Magnitude of ESKAPE Pathogens and Their Antimicrobial Resistance in a Tertiary Care Hospital

Volume 3 Issue 1 (Jul-Dec) 2025 Original Article (1) Articles in The ESRF Research Journal for Undergraduate Medical Students are Open Access articles published under a Creative Commons Attribution-Non Commercial 4.0 International License (CC BY-NC). This license permits use, distribution, and reproduction in any medium, provided the original work is properly cited, but it cannot be used for commercial purposes and it cannot be changed in any way. Published by: Eureka Scientech Research Foundation, Kolkata. Online access: https://esrfrjums.co.in Magnitude of ESKAPE Pathogens and Their Antimicrobial Resistance in a Tertiary Care Hospital Submission: 18th September,2025 Acceptance: 26th October, 2025 DOI:10.5281/ zenodo.17478020 Available from: https:// esrfrjums.co.in/index.php/main/ article/view/76 Chandrima Haldar,1 Debmalya Saha,1 Shuvojyoti Rakshit,2 Dip Mondal,2 Madhushree Masanta,2 Afsana Khatun,1 Somnath Bhunia.3 13rd Professional MBBS Part II Student, Nil Ratan Sircar Medical College, Kolkata 2Intern, Nil Ratan Sircar Medical College, Kolkata 3Assistant Professor, Department of Microbiology, Nil Ratan Sircar Medical College, Kolkata Abstract Background: Antimicrobial resistance (AMR) among healthcare-associated pathogens poses a critical global threat, with the ESKAPE group of organisms (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter species) being major contributors. Despite extensive global data, limited comparative studies across different wards is available. This study identifies this gap by observing the antibiotic sensitivity patterns of ESKAPE pathogens from the varied clinical samples collected from the critical and non-critical wards in the hospital. Methods: A cross-sectional descriptive study was conducted over six months in the Department of Microbiology, Nil Ratan Sircar Medical College and Hospital, Kolkata. Out of 2736 samples processed in the Microbiology department, 375 clinically significant ESKAPE pathogens from adult ICU, NICU, PICU, and adult non-ICU wards were analysed. Results: Incidence of ESKAPE pathogens are about 14%, among them Klebsiella pneumoniae was the most common isolate, predominantly from non-ICU sputum and urine samples, showing high sensitivity to gentamicin. Pseudomonas aeruginosa was frequent in ICU samples especially sputum samples, demonstrating high resistance to first line drugs and Pseudomonas isolated from non-ICU wards showed sensitivity to ciprofloxacin. Acinetobacter baumannii predominated in PICU and NICU. Enterococcus faecium and Staphylococcus isolates exhibited highest sensitivity to vancomycin. Conclusion: The study highlights the incidence of ESKAPE pathogens and their antibiogram. Wardspecific antibiograms are essential to optimize empirical therapy, reduce treatment failures, and improve patient outcomes. Regular surveillance and updated antimicrobial stewardship programs are crucial to combat evolving resistance trends. Corresponding Author Dr Somnath Bhunia Assistant Professor, Department of Microbiology NRS Medical College. Kolkata e-mail: [email protected] Keywords: Antimicrobial resistance, ESKAPE, resistant pathogens, clinical microbiology INTRODUCTION Antimicrobial resistance (AMR) poses a significant threat to medical science, contributing to rising mortality rates. According to infectious disease society of America (IDSA), the primary culprits behind healthcare-associated infections are the ESKAPE pathogens — Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter species — all known for their high propensity to develop resistance.1 They are capable of escaping the biocidal activity of antibiotics. Several studies have reported a marked increase in resistance to last-resort antibiotics such as polymyxin B, particularly in Indian hospitals.2,3 This crisis is further aggravated by the over-the-counter availability and widespread misuse of antibiotics without appropriate sensitivity