Evaluation of the antibacterial activity of Myrtus communis and glutaraldehyde against Pantoea agglomerans recovered from intensive care unit surfaces: A comparative in vitro study and molecular docking

Multidrug-resistant (MDR) bacteria in intensive care unit (ICU) environments pose an important infection-control challenge. This study investigated Myrtus communis as a potential plant-derived alternative to conventional disinfectants. To evaluate and compare the in vitro antibacterial activity of methanolic M. communis leaf extract and glutaraldehyde disinfectant (2.5%) against MDR Pantoea agglomerans (P. agglomerans) isolated from ICU inanimate surfaces and to characterize major phytochemical constituents associated with its activity. This study identified two P. agglomerans isolates by 16S rRNA gene sequencing. Methanolic M. communis leaf extract was prepared by cold maceration. Antibacterial activity was evaluated using agar well diffusion for the extract and agar disc diffusion for antibiotic references, while minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were determined by microdilution. GC-MS was used for phytochemical profiling, and molecular docking was performed to investigate predicted interactions of selected compounds with GroEL-KMgATP. The extract (100 mg/ml) produced a significantly larger inhibition zone (22.5 ± 0.9 mm) than 2.5% glutaraldehyde (9.3 ± 1.7 mm). The MIC and MBC of the extract were both 12.5 mg/ml. GC-MS identified quinic acid as the predominant constituent (40.02%), followed by 4H-pyran-4-one derivative (2.38%), bicyclo (2.2.1)heptan-2-ol, 1,5,5-trimethyl- (1.91%), and myrtenyl acetate (1.4%). Myrtenyl acetate showed the strongest predicted binding affinity to GroEL-KMgATP (- 6.2 kcal/mol). M. communis leaf extract demonstrated promising in vitro antibacterial activity against the tested MDR P. agglomerans and greater inhibition than glutaraldehyde under the conditions examined.