Acute cholangitis is a serious and potentially life-threatening infection of the biliary tract that usually develops in the presence of biliary obstruction. It remains a major emergency in gastroenterology and hepatobiliary practice because delayed diagnosis and treatment can rapidly lead to sepsis, multiorgan dysfunction, and death. Although Charcot’s triad of fever, jaundice, and right upper quadrant abdominal pain is classically described, this presentation is not uniformly observed in all patients. Many individuals, particularly older adults, those with diabetes, and immunocompromised patients, may present with incomplete or atypical clinical features, which can delay recognition and definitive management [1,2]. The underlying pathophysiology of acute cholangitis involves biliary stasis and increased intraductal pressure secondary to obstruction, which promote bacterial colonization and facilitate the translocation of microorganisms and endotoxins into the bloodstream. The most common cause is choledocholithiasis, although malignant biliary obstruction, benign biliary strictures, postoperative biliary injury, and indwelling biliary stents are also important etiological factors. Over the past two decades, advances in abdominal ultrasonography, computed tomography, magnetic resonance cholangiopancreatography, and therapeutic endoscopy have improved diagnostic accuracy and treatment outcomes. Nevertheless, the disease continues to impose a substantial clinical burden, especially in tertiary care hospitals and in settings where patients present late in the course of illness [3,4]. From a microbiological perspective, acute cholangitis is most often caused by enteric Gram-negative bacilli, particularly Escherichia coli, Klebsiella species, and Enterobacter species. In some patients, Gram-positive cocci such as Enterococcus species and, less commonly, anaerobic organisms may also be isolated. The microbiological profile is clinically important because it directly influences antibiotic selection, treatment response, duration of hospitalization, and overall prognosis. In recent years, increasing resistance to commonly used antibiotics has emerged as a significant therapeutic challenge. The growing prevalence of extended-spectrum beta-lactamase [ESBL]-producing organisms and multidrug-resistant pathogens has reduced the effectiveness of empirical antibiotic regimens and may contribute to treatment failure, recurrent infection, prolonged hospital stay, and increased mortality [5,6]. The Tokyo Guidelines have brought greater uniformity to the diagnosis and management of acute cholangitis by offering standardized diagnostic criteria and severity grading. These guidelines emphasize the importance of early recognition, prompt initiation of antimicrobial therapy, hemodynamic stabilization, and timely biliary decompression, most commonly through endoscopic retrograde cholangiopancreatography [ERCP]. Severity stratification is especially valuable because it helps clinicians identify high-risk patients who require urgent intervention and intensive monitoring. Even so, considerable variation persists in clinical presentation, bacteriological pattern, resistance profile, and treatment outcomes across institutions and geographic regions, underscoring the need for local data to guide clinical decision-making [7,8]. Several studies have described the demographic features, etiological spectrum, and microbial isolates associated with acute cholangitis. However, data from tertiary care centers in developing regions remain limited, particularly regarding the relationship between microbiological findings, antimicrobial resistance, disease severity, and patient outcomes. Institution-specific evidence is necessary for refining empirical antibiotic policies, anticipating complications, improving biliary intervention strategies, and strengthening antimicrobial stewardship practices. A clearer understanding of these local trends would help optimize patient care and improve survival in this potentially fatal condition [9,10]. Rationale of the Study In view of the changing microbial profile of acute cholangitis and the increasing prevalence of antimicrobial resistance, there is a need to generate institution-specific data on its clinical presentation, causative organisms, and resistance patterns. Correlating these factors with disease severity, complications, recovery, and mortality can support more accurate risk stratification and more effective evidence-based management. The present study was therefore undertaken to address this knowledge gap in a tertiary care setting. The aim of the present study was to evaluate the clinical and microbiological profiles of patients with acute cholangitis and to assess their impact on clinical outcomes. The specific objectives were to examine the demographic and clinical characteristics of patients diagnosed with acute cholangitis, identify the microbiological spectrum and antimicrobial resistance patterns associated with the disease, assess disease severity using established criteria such as the Tokyo Guidelines, and evaluate clinical outcomes including recovery, complications, and mortality.