testing.4 As a result, hospitalisation and mortality rates have surged, placing an increased burden on the healthcare system.5 Numerous global studies emphasize the critical nature of AMR, especially focusing on ESKAPE pathogens within hospital settings6,7. However, there is a noticeable gap in research from the post-COVID era, where resistance among hospital-acquired infections is expected to rise.8 Moreover, there is a scarcity of comparative studies across different hospital wards, an important perspective that could offer more clinically relevant Volume 3, Issue 1 (Jul-Dec), 2025 (2) Articles in The ESRF Research Journal for Undergraduate Medical Students are Open Access articles published under a Creative Commons Attribution-Non Commercial 4.0 International License (CC BY-NC). This license permits use, distribution, and reproduction in any medium, provided the original work is properly cited, but it cannot be used for commercial purposes and it cannot be changed in any way. insights into current trends in antimicrobial sensitivity, particularly (but not limited to) ESKAPE organisms.9 This study aims to address this gap by analysing the antimicrobial sensitivity patterns of ESKAPE pathogens from diverse clinical samples collected across critical and non-critical care units in a tertiary care hospital. The objective is to identify any significant shifts in resistance patterns that could guide the refinement of treatment protocols and improve patient outcomes. MATERIALS AND METHODS Study type and design: Descriptive Study with cross sectional design Study setting: Department of Microbiology, Nil Ratan Sircar Medical College and Hospital Study period: 6 months from August 2024 to January 2025. Study population: The study included patients of all age groups admitted to different hospital units, including adult and paediatric critical care units and general wards, who had submitted clinical samples for microbiological analysis. Inclusion criteria: • All clinically significant isolates belonging to ESKAPE pathogens obtained from patient samples during the study period • Samples with complete demographic and clinical details Exclusion criteria • Non-ESKAPE organisms • Contaminated or duplicate samples • Isolates with incomplete data or deemed clinically insignificant Sample size: Sample size was calculated using the formula for estimation of proportion Where, Z21-α/2 = critical value of the Normal distribution at α/2 p = proportion of ESKAPE pathogens in samples from a hospital d = margin of error Using p = 0.182 (based on the proportion of ESKAPE pathogens in samples from a hospital based on the study by Singh et al).10 1p=0.818, and d = 0.04, the calculated sample size is 372, rounded off to 375. So, the final sample size is 375. Sampling technique: Clinical samples were collected aseptically using standard protocol after proper consent and sent to Microbiology department for culture sensitivity testing. Samples were inoculated in routine culture media and incubated overnight. Culture plates showing growth were subjected to Gram stain and other biochemical tests for identification. Antimicrobial susceptibility testing (AST) was performed using the Kirby-Bauer disk diffusion method as per CLSI guidelines 2024. Some of the culture positive samples were put on automated VITEK system for identification and AST. Variables recorded included age, gender, ward/unit, sample type, bacterial species, and AST profile were collected from the records. This study was conducted after ethical clearance from institute ethic committee vide memo no NRSMC/IEC/250/2024 dated 18.7.2024. Data analysis: Laboratory data were entered into an electronic database and analyzed using SPSS v29 to determine distribution patterns and resistance trends across different wards and sample types. RESULTS The highest isolation rate was for Acinetobacter baumannii in NICU and PICU wards, reaching 100% of samples in both settings. In adult ICU, Pseudomonas aeruginosa predominated (91.3%), while Klebsiella