonization.

METHODS

Critical OLT recipients receiving CI MEM-VBM (2 g/2 g q8h over 8 h) because of KPC-Kp related BTIs or as preemptive therapy of KPC-Kp rectal colonization, having Kehr's tube positioned and undergoing simultaneous therapeutic drug monitoring of MEM and VBM in plasma and bile were retrospectively assessed. Bile-to-plasma ratio of free steady-state concentrations (fCss) of MEM and VBM was used for assessing biliary penetration. Optimal joint MEM-VBM PK/PD target attainment was defined as MEM fCss/MIC ratio >4 coupled with VBM free area under time-concentration curve (fAUC)/threshold concentration (CT) ratio >24.

RESULTS

Overall, four critical OLT recipients were included. Median bile-to-plasma ratio was 0.32 for MEM (range 0.21-0.79) and 0.40 for VBM (range 0.20-0.77). Biliary MEM-VBM joint PK/PD target attainment was optimal in 3/4 OLT recipients and quasi-optimal in the other one.

CONCLUSIONS

The 1:1 proportion between MEM and VBM concentrations was maintained unchanged in the bile, allowing us to assume that the efficacy of MEM-VBM may be appropriate even in the treatment of BTIs. CI administration was an effective strategy for attaining aggressive biliary joint PK/PD targets against pathogens with an MIC up to 2 mg/L.

Updates on Antibiotic Regimens in Acute Cholecystitis

Acute cholecystitis is one of the most common surgical diseases, which may progress from mild to severe cases. When combined with bacteremia, the mortality rate of acute cholecystitis reaches up to 10-20%. The standard of care in patients with acute cholecystitis is early laparoscopic cholecystectomy. Percutaneous cholecystostomy or endoscopic procedures are alternative treatments in selective cases. Nevertheless, antibiotic therapy plays a key role in preventing surgical complications and limiting the systemic inflammatory response, especially in patients with moderate to severe cholecystitis. Patients with acute cholecystitis have a bile bacterial colonization rate of 35-60%. The most frequently isolated microorganisms are Escherichia coli, Klebsiella spp., Streptococcus spp., Enterococcus spp., and Clostridium spp. Early empirical antimicrobial therapy along with source control of infection is the cornerstone for a successful treatment. In these cases, the choice of antibiotic must be made considering some factors (e.g., the severity of the clinical manifestations, the onset of the infection if acquired in hospital or in the community, the penetration of the drug into the bile, and any drug resistance). Furthermore, therapy must be modified based on bile cultures in cases of severe cholecystitis. Antibiotic stewardship is the key to the correct management of bile-related infections. It is necessary to be aware of the appropriate therapeutic scheme and its precise duration. The appropriate use of antibiotic agents is crucial and should be integrated into good clinical practice and standards of care.

Management of intra-abdominal infections: recommendations by the Italian council for the optimization of antimicrobial use

Intra-abdominal infections (IAIs) are common surgical emergencies and are an important cause of morbidity and mortality in hospital settings, particularly if poorly managed. The cornerstones of effective IAIs management include early diagnosis, adequate source control, appropriate antimicrobial therapy, and early physiologic stabilization using intravenous fluids and vasopressor agents in critically ill patients. Adequate empiric antimicrobial therapy in patients with IAIs is of paramount importance because inappropriate antimicrobial therapy is associated with poor outcomes. Optimizing antimicrobial prescriptions improves treatment effectiveness, increases patients' safety, and minimizes the risk of opportunistic infections (such as Clostridioides difficile) and antimicrobial resistance selection. The growing emergence of multi-drug resistant organisms has caused an impending crisis with alarming implications, especially regarding Gram-negative bacteria. The Multidisciplinary and Intersociety Italian Council for the Optimization of Antimicrobial Use promoted a consensus conference on the antimicrobial management of IAIs, including emergency medicine specialists, radiologists, surgeons, intensivists, infectious disease specialists, clinical pharmacologists, hospital pharmacists, microbiologists and public health specialists. Relevant clinical questions were constructed by the Organizational Committee in order to investigate the topic. The expert panel produced recommendation statements based on the best scientific evidence from PubMed and EMBASE Library and experts' opinions. The statements were planned and graded according to the Grading of Recommendations Assessment, Development and Evaluation (GRADE) hierarchy of evidence. On November 10, 2023, the experts met in Mestre (Italy) to debate the statements. After the approval of the statements, the expert panel met via email and virtual meetings to prepare and revise the definitive document. This document represents the executive summary of the consensus conference and comprises three sections. The first section focuses on the general principles of diagnosis and treatment of IAIs. The second section provides twenty-three evidence-based recommendations for the antimicrobial therapy of IAIs. The third section presents eight clinical diagnostic-therapeutic pathways for the most common IAIs. The document has been endorsed by the Italian Society of Surgery.