Study design and setting This prospective cohort study was conducted in the Department of General Medicine/Gastroenterology at KIMS and RF General Hospital, Amalapuram, Andhra Pradesh, India, over a period of one year from January 2024 to January 2025. The study was carried out in a tertiary care hospital setting to evaluate the clinical and microbiological profiles of patients presenting with acute cholangitis and to assess their impact on clinical outcomes. Study population The study included 88 consecutive patients diagnosed with acute cholangitis during the study period. Adult patients who fulfilled the clinical, laboratory, and radiological criteria for acute cholangitis were enrolled. Diagnosis and severity grading were assessed using established criteria, including the Tokyo Guidelines. Patients with incomplete clinical records, those unwilling to participate, or those in whom an alternative diagnosis was established were excluded from the study. Data collection After obtaining informed consent, detailed demographic and clinical information was recorded for all enrolled patients using a structured data collection proforma. Data collected included age, sex, presenting symptoms, comorbidities, etiological factors, physical examination findings, and duration of illness. Laboratory parameters such as complete blood count, liver function tests, renal function tests, inflammatory markers, and blood culture results were documented. Imaging findings from ultrasonography, computed tomography, magnetic resonance cholangiopancreatography, or other relevant modalities were also noted wherever available. Microbiological evaluation Blood and/or bile samples were collected under aseptic precautions before initiation of antibiotic therapy, whenever feasible. Samples were processed according to standard microbiological protocols for organism isolation and identification. Antimicrobial susceptibility testing was performed using standard laboratory methods, and resistance patterns, including extended-spectrum beta-lactamase production and multidrug resistance, were recorded. The microbiological spectrum and resistance profiles were analyzed in relation to severity of illness and treatment outcomes. Assessment of severity and management Disease severity was graded according to the Tokyo Guidelines into mild, moderate, and severe categories based on clinical, laboratory, and organ dysfunction parameters. Details regarding management, including antimicrobial therapy, supportive care, and biliary decompression procedures such as endoscopic retrograde cholangiopancreatography or other drainage interventions, were recorded. The timing and type of intervention were documented for outcome assessment. Outcome measures The primary outcome measures included recovery, development of complications, and in-hospital mortality. Secondary outcome measures included the association of microbiological isolates and antimicrobial resistance patterns with disease severity, requirement for biliary drainage, and adverse clinical outcomes. Statistical analysis The collected data were entered into Microsoft Excel and analyzed using IBM SPSS Statistics software. Continuous variables were expressed as mean ± standard deviation, while categorical variables were presented as frequency and percentage. Appropriate statistical tests were applied to determine associations between clinical variables, microbiological findings, resistance patterns, and outcomes. A p value of less than 0.05 was considered statistically significant. Ethical considerations The study was conducted after obtaining approval from the Institutional Ethics Committee of KIMS and RF General Hospital, Amalapuram, Andhra Pradesh, India. Written informed consent was obtained from all participants or their legally authorized representatives. Confidentiality of patient information was maintained throughout the study.

