Combating multidrug-resistant bacteria and associated virulence factors using Cichorium intybus extract: integrated microbiological characterization, phytochemical profiling, cytotoxicity assessment, and mechanistic insights

Abstract The global emergence of multidrug-resistant (MDR) Gram-negative pathogens necessitates novel therapeutic agents targeting bacterial growth and virulence. This study investigated the antibacterial, antibiofilm, antioxidant, cytotoxic, and apoptosis-inducing activities of Cichorium intybus leaf extract against MDR clinical isolates, alongside phytochemical profiling. Seventy-five clinical specimens were analyzed, predominantly blood (24%), sputum, pus, and urine (20% each), with stool samples underrepresented (4%; χ 2 (4) = 12.12, p = 0.033). A total of 75 bacterial isolates were identified using morphology, biochemical testing, and VITEK ® 2 (96–98% accuracy), including Klebsiella pneumoniae (56%), Escherichia coli (24%), and Acinetobacter baumannii (20%) (χ 2 (2) = 17.52, p < 0.001). The isolates exhibited high resistance to β-lactams, moderate resistance to aminoglycosides and tetracyclines, and greater susceptibility to imipenem and amikacin (χ 2 (3) = 92.4, p < 0.001). The C. intybus extract exhibited notable antibacterial activity, with the largest inhibition zone observed against K. pneumoniae (19.95 ± 2.16 mm). The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values ranged from 31.25 to 187.5 µg/mL and 62.5 to 375 µg/mL, respectively. Biofilm formation by A. baumannii , E. coli , and K. pneumoniae was significantly inhibited in a dose-dependent manner (0.78–50 µg/mL), with maximal suppression at 50 µg/m. Antioxidant assays demonstrated strong activity, with 92.2 ± 1.5% DPPH and 90.5 ± 2.0% ABTS inhibition at 1000 µg/mL, and IC 50 values of ~ 110 and ~ 115 µg/mL, respectively, showing strong correlation with ascorbic acid ( r = 0.997 and 0.995; p < 0.05). Cytotoxicity assays revealed selective, dose-dependent activity against PC3 and HepG2 cells compared with normal HFB4 cells (IC 50 = 24.6, 21.9, and 59.7 µg/mL, respectively), with apoptosis as the primary mechanism and minimal necrosis at lower doses. GC–MS and HPLC analyses identified bioactive compounds including chlorogenic, cichoric, linoleic, hexadecanoic, and octadecanoic acids, supporting synergistic antimicrobial, antioxidant, and anticancer effects. Overall, C. intybus demonstrates promising multifunctional bioactivity against MDR pathogens, supporting its potential as a natural therapeutic candidate.