Relationship between Intraoperative Bile Culture Outcomes and Subsequent Postoperative Infectious Complications: A Retrospective Cohort Study

The presence of positive bile culture during intraoperative procedures has been associated with elevated morbidity and mortality rates in hepatobiliopancreatic surgeries, contributing to increased healthcare expenditures. However, the precise impact of bactobilia on the development of postoperative complications remains uncertain due to existing disparities in the published literature. In this retrospective cohort study, we assessed 137 patients who underwent major hepatobiliopancreatic surgery to examine the relationship between intraoperative bile culture outcomes and subsequent postoperative infectious complications. Among patients with bactobilia, a significant 35.1% exhibited systemic or local infectious complications, whereas only 11.1% of those with negative culture results experienced any infectious complications (p = 0.002). Similarly, a notable difference was observed in the incidence of surgical site infections, with 24.3% in the bactobilia group compared to 7.9% in the negative culture group (p = 0.01). A total of 74 monomicrobial cultures with microbiological growth were isolated, predominantly featuring Gram-negative microorganisms, primarily Enterobacteriaceae in 49 cultures. Escherichia coli was identified in 37.8% of positive cultures, while Klebsiella pneumoniae was evident in 21.6%. Gram-positive microorganisms were present in 10 cultures, with Enterococcus emerging as the prevailing species. The logistic regression model identified a positive bile culture as an independent factor significantly associated with infection development (OR: 2.26; 95% confidence interval: 1.23-11; p = 0.02). Considering the limitations of the study, these findings underscore the critical importance of conducting bile cultures during the intraoperative phase to enable vigilant monitoring and prompt management of infectious complications.

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.

Selective and Concentrative Enteropancreatic Recirculation of Antibiotics by Pigs

Antibiotics that are efficacious for infectious pancreatitis are present in pancreatic exocrine secretion (PES) after intravenous administration and above minimal inhibitory concentrations. We measured concentrations of four antibiotics by tandem liquid chromatography-mass spectroscopy in plasma and PES after enteral administration to juvenile pigs with jugular catheters and re-entrant pancreatic-duodenal catheters. Nystatin, which is not absorbed by the intestine nor used for infectious pancreatitis (negative control), was not detected in plasma or PES. Concentrations of amoxicillin increased in plasma after administration (p = 0.035), but not in PES (p = 0.51). Metronidazole and enrofloxacin that are used for infectious pancreatitis increased in plasma after enteral administration and even more so in PES, with concentrations in PES averaging 3.1 (±0.5)- and 2.3 (±0.6)-fold higher than in plasma, respectively (p's < 0.001). The increase in enrofloxacin in PES relative to plasma was lower after intramuscular administration (1.8 ± 0.5; p = 0.001). The present results demonstrate the presence of a selective and concentrative enteropancreatic pathway of secretion for some antibiotics. Unlike the regulated secretion of bile, the constitutive secretion of PES and intestinal reabsorption may provide a continuous exposure of pancreas tissue and the small intestine to recirculated antibiotics and potentially other therapeutic molecules. There is a need to better understand the enteropancreatic recirculation of antibiotics and the associated mechanisms.