A total of 88 patients with acute cholangitis were included in this prospective cohort study conducted over one year (January 2024 to January 2025). Statistical analysis was performed using IBM SPSS Statistics. Continuous variables are expressed as mean ± standard deviation (SD), and categorical variables as frequencies and percentages. The mean age of the study population was 52.6 ± 15.4 years, with a male predominance (56.8%). The most common presenting features were fever (90.9%), abdominal pain (81.8%), and jaundice (68.2%), with Charcot’s triad present in 54.5% of patients. The most frequent etiology was choledocholithiasis (65.9%), followed by malignancy (20.5%) and benign biliary stricture (13.6%). Based on severity grading, 45.5% had moderate disease, while 20.4% presented with severe cholangitis. Table 1: Baseline Clinical Characteristics and Etiology (n = 88) Variable Frequency (n) Percentage (%) Age (mean ± SD) 52.6 ± 15.4 — Gender Male 50 56.8 Female 38 43.2 Clinical Features Fever 80 90.9 Abdominal pain 72 81.8 Jaundice 60 68.2 Charcot’s triad 48 54.5 Etiology Choledocholithiasis 58 65.9 Malignancy 18 20.5 Benign biliary stricture 12 13.6 Severity (Tokyo Guidelines) Mild (Grade I) 30 34.1 Moderate (Grade II) 40 45.5 Severe (Grade III) 18 20.4 Table 2: Microbiological Profile, Management, and Outcomes (n = 88) Variable Frequency (n) Percentage (%) Culture Results Positive culture 70 79.5 No growth 18 20.5 Organisms Isolated Escherichia coli 30 34.1 Klebsiella spp. 22 25.0 Enterococcus spp. 10 11.4 Pseudomonas spp. 8 9.1 Resistance Pattern ESBL producers 20 28.8 Multidrug-resistant organisms 16 18.2 Management ERCP 60 68.2 Percutaneous drainage 12 13.6 Conservative treatment 16 18.2 Outcomes Recovery 68 77.3 Complications 12 13.6 Mortality 8 9.1 Variable Frequency (n) Percentage (%) Microbiological cultures were positive in 79.5% of patients, with predominance of Gram-negative organisms, especially Escherichia coli (34.1%) and Klebsiella spp. (25.0%). Antimicrobial resistance analysis showed ESBL production in 28.8% and multidrug resistance in 18.2% of isolates. Endoscopic intervention (ERCP) was performed in 68.2% of cases. The overall recovery rate was 77.3%, while mortality was 9.1%. Severe disease and multidrug-resistant infections were significantly associated with poor outcomes (p < 0.05).

The present prospective cohort study provides a clinically relevant overview of acute cholangitis in a tertiary care setting, with emphasis on demographic profile, presenting features, etiology, microbiological spectrum, antimicrobial resistance, therapeutic intervention, and short-term outcomes. Overall, the findings reaffirm that acute cholangitis remains a significant biliary emergency in which the interaction between biliary obstruction, infection, and delayed source control determines prognosis. The study also adds important local evidence regarding resistant pathogens and their relationship with adverse outcomes. In the present cohort, the mean age was 52.6 years and there was a modest male predominance. This pattern is broadly consistent with earlier reports showing that acute cholangitis commonly affects middle-aged and older adults, in whom biliary stone disease, malignant obstruction, and associated comorbidities are more frequently encountered [11,12]. The male predominance observed in this study is also in agreement with some previous series, although sex distribution has varied across populations [13]. From a clinical standpoint, this age profile is important because advancing age is often associated with delayed presentation, higher disease severity, and greater vulnerability to septic complications. The clinical presentation in this study was dominated by fever, abdominal pain, and jaundice, while Charcot’s triad was present in just over half of the patients. This observation is comparable to classical and contemporary descriptions of acute cholangitis, in which the full triad is seen only in a proportion of cases [14]. Therefore, dependence on classical symptom complexes alone can lead to under-recognition of the disease. This has particular implications in elderly, diabetic, and immunocompromised patients, in whom symptoms can be muted or atypical. The occurrence of hypotension and altered sensorium in some patients in the present study further reflects progression to severe infection and systemic inflammatory response, emphasizing the need for early diagnosis and prompt escalation of care. With regard to etiology, choledocholithiasis was the most common underlying cause, followed by malignant obstruction and benign biliary strictures. This distribution is in line with existing literature, where biliary stones remain the leading precipitating factor for acute cholangitis [15,16]. The sizeable proportion of malignant obstruction in this cohort is clinically noteworthy. Patients with malignant biliary obstruction often have persistent obstruction, poor nutritional status, repeated instrumentation, and impaired host defenses, all of which can predispose to recurrent infection, resistant organisms, and worse outcomes. Thus, the etiological profile has both diagnostic and prognostic significance. The microbiological findings of the present study also mirror the established pathobiology of biliary infection. Culture positivity was high, and Gram-negative enteric bacilli, especially Escherichia coli and Klebsiella species, were the predominant isolates. These organisms are well recognized as major pathogens in acute cholangitis because biliary obstruction facilitates ascent and proliferation of gut-derived