Synergistic Activity of Indolicidin and Tigecycline Against Multidrug-Resistant Acinetobacter Baumannii Clinical Isolates.

Background/aims: Acinetobacter baumannii is a ubiquitous opportunistic microorganism associated with high morbidity and mortality Particularly among burn patients and immunocompromised individuals. This study aimed to assess the time-dependent antimicrobial effectiveness of indolicidin in combination with tigecycline against multidrug-resistant (MDR) A. baumannii isolates from patients with wound infections.

Methods: The antimicrobial synergy between indolicidin and tigecycline was evaluated using the checkerboard broth microdilution method And anti-biofilm activity was assessed using the crystal violet assay. Ten isolates resistant to multiple antibiotics were identified and confirmed using the API 20-NE system.

Results: Fractional inhibitory concentration (FIC) values ranged from 0.97 to 250 µg/ml. The results demonstrated that the inhibitory activity of indolicidin and tigecycline was significantly enhanced when combined With FIC values between 0.046 and 0.312 µg/ml. The MIC of indolicidin for isolate A4 decreased from 62.5 to 0.97 µg/ml • While the MIC of tigecycline decreased from 500 to 15.6 µg/ml • Indicating a strong synergistic effect. Additionally The combination therapy led to a 78% reduction in biofilm formation.

Conclusion: This study suggests a novel combination therapy for treating wound infections caused by MDR A. baumannii • Demonstrating significant efficacy in both bacterial inhibition and biofilm reduction.