Background: Microbial colonization, biofilm formation, and the growing resistance of bacteria to traditional antibiotics make wound infections an important clinical problem. Disruption of the skin barrier provides an opportunity for pathogens to enter the tissue, which results in impaired healing and the formation of chronic wounds. Biofilm bacteria are also important in treating malfunction because they protect the microorganisms from host defenses and antimicrobial agents. Medicinal plants have attracted more and more attention as an alternative source of antimicrobial agents. Saussurea costus. It is an important medicinal plant that has been traditionally used to treat infections and inflammations. Its roots possess different phytochemicals, such as flavonoids, phenolic compounds, alkaloids and terpenoids , that are linked to antimicrobial and anti-inflammatory effects. This study aimed to investigate the antibacterial potential of S aussurea costus root extracts against bacteria causing wound infections and to evaluate their use as a natural agent or as an aid in wound healing. Materials and methods: 100 samples of wound infections were collected from patients with post-op infections, pressure ulcers, skin wounds and diabetic foot infections in the period of April 2025 to November 2025 from hospitals in Baghdad. Bacterial isolates were cultured on selective and differential media, and their identification was performed using colony morphology, Gram staining, biochemical assays, and the VITEK-2 system to confirm the results. Antibiotic susceptibility testing was conducted using Kirby-Bauer disc diffusion on Mueller-Hinton agar according to CLSI guidelines. Multidrug-resistant isolates were assessed for biofilm formation using microplate assays and Congo Red medium. Extracts of Saussurea Costus root were prepared using the ethanolic extraction method. Phytochemical analysis and HPLC analysis were performed to identify the biologically active compounds. The antibacterial activity of the plant extract was evaluated using microdilution to determine MIC and MBC values. Results: out of 100 wound infection samples, 55 bacterial isolates were obtained. Staphylococcus aureus accounted for 15 isolates (27.3%), and Pseudomonas aeruginosa accounted for 12 isolates (21.8%). Antibiotic susceptibility testing showed that All Staphylococcus aureus isolates (100%) exhibited resistance to oxacillin and cefoxitin. Resistance was observed in three isolates (33.3%) to tetracycline, rifampicin, and erythromycin. Two isolates (22.2%) showed resistance to fusidic acid and clindamycin, while two isolates (22.2%) were resistant to ciprofloxacin. One isolate (11.1%) demonstrated moderate susceptibility. Partial susceptibility was noted in six isolates (66.6%) to clindamycin and ciprofloxacin, and in six isolates (66.7%) to tetracycline, rifampicin, and erythromycin. All isolates remained fully sensitive (100%) to vancomycin, linezolid, tigecycline, and teicoplanin. The results of seven Pseudomonas aeruginosa isolates revealed variable resistance patterns. Resistance to gentamicin and aztreonam was observed in four isolates (57.1%), while resistance to levofloxacin and ciprofloxacin was detected in three isolates (42.9%). Resistance to meropenem, amikacin, piperacillin-tazobactam, cefepime, and ceftazidime was observed in two isolates (28.6%). Moderate sensitivity ranged between 14.3% and 28.6% for levofloxacin, amikacin, aztreonam, ciprofloxacin, piperacillin, cefepime, and tazobactam. Sensitivity of 57.1% was recorded in four isolates each for piperacillin-tazobactam, ceftazidime, piperacillin, and cefepime, while gentamicin showed sensitivity in three isolates (42.9%). Sensitivity of 42.8% was also observed in three isolates each for levofloxacin, meropenem, and imipenem The MIC for all Pseudomonas aeruginosa isolates was 125 µg/ml, while. the MIC for Staphylococcus aureus isolates ranged from 15.6 to 31.2 µg/ml. The MBC for all tested isolates was 250 µg/ml. This indicates that the MIC/MBC ratio has an inhibitory effect on Staphylococcus aureus growth and a bactericidal effect against Pseudomonas aeruginosa. Conclusion: This study highlights that extract from S aussurea Costus root exhibits potent antibacterial activity against multidrug-resistant and biofilm-forming bacteria, particularly Pseudomonas aeruginosa and Staphylococcus aureus, isolated from wound infections. The extract demonstrated strong inhibitory effects, evidenced by a decrease in the minimum inhibitory concentration (MIC) against Staphylococcus aureus, and exhibited bactericidal activity against Pseudomonas aeruginosa. These results suggest the potential use of plant-derived antimicrobial compounds as adjunctive or alternative agents for managing wound infections associated with multidrug-resistant and biofilm-forming bacteria.