Physiologically Based Pharmacokinetic Modeling in Neonates: Current Status and Future Perspectives

Rational drug use in special populations is a clinical problem that doctors and pharma-cists must consider seriously. Neonates are the most physiologically immature and vulnerable to drug dosing. There is a pronounced difference in the anatomical and physiological profiles be-tween neonates and older people, affecting the absorption, distribution, metabolism, and excretion of drugs in vivo, ultimately leading to changes in drug concentration. Thus, dose adjustments in neonates are necessary to achieve adequate therapeutic concentrations and avoid drug toxicity. Over the past few decades, modeling and simulation techniques, especially physiologically based pharmacokinetic (PBPK) modeling, have been increasingly used in pediatric drug development and clinical therapy. This rigorously designed and verified model can effectively compensate for the deficiencies of clinical trials in neonates, provide a valuable reference for clinical research design, and even replace some clinical trials to predict drug plasma concentrations in newborns. This review introduces previous findings regarding age-dependent physiological changes and pathological factors affecting neonatal pharmacokinetics, along with their research means. The application of PBPK modeling in neonatal pharmacokinetic studies of various medications is also reviewed. Based on this, we propose future perspectives on neonatal PBPK modeling and hope for its broader application.

Biliary excretion and pharmacokinetics of several fluoroquinolones after intravenous injection in rabbits

The aim of this study was to measure the concentrations of enrofloxacin (ERFX) and other fluoroquinolones; orbifloxacin (OBFX), marbofloxacin (MBFX), and ofloxacin (OFLX) in the plasma and bile of rabbits after a single intravenous (IV) injection. Twenty male rabbits were divided into four groups and given each drug by IV injection into the ear vein at a dose of 5.0 mg/kg BW. The concentration of ERFX, ciprofloxacin (CPFX), OBFX, MBFX and OFLX in plasma and bile were determined by HPLC. CPFX, metabolite of ERFX, was also measured by HPLC in plasma and bile of rabbits receiving ERFX. Several pharmacokinetic parameters in plasma were calculated and biliary clearance (CLbile) was calculated from extent of biliary excretion and accumulation of AUC of each drug. After IV injection, elimination half-life (t1/2β) was 4.13, 3.68, 6.60, 5.14 hr; volume of distribution at a steady state (Vdss) was 1.24, 0.503, 0.771, 1.02 L/kg; and total body clearance (CLtot) was 1.05, 0.418, 0.271, 0.453 L/kg/hr, respectively. The values for CLbile for ERFX, OBFX, MBFX, and OFLX were 0.0048, 0.0050, 0.0057, and 0.0094 L/kg/hr, respectively. These values represent 0.48%, 1.2%, 2.1%, and 2.3% of the total body clearance (CLtot) of each drug, respectively. The biliary clearance of CPFX was also measured and found to be 0.0199 L/kg/hr with ERFX administration. The results showed that ERFX, OBFX, MBFX, and OFLX were not excreted into the bile to a significant extent, making them safe drugs to use in rabbits.

Circulating vitamin levels mediate the causal relationship between gut microbiota and cholecystitis: a two-step bidirectional Mendelian randomization study

Background

The relationship between gut microbiota and the occurrence of cholecystitis remains unclear. Existing research lacks a clear understanding of how circulating vitamin levels modulate this relationship. Therefore, our study aims to investigate whether circulating vitamin levels mediate the causal relationship between gut microbiota and cholecystitis using a two-step bidirectional Mendelian randomization approach.