pneumoniae (67.4%) was the most common in adult non-ICU. Other notable isolates included Enterococcus faecium (9.4%), Pseudomonas aeruginosa (10.5%), and Enterobacter spp. (4.9%) in adult non-ICU, indicating a wide range of resistant organisms even outside intensive care units. (Table 1) In adult ICU, sputum yielded Pseudomonas aeruginosa in 50% and Klebsiella pneumoniae in 4.3% of samples, with CSF and urine contributing smaller proportions. "Other" sample types accounted for 34.8% isolation of Pseudomonas aeruginosa. (Table 2) In adult non-ICU, the most frequent organism from sputum was Klebsiella pneumoniae (32.2%), and from urine, Klebsiella pneumoniae and Enterococcus faecium (both 3.8%). Blood cultures most often identified Staphylococcus aureus (1.9%) and MRSA (0.7%), highlighting the spectrum of resistance even within bloodstream infections. (Table 3) Antibiotic sensitivity percentages showed substantial resistance among gram-negatives. Acinetobacter baumannii showed notable sensitivity to colistin (78%), polymyxin B (82%), and moderate sensitivity to ampicillin-sulbactam (68%), but very low sensitivity to amikacin (26%) and ceftriaxone (4%). Pseudomonas aeruginosa remained sensitive to colistin (77%), polymyxin B (75%), and moderately to piperacillin-tazobactam (68%). Klebsiella pneumoniae showed sensitivity to colistin (71%), polymyxin B (69%), and moderate sensitivity to ampicillin-sulbactam, cefepime, and ceftazidime (58–60%) with poor sensitivity to tobramycin and ciprofloxacin (16–45%). (Table 4a) Enterococcus faecium displayed high sensitivity to vancomycin (78%) and linezolid (80%), as well as gentamicin (54% high-level resistance). Staphylococcus aureus isolates were most sensitive to linezolid (70%) and vancomycin (68%), with moderate sensitivity to erythromycin, clindamycin, and cotrimoxazole (65–70%). Sensitivity Original Article Magnitude of ESKAPE Pathogens and Their Antimicrobial Resistance Volume 3, Issue 1 (Jul-Dec), 2025 (3) Articles in The ESRF Research Journal for Undergraduate Medical Students are Open Access articles published under a Creative Commons Attribution-Non Commercial 4.0 International License (CC BY-NC). This license permits use, distribution, and reproduction in any medium, provided the original work is properly cited, but it cannot be used for commercial purposes and it cannot be changed in any way. to gentamicin, ampicillin, and tobramycin was relatively (12–32%). (Table 4b) DISCUSSION Out of 2736 samples that were sent for culture sensitivity, 679 (25%) samples showed significant growth, among them 375 (14%) were ESKAPE pathogens. It is about 55% of total culture positive isolates. One ominous finding from the adult ICU ward was the high isolation of Pseudomonas aeruginosa. It is a non‑fermenter bacteria and has the ability to form biofilms on frequently used medical devices like catheters and ventilators, leading to hospital‑acquired infections like catheter‑associated urinary tract infection (CAUTI) and ventilator‑associated pneumonia (VAP). Whereas in non-ICU, Klebsilla pneumoniae is the most common isolate. In PICU and NICU Acinetobacter baumannii is the most common isolated organism in various samples. Among the Gram-positive isolates Staphylococcus species were less in number and they showed a good percentage of sensitivity among the first line drugs. Antimicrobial resistance (AMR) remains a major global health crisis, particularly in hospital settings1,6. In this study, we examined the antimicrobial resistance profiles of common pathogens isolated from various wards. ward-specific variations in resistance patterns is also seen among the same isolate. The study revealed that Klebsiella pneumoniae was predominantly isolated from adult non-ICU samples mainly sputum and urine. Klebsiella pneumoniae isolated from sputum, blood, and urine showed high sensitivity to gentamicin, similar to findings by Herschel et al.11 and isolates from ICU were mostly sensitive to Meropenem. ICU-derived Klebsiella isolates