flora within the biliary tree [17,18]. The additional isolation of Enterococcus and Pseudomonas species suggests a broader bacteriological spectrum in a subset of patients, especially those with severe infection, previous antibiotic exposure, biliary interventions, or healthcare-associated risk factors. This observation supports the need to consider local epidemiology while selecting empirical therapy. A major finding of this study is the substantial prevalence of antimicrobial resistance. ESBL production and multidrug resistance were identified in a notable proportion of isolates, indicating that resistant biliary infections are no longer uncommon. This is consistent with the growing body of evidence showing increasing resistance among pathogens causing biliary tract infections [19,20]. The practical implication is significant: empirical regimens based solely on third-generation cephalosporins may be inadequate in a subset of patients, particularly those with severe illness or prior healthcare exposure. At the same time, indiscriminate escalation to broader agents is not an ideal solution, as it can further accelerate resistance selection. The present findings therefore support a balanced approach that combines early empirical coverage in high-risk patients with subsequent de-escalation based on culture and susceptibility results. Severity grading demonstrated that patients with severe cholangitis had poorer outcomes, including higher complication rates and mortality. This finding reinforces the clinical utility of standardized severity assessment systems such as the Tokyo Guidelines, which help identify patients requiring urgent biliary decompression, closer monitoring, and intensive supportive care [21]. Severity assessment should not be viewed as a purely classificatory exercise; rather, it is central to triaging patients and prioritizing intervention. In practical terms, patients with organ dysfunction, bacteremia, or resistant infections represent a high-risk subgroup that requires particularly aggressive and time-sensitive management. Endoscopic biliary drainage was performed in most patients and was associated with favorable outcomes, highlighting the central role of source control in acute cholangitis. This is in accordance with current therapeutic principles, which consider timely biliary decompression a cornerstone of treatment [22]. Antibiotics alone are often insufficient when biliary obstruction persists. ERCP addresses the underlying mechanical problem, lowers biliary pressure, improves drainage, and complements antimicrobial therapy. The better outcomes observed among patients who underwent timely drainage further underline the importance of early access to endoscopic services. In circumstances where ERCP is not immediately feasible, alternative drainage strategies may still be necessary to avoid deterioration. The mortality rate observed in this study lies within the range reported in previous literature [23]. Importantly, mortality was higher in patients with severe disease, multidrug-resistant infection, and positive blood cultures. These findings indicate that outcome is shaped by a combination of host status, infection burden, pathogen characteristics, and timeliness of intervention. Positive blood cultures in particular likely reflect systemic dissemination of infection and a higher likelihood of sepsis-related organ dysfunction. The observed association between bacteremia and poorer clinical course suggests that such patients should be managed with greater urgency and closer surveillance. The present study also has broader clinical implications. Because microbiological spectrum and resistance patterns vary across regions and institutions, local data are essential for building rational empirical antibiotic protocols. The findings support the need for periodic surveillance, preparation of institutional antibiograms, and integration of microbiological data into treatment algorithms. Such measures can improve antibiotic selection, reduce therapeutic failure, and strengthen antimicrobial stewardship in biliary infections. At the same time, certain limitations should be acknowledged. This was a single-center study, and the findings may not be fully generalizable to other institutions or populations. In addition, molecular characterization of resistant isolates and long-term follow-up after discharge were not undertaken. Larger multicentric studies incorporating detailed resistance mechanisms and extended outcome assessment would provide a more comprehensive understanding of the evolving epidemiology and prognostic determinants of acute cholangitis.

Acute cholangitis remains a major hepatobiliary emergency associated with substantial morbidity and measurable mortality. In the present study, choledocholithiasis was the predominant etiology, and Gram-negative enteric organisms, particularly Escherichia coli and Klebsiella species, formed the major microbiological profile. The burden of ESBL production and multidrug resistance was considerable and was associated with adverse clinical outcomes. Disease severity, bacteremia, and resistant infections emerged as important predictors of poor prognosis. These findings underscore the need for early diagnosis, prompt risk stratification, timely biliary decompression, and antibiotic therapy guided by local microbiological and susceptibility patterns. Continuous microbiological surveillance and strong antimicrobial stewardship are essential for improving outcomes and optimizing the management of acute cholangitis.

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