Methods

In this study, we initially employed Linkage Disequilibrium Score Regression (LDSC) analysis to assess the genetic correlation of five circulating vitamin level genome-wide association study (GWAS) summary datasets, thereby avoiding potential sample overlap. Subsequently, we conducted a two-step analysis to investigate the causal effects between gut microbiota and cholecystitis. In the second step, we explored the causal relationship between circulating vitamin levels and cholecystitis and identified the mediating role of vitamin D. The primary method used for causal analysis was the inverse variance-weighted approach. We performed additional sensitivity analyses to ensure result robustness, including the cML-MA method and reverse Mendelian randomization (MR) analysis.

Results

An increment of one standard deviation in RuminococcaceaeUCG003 was associated with a 25% increased risk of cholecystitis (OR = 1.25, 95%CI = 1.01-1.54, p = 0.04), along with a 3% decrease in 25-hydroxyvitamin D levels (OR = 0.97, 95%CI = 0.944-0.998, p = 0.04). However, following the rigorous Bonferroni correction, every one standard deviation decrease in circulating vitamin D levels was associated with a 33% increased risk of cholecystitis (OR = 0.67, 95%CI = 0.49-0.90, p = 0.008, Padjust = 0.04). Thus, the potential link between gut microbiota and cholecystitis risk might be mediated by circulating vitamin D levels (proportion mediated = 5.5%). Sensitivity analyses provided no evidence of pleiotropy.

Conclusion

Our study results suggest that an elevated abundance of specific gut microbiota is associated with an increased susceptibility to cholecystitis, with the causal relationship being mediated by circulating vitamin D levels. Further large-scale randomized controlled trials are necessary to validate the causal effects of gut microbiota on cholecystitis risk. This study provides novel insights into cholecystitis prevention through the regulation of gut microbiota.

Managing the clinical effects of drug-induced intestinal dysbiosis with a focus to antibiotics: Challenges and opportunities

The term "intestinal dysbiosis" is used for indicating change(s) of the intestinal microbiota which have been associated with the development of diseases and the deterioration of disease treatments in humans. In this review, documented clinical effects of drug-induced intestinal dysbiosis are briefly presented, and methodologies which could be considered for the management of drug-induced intestinal dysbiosis based on clinical data are critically reviewed. Until relevant methodologies are optimized and/or their effectiveness to the general population is confirmed, and, since drug-induced intestinal dysbiosis refers predominantly to antibiotic-specific intestinal dysbiosis, a pharmacokinetically-based approach for mitigating the impact of antimicrobial therapy on intestinal dysbiosis is proposed.

Pathophysiological consequences and treatment strategy of obstructive jaundice

Obstructive jaundice (OJ) is a common problem in daily clinical practice. However, completely understanding the pathophysiological changes in OJ remains a challenge for planning current and future management. The effects of OJ are widespread, affecting the biliary tree, hepatic cells, liver function, and causing systemic complications. The lack of bile in the intestine, destruction of the intestinal mucosal barrier, and increased absorption of endotoxins can lead to endotoxemia, production of proinflammatory cytokines, and induce systemic inflammatory response syndrome, ultimately leading to multiple organ dysfunction syndrome. Proper management of OJ includes adequate water supply and electrolyte replacement, nutritional support, preventive antibiotics, pain relief, and itching relief. The surgical treatment of OJ depends on the cause, location, and severity of the obstruction. Biliary drainage, surgery, and endoscopic intervention are potential treatment options depending on the patient's condition. In addition to modern medical treatments, Traditional Chinese medicine may offer therapeutic benefits for OJ. A comprehensive search was conducted on PubMed for relevant articles published up to August 1970. This review discusses in detail the pathophysiological changes associated with OJ and presents effective strategies for managing the condition.

Pattern of bile cultures and antibiotic sensitivity tests in Sudanese patients diagnosed with obstructive jaundice: A single-center prospective study

Background and Aim

Biliary obstruction causes bacteriobilia and significant morbidity and high mortality, which necessitates prompt and effective treatment for a good clinical outcome. Hence, the aim of this study was to determine updated knowledge of biliary microbial spectrum, antibiotic sensitivity pattern, and key clinical factors of bacteriobilia.

