Evaluation of the Effects of Carvacrol on Gram-Negative Bacilli Isolated from Wound Infections

Wound infections pose a significant challenge in modern medicine, driven by multimorbidity, weakened immunity, microbial virulence factors, and resistance to antibiotics and antiseptics. This study aims to evaluate the antibacterial properties of carvacrol (CAR), its impact on biofilm formation, and its capacity to trigger oxidative stress in clinical strains of Pseudomonas aeruginosa, Klebsiella pneumoniae, and Enterobacter cloacae. Carbapenemases in the studied bacteria were detected using culture on CarbaId agar. The presence of genes encoding bacterial virulence factors and carbapenemase production was confirmed using the PCR method. The antimicrobial activity of carvacrol was evaluated using the broth microdilution method. The ability of strains to form biofilm was determined using a modified crystal violet assay. Oxidative stress levels in bacterial cells in response to carvacrol treatment were measured using 2′,7′-dichlorofluorescein diacetate. Real-TimePCR was used to confirm the presence of NDM family carbapenemase genes in K. pneumoniae strains, KPC genes in E. cloacae strains, and VIM genes in P. aeruginosa strains. CAR exhibited a broad spectrum of antibacterial activity against the tested bacteria, with MIC values ranging from 125 to 1000 μg/mL. Treatment with 1/2 MIC of CAR did not significantly influence biofilm formation, except in a K. pneumoniae isolate. At 1/2 MIC, CAR induced an increase in intracellular ROS in most tested strains, with the exception of P. aeruginosa 25521221. This study provides insights into the antimicrobial efficacy of carvacrol against carbapenemase-producing pathogens isolated from wound infections—specifically P. aeruginosa, K. pneumoniae, and E. cloacae. CAR demonstrated promising bactericidal properties, likely mediated through the induction of oxidative stress, as evidenced by increased ROS generation in most studied isolates.