EVALUATION OF IMMUNE MARKERS AND INFLAMMATORY RESPONSES IN PATIENTS INFECTED WITH MULTIDRUG-RESISTANT BACTERIA

Abstract

Background: Multidrug-resistant (MDR) bacterial infections represent a growing global health concern due to limited therapeutic options, prolonged hospitalisation, and increased morbidity and mortality. The interaction between antimicrobial resistance and host immune-inflammatory responses remains an important area for improving diagnosis and patient management. Objective: This study aimed to identify the distribution of MDR bacterial pathogens and evaluate inflammatory and immune biomarkers associated with MDR infections, as well as assess their diagnostic performance using ROC curve analysis. Methods: A total of 100 patients with confirmed bacterial infections were enrolled in this study. Clinical samples were subjected to bacterial isolation, identification, and antimicrobial susceptibility testing according to standard microbiological procedures. MDR isolates were classified based on resistance patterns. Serum inflammatory and immune biomarkers, including C-reactive protein (CRP), procalcitonin (PCT), interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-α), interleukin-10 (IL-10), and neutrophil-to-lymphocyte ratio (NLR), were evaluated. Statistical analysis was performed to compare MDR and non-MDR groups, and ROC curve analysis was conducted to determine biomarker diagnostic accuracy. Results: Among the 100 bacterial isolates, 60% (n=60) were classified as MDR. Klebsiella pneumoniae was the predominant MDR pathogen (30%), followed by Acinetobacter baumannii (25%), Pseudomonas aeruginosa (18%), Escherichia coli (15%), and MRSA (12%). Bloodstream and respiratory tract infections were the most frequent infection sites among MDR cases. MDR isolates demonstrated the highest resistance rates among A. baumannii (86.4%), K. pneumoniae (66.7%), and P. aeruginosa (60%). Patients with MDR infections showed significantly elevated inflammatory markers compared with non-MDR patients, including CRP (142.6 ± 48.3 vs. 76.4 ± 31.5 mg/L), PCT (8.2 ± 3.6 vs. 3.1 ± 1.8 ng/mL), IL-6 (126.5 ± 42.7 vs. 62.8 ± 25.4 pg/mL), and TNF-α (48.3 ± 16.9 vs. 25.7 ± 11.2 pg/mL) (p < 0.001). NLR was also significantly higher in MDR cases (9.4 ± 4.1 vs. 5.2 ± 2.6; p < 0.001). ROC analysis revealed that PCT had the highest diagnostic performance (AUC=0.84, sensitivity 81%, specificity 78%), followed by IL-6 (AUC=0.81), CRP (AUC=0.78), TNF-α (AUC=0.76), and NLR (AUC=0.74). Conclusion: MDR bacterial infections were predominantly caused by Gram-negative pathogens, particularly K. pneumoniae and A. baumannii, and were associated with significant inflammatory activation and immune dysregulation. Procalcitonin and IL-6 showed the greatest potential as supportive biomarkers for early identification of MDR infections. Combining microbiological resistance profiling with inflammatory and immune biomarker assessment may improve early risk stratification and clinical management of patients with MDR bacterial infections.