Methods

This is a prospective study conducted during the period between November 2021 and December 2022 at Ibn Sina specialized hospital, Khartoum, Sudan, on 50 patients diagnosed with obstructive jaundice and symptomatic bacteriobilia who underwent open biliary surgeries electively. Bile samples were aspirated intra-operatively and cultured, and antibiotic sensitivity tests were performed.

Results

Fifty-four percent of patients diagnosed with obstructive jaundice who underwent elective open biliary surgeries were males with the ratio (2:1). Forty-six percent of patients were between 61 and 75 years (elderly). The most frequent cause of obstructive jaundice was migrating biliary stones (48% of cases). Thirty-two percent of patients were diabetic with bacteriobilia. The predominant isolated bacterial pathogen in this study was Escherichia coli (36% of cases). These biliary pathogens were sensitive to meropenem in 54% of cases and ciprofloxacin in 46%. Eventually, in all patients in this study, biliary bacterial pathogens were found to be resistant to a broad spectrum of antibiotics.

Conclusion

Careful selection of empirical antibiotic therapy based on surveillance of routine bile cultures during biliary tree procedures in patients with high risk of bacteriobilia will potentially help in improving the surgical outcomes and optimizing treatment of acute cholangitis, which is associated with high mortality.

Developmental Pharmacokinetics of Antibiotics Used in Neonatal ICU: Focus on Preterm Infants

Neonatal Infections are among the most common reasons for admission to the intensive care unit. Neonatal sepsis (NS) significantly contributes to mortality rates. Empiric antibiotic therapy of NS recommended by current international guidelines includes benzylpenicillin, ampicillin/amoxicillin, and aminoglycosides (gentamicin). The rise of antibacterial resistance precipitates the growth of the use of antibiotics of the Watch (second, third, and fourth generations of cephalosporines, carbapenems, macrolides, glycopeptides, rifamycins, fluoroquinolones) and Reserve groups (fifth generation of cephalosporines, oxazolidinones, lipoglycopeptides, fosfomycin), which are associated with a less clinical experience and higher risks of toxic reactions. A proper dosing regimen is essential for effective and safe antibiotic therapy, but its choice in neonates is complicated with high variability in the maturation of organ systems affecting drug absorption, distribution, metabolism, and excretion. Changes in antibiotic pharmacokinetic parameters result in altered efficacy and safety. Population pharmacokinetics can help to prognosis outcomes of antibiotic therapy, but it should be considered that the neonatal population is heterogeneous, and this heterogeneity is mainly determined by gestational and postnatal age. Preterm neonates are common in clinical practice, and due to the different physiology compared to the full terms, constitute a specific neonatal subpopulation. The objective of this review is to summarize the evidence about the developmental changes (specific for preterm and full-term infants, separately) of pharmacokinetic parameters of antibiotics used in neonatal intensive care units.

Pharmacokinetic and pharmacodynamic considerations of antibiotics and antifungals in liver transplantation recipients

The liver plays a major role in drug metabolism. Liver transplantation impacts the intrinsic metabolic capability and extrahepatic mechanisms of drug disposition and elimination. Different levels of inflammation and oxidative stress during transplantation, the process of liver regeneration, and the characteristics of the graft alter the amount of functional hepatocytes and activity of liver enzymes. Binding of drugs to plasma proteins is affected by the hyperbilirubinemia status and abnormal synthesis of albumin and alpha-1-acid glycoproteins. Postoperative intensive care complications such as biliary, circulatory, and cardiac also impact drug distribution. Renally eliminated antimicrobials commonly present reduced clearance due to hepatorenal syndrome and the use of nephrotoxic immunosuppressants. In addition, liver transplantation recipients are particularly susceptible to multidrug-resistant infections due to frequent manipulation, multiple hospitalizations, invasive devices, and frequent use of empiric broad-spectrum therapy. The selection of appropriate anti-infective therapy must consider the pathophysiological changes after transplantation that impact the pharmacokinetics and pharmacodynamics of antibiotics and antifungal drugs.