highlight hospital-acquired UTI as a major concern. Enterobacter spp. was mainly isolated from sputum samples of adult non-ICU wards, with maximum sensitivity to minocycline, consistent with earlier surveillance reports.12 Enterococcus faecium, isolated from sputum and urine in adult nonICU wards, showed high sensitivity to Vancomycin. Its presence in sputum also suggests involvement in respiratory tract infections.13 Adult ICU wards showed a high prevalence of Pseudomonas aeruginosa, a non-fermenter known for causing hospital-acquired infections like CAUTI and VAP, owing to its biofilm-forming ability.14 Adult non-ICU wards also demonstrated significant involvement of this pathogen, especially from sputum samples. Isolates were sensitive to Ciprofloxacin but highly resistant to CLSI approved drugs. This altered sensitivity complicates treatment in ICU settings, severely limiting treatment options.15 In paediatric wards, especially PICU and NICU, Acinetobacter baumannii was abundantly isolated. The organism was fully sensitive to Polymyxin B however, ward-specific variation was noted. Such variation necessitates ward-specific protocols, especially for vulnerable groups like neonates.16 Staphylococcus aureus and CONS were prevalent in adult ICU and non-ICU wards, predominantly from blood samples. Isolates from non-ICU wards showed good sensitivity to all first-line antimicrobials listed in CLSI guidelines.17 Similarly, Staphylococcus species from sputum samples showed full sensitivity to firstline drugs suggesting these remain effective despite the organism’s HAI potential.18 Limitations of this study include the use of data from a single tertiary care hospital, which limits its generalizability. Additionally, not all organisms were tested against the same antibiotic panels, making cross-comparison challenging and less ideal for accurately pinpointing resistance patterns. CONCLUSION The study clearly demonstrates the presence of AMR patterns among bacterial isolates across various wards of a tertiary care hospital, with particularly high rates of multidrug resistance in ICUs. Ward-specific sensitivity differences underscore the need for targeted antimicrobial stewardship and localized treatment protocols. Developing ward and sample specific antibiograms can guide more effective empirical therapy, reducing hospital stays and improving bed turnover. Regular monitoring and updates of treatment strategies in response to evolving resistance trends are essential to reduce morbidity, mortality, transmission of resistant strains, and overall healthcare costs. ACKNOWLEDGMENTS The authors gratefully acknowledge the technical support provided by the Medical Technologists of the Department of Microbiology, Nil Ratan Sircar Medical College, during the course of this study. CONFLICT OF INTEREST None Declared FUNDING The authors received no financial support for the research, authorship, and/or publication of this article. Original Article Magnitude of ESKAPE Pathogens and Their Antimicrobial Resistance Volume 3, Issue 1 (Jul-Dec), 2025 (4) Articles in The ESRF Research Journal for Undergraduate Medical Students are Open Access articles published under a Creative Commons Attribution-Non Commercial 4.0 International License (CC BY-NC). This license permits use, distribution, and reproduction in any medium, provided the original work is properly cited, but it cannot be used for commercial purposes and it cannot be changed in any way. Table 1: Ward wise distribution of isolated ESKAPE organisms (n=375) Table 2: Sample wise distribution of isolated ESKAPE organisms in adult ICU (n=46) Original Article Magnitude of ESKAPE Pathogens and Their Antimicrobial Resistance WARD ESKAPE ORGANISM ISOLATED FROM PATIENT SAMPLES NO. OF SAMPLES n (%) Adult ICU (n=46) Klebsiella pneumoniae 3 (6.5) Pseudomonas aeruginosa 42 (91.3) Staphylococcus aureus 1 (2.2) Adult non-ICU (n=267) Acinetobacter baumannii 5 (1.9) Enterobacter sp 13 (4.9) Enterococcus faecium 25 (9.4) Klebsiella pneumoniae 180 (67.4) Pseudomonas aeruginosa 28 (10.5) Staphylococcus aureus 16 (6.0) NICU (n=24) Acinetobacter baumannii 24 (100) PICU (n=38) Acinetobacter baumannii 38 (100) Sample ESKAPE Organism isolated from patient samples No of samples n (%) CSF Pseudomonas aeruginosa 2(4.3) SPUTUM Klebsiella pneumoniae 2(4.3) Pseudomonas aeruginosa 23 (50) URINE Klebsiella pneumoniae 1(2.2) Pseudomonas aeruginosa 1(2.2) OTHERS Pseudomonas aeruginosa 16 (34.8) Staphylococcus aureus 1(2.2) Total 46 (100) Volume 3, Issue 1 (Jul-Dec), 2025 (5) Articles in The ESRF Research Journal for Undergraduate Medical Students are Open Access articles published under a Creative Commons Attribution-Non Commercial 4.0 International License (CC BY-NC). This license permits use, distribution, and reproduction in any medium, provided the original work is properly cited, but it cannot be used for commercial purposes and it cannot be changed in any way. Table 3: Sample wise distribution of isolated ESKAPE organisms in ADULT NON-ICU (n=267) Original Article Magnitude of ESKAPE Pathogens and Their Antimicrobial Resistance SAMPLES ESKAPE ORGANISM ISOLATED FROM PATIENT SAMPLES NO. OF SAMPLES n (%) SPUTUM Acinetobacter baumannii 9 (3.4) Enterobacter sp 6 (2.2) Enterococcus faecium 4 (1.5) Klebsiella pneumoniae 86 (32.2) Pseudomonas aeruginosa 21 (7.9) BLOOD Staphylococcus aureus 5 (1.9) Staphylococcus aureus MRSA 2 (0.7) URINE Enterobacter sp 2 (0.7) Enterococcus faecium 9(3.4) Klebsiella pneumoniae 9(3.4) OTHERS Acinetobacter baumannii 3 (1.1) Enterobacter sp 3 (1.1) Enterococcus faecium 12 (4.5) Klebsiella pneumoniae 80 (29.9) Pseudomonas aeruginosa 7 (2.6) Staphylococcus aureus 3 (1.1) Staphylococcus aureus MRSA 5 (1.9) Staphylococcus aureus MSSA 1 (0.4) Total 267 (100) Volume 3, Issue 1 (Jul-Dec), 2025 (6) Articles in The ESRF Research Journal for Undergraduate Medical Students are Open Access articles published under a Creative Commons Attribution-Non Commercial 4.0 International License (CC BY-NC). This license permits use, distribution, and reproduction in any medium, provided the original work is properly cited, but it cannot be used for commercial purposes and it cannot be changed in any way. Table 4a: Antibiotic sensitivity percentage (%) of Gram negative ESKAPE pathogens Table 4b: Antibiotic sensitivity percentage (%) of Gram positive ESKAPE pathogens Original Article Magnitude of ESKAPE Pathogens and Their Antimicrobial Resistance Organism AmpSalbact Pipertazob Cefepime Ceftazidi me Meropenem Ciprofloxacin Tobramycin Amikacin Colistin Gentamicin PolymyxinB Aztreonam Ceftriaxone A.baumannii 68 67 69 71 64 16 10 26 78 27 82 57 4 P.aeruginosa 64 68 66 67 63 66 15 35 77 36 75 55 21 K.pneumoniae 58 59 60 57 62 45 16 36 71 58 69 52 57 Organism Ampicillin Vancomycin Erythromycin Clindamycin Ciprofloxacin Tobramycin Linezolid Gentamicin Cotrimoxazole S.aureus 21 68 66 65 44 12 70 32 70 Enterococcus faecium 52 78 - - - - 80 54(high level) - Volume 3, Issue 1 (Jul-Dec), 2025 (7) Articles in The ESRF Research Journal for Undergraduate Medical Students are Open Access articles published under a Creative Commons Attribution-Non Commercial 4.0 International License (CC BY-NC). 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J Antimicrob Chemother. 2009;64(3):441–446. 18. Chambers HF, Deleo FR. Waves of resistance: Staphylococcus aureus in the antibiotic era. Nat Rev Microbiol. 2009;7(9):629– 641. Original Article Magnitude of ESKAPE Pathogens and Their Antimicrobial Resistance Volume 3, Issue 1 (Jul-Dec), 2025 (8) Articles in The ESRF Research Journal for Undergraduate Medical Students are Open Access articles published under a Creative Commons Attribution-Non Commercial 4.0 International License (CC BY-NC). This license permits use, distribution, and reproduction in any medium, provided the original work is properly cited, but it cannot be used for commercial purposes and it cannot be changed in any way. INTENTIONALLY LEFT BLANK Original Article Magnitude of ESKAPE Pathogens and Their Antimicrobial Resistance