CLINICAL, EPIDEMIOLOGICAL AND MICROBIOLOGICAL PROFILES OF PATIENTS TREATED WITH COLISTIN AT TERTIARY CARE HOSPITALS IN PALESTINE

Abstract

Background: Antimicrobial resistance (AMR) constitutes a major worldwide public health problem in the 21st century. Colistin (polymyxin E) was re-introduced into clinical practice as a vital last-resort salvage agent against pan-drug-resistant and carbapenemase-producing Gram-negative pathogens. In Palestine, comprehensive studies regarding colistin use and resistance patterns are severely lacking due to the absence of a national surveillance system. This study aimed to evaluate the clinical, epidemiological, and microbiological profiles of patients treated with colistin in two major Palestinian tertiary care hospitals to construct essential baseline data for antimicrobial stewardship and infection control guidelines. Methods: A retrospective multi-center cross sectional study was conducted at An-Najah National University Hospital (ANNUH, Nablus) and The Istishari Arab Hospital (IAH, Ramallah) from 2021 to 2023. Total population sampling was applied to identify all adult inpatients (≥18 years) receiving intravenous colistin. Demographic information, underlying comorbidities, risk factors, ward distribution, admitting diagnoses, colistin dosing regimens, combination therapies, culture sources, isolated bacterial strains, antibiotic susceptibility patterns, and clinical outcomes (improvement versus in-hospital mortality) were systematically retrieved from electronic health records and analyzed using SPSS version 25. Results: A total of 867 patients (296 patients from ANNUH and 571 patients from IAH). The mean age of the patients was 52.16 years, while 588(67.82%) of them were males. Indwelling catheter use (62.1%) and central line use (36.3%) were the most prevalent risk factors. The majority of colistin utilization occurred in the intensive care unit (ICU) Department (36.2%). The most common admitting diagnosis was malignancy/cancer. Meropenem was the most common combined antibiotic (40.8%). In 57% of the cases, colistin was given as targeted therapy following the culture. Colistin was given intravenously in 100% of the cases; the most prescribed dose was 4.5 million units in 95.2% of the cases, every 24 hours (90.6%). Following the regimen, the outcome was measured, and 92.5% of the patients improved while 7.5% died. Among the 323 patients with positive microbiological cultures, Acinetobacter baumannii was the most frequently isolated organism (29.7%), followed by Stenotrophomonas maltophilia (24.1%), Klebsiella pneumoniae (23.5%), Escherichia coli (21.4%), and Pseudomonas aeruginosa (1.2%). Colistin susceptibility was highest among Klebsiella pneumoniae and Pseudomonas aeruginosa isolates (100%), followed by Escherichia coli (98.5%) and Acinetobacter baumannii (91.6%), whereas Stenotrophomonas maltophilia demonstrated the lowest susceptibility rate (70.7%). ICU admission, invasive device use (central venous catheters and mechanical ventilation), recent healthcare exposure (prior hospitalization, surgery, and antibiotic use), immunosuppression, underlying comorbidities (diabetes mellitus, cardiovascular disease, cancer, renal failure, respiratory disease, and COVID-19), bloodstream and urinary tract infections, and resistance to multiple antibiotics were all significantly linked to mortality. Conclusion: This study successfully constructs the first comprehensive baseline of colistin use, susceptibility, and outcomes in Palestinian tertiary hospitals. It emphasizes that colistin is still an indispensable last-line agent to defend bacteria; Because it achieved high overall clinical improvement rate with low in-hospital mortality. Colistin has high susceptibility across Enterobacterales and Acinetobacter, while S. maltophilia's resistance rate represents an alarming challenge. This makes colistin preservation a critical national priority in addition to empowered antimicrobial stewardship and infection control. To build on this work, further prospective studies with active drug monitoring, genomic surveillance, comparative efficacy trials are proposed.