Enterococcus faecium Clade Competition in the Presence of β-Lactam Antibiotics in a Mouse GI Tract Colonization Model

Previously, we showed that Enterococcus faecium clade B strains outcompeted health care-associated clade A1 strains in murine gastrointestinal colonization. Here, parenterally administered piperacillin-tazobactam and ceftriaxone significantly promoted colonization by clade A1 over clade B strains except that ceftriaxone, at the dose used, did not favor the least β-lactam-resistant A1 strain. The advantage that β-lactam administration gives to more highly ampicillin-resistant E. faecium over ampicillin-susceptible strains mirrors what occurs in hospitalized patients administered these antibiotics.

Management of Symptomatic Gallstone Disease during COVID-19 Lockdown in a High-Resource Setting: Is There a Need for Treatment Alterations?

Introduction

Cholecystectomy (CCE) is the treatment of choice of symptomatic gallstones. Due to the SARS-CoV-2 pandemic, operating room (OR) capacities have been reduced. The goal of this study was to evaluate the duration of symptoms of patients presenting with gallstone disease during a lockdown, the surgical management, and the severity grade of their disease.

Materials and Methods

A cohort study of 353 CCEs performed at a university hospital over two 10-week periods during 2 pandemic lockdowns in Germany compared to corresponding periods in 2018 and 2019.

Results

During the lockdowns, 101 CCEs were performed compared to 252 in the prior years. The number of elective CCEs was reduced to save OR capacities (p < 0.001), and the most common indication for CCE was acute cholecystitis. The median time to CCE after symptom onset was 3 days in both groups for acute cholecystitis. The severity of cholecystitis was comparable (p = 0.760). The time to CCE after choledocholithiasis was shorter during the lockdowns (median of 4 days vs. 9 days; p = 0.006).

Conclusions

The incidence and severity of acute cholecystitis during the lockdowns were comparable to the prior years. Acute care surgery was provided at the expense of elective procedures, and there was no need for treatment alterations.

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.

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.

High incidence of postoperative infections after pancreaticoduodenectomy: A need for perioperative anti-infectious strategies

OBJECTIVES

Postoperative infections occur frequently after pancreaticoduodenectomy, especially in patients with bile colonization. Recommendations for perioperative anti-infectious treatment are lacking, and clinical practice is heterogenous. We have analyzed the effects of bile colonization and antibiotic prophylaxis on postoperative infection rates, types and therapeutic consequences.

METHODS

Retrospective observational study in patients undergoing pancreaticoduodenectomy with intraoperative bile culture. Data on postoperative infections and non-infectious complications, bile cultures and antibiotic prophylaxis adequacy to biliary bacteria were collected.

RESULTS

Among 129 patients, 53% had a positive bile culture and 23% had received appropriate antibiotic prophylaxis. Postoperative documented infection rate was over 40% in patients with or without bile colonization, but antibiotic therapy was more frequent in positive bile culture patients (77% vs. 57%, P=0,008). The median duration of antibiotic therapy was 11 days and included a broad-spectrum molecule in 42% of cases. Two-thirds of documented postoperative infections involved one or more bacteria isolated in bile cultures, which was associated with a higher complication rate. While bile culture yielded Gram-negative bacilli (57%) and Gram-positive cocci (43%), fungal microorganisms were scarce. Adequate preoperative antibiotic prophylaxis according to bile culture was not associated with reduced infectious or non-infectious complication rates.

CONCLUSION

Patients undergoing pancreaticoduodenectomy experience a high rate of postoperative infections, often involving bacteria from perioperative bile culture when positive, with no preventive effect of an adequate preoperative antibiotic prophylaxis. Increased postoperative complications in patients with bile colonization may render necessary a perioperative antibiotic treatment targeting bile microorganisms. Further prospective studies are needed to improve the anti-infectious strategy in these patients.