In vivo antibacterial activity of Zataria multiflora Boiss extract and its components, carvacrol, and thymol, against colistin‐resistant Acinetobacter baumannii in a pneumonic BALB/c mouse model

Abstract

Background Acinetobacter baumannii has emerged as a major cause of nosocomial infections. Various resistance mechanisms of A. baumannii against antibiotics have transformed it into a successful nosocomial pathogen. Because of the limited number of available antibiotics, we used a medicinal plant with an antibacterial effect. Zataria multiflora Boiss (ZMB) extract and its components were used for the treatment of pneumonic mice infected with A. baumannii. The biological effects of this extract and the regulation of the outer membrane protein A (ompA) gene were used in a mouse model. Methods A pneumonic mouse model was prepared using clinical and standard strains (1.5 × 108 colony‐forming units/mL) of A. baumannii. BALB/c mice groups were treated with a ZMB extract, carvacrol, thymol, and sensitive antibiotics. The lung tissues of the treated mice were cultured for 5 days and each day, bacterial clearance and the ompA gene expression were assessed by quantitative real‐time polymerase chain reaction. Results In the lung tissue culture of pneumonic mice infected with standard or clinical isolate, no colony was detected when treated with the ZMB extract after 2 and 3 days (P < 0.01), respectively. In the carvacrol‐treated group, bacterial clearance was seen at day 4 and day 5 (P < 0.05). Bacterial clearance was seen 5 days after treatment with thymol and imipenem and 6 days after ampicillin/sulbactam treatment. The regulation of ompA gene was significantly decreased in this order: ZMB extract, carvacrol, thymol, imipenem, and ampicillin/sulbactam. Discussion The ZMB extract had a potent bactericidal effect against A. baumannii that could downregulate the ompA gene. ZBM extract and carvacrol could be novel therapeutic agents for antibiotic‐resistant A. baumannii.

Ethnobotany and the Role of Plant Natural Products in Antibiotic Drug Discovery

“…Twenty-one monoterpenoids were reported in our Review, among which ten exhibited high in vitro antibacterial activity. All of them were found in EOs from plants and have received much attention for their significant antibacterial activity, with four compounds (α-terpineol, carvacrol, eucalyptol, and thymol) being investigated with in vivo models of bacterial infections, ,− and six (α-pinene, carvacrol, eucalyptol, linalool, terpinen-4-ol, and thymol) tested in clinical trials (Table ) related to infectious and inflammatory conditions (e.g., gingivitis, sore throat, episiotomy, acute bronchitis, blepharitis). ,, Although highly active, these compounds present some drawbacks reducing their use as antibacterial agents, especially their unfavorable physicochemical profile with high volatility leading to instability and a short half-life, a low water solubility leading to a poor bioavailability after oral administration, an unpleasant taste and smell, and potential toxicity due to poor knowledge concerning the optimal safe dose to be administered. Future research directions include improvement of physicochemical properties, the examination of acute and chronic toxicity as well as teratogenicity, development of standardized formulations with multiple compounds, and realization of clinical trials focused on multidrug resistant bacterial infections.…”

Enhanced activity of Ellagic acid in lipid nanoparticles (EA-liposomes) against Acinetobacter baumannii in immunosuppressed mice

“…The use of natural compounds has been suggested to be a safe and effective therapeutic option to fight against drug-resistant A. baumannii ( Tsai et al, 2018 , Hassannejad et al, 2019 ). Natural compounds such as thymol and carvacrol showed antibacterial effects against drug-resistant A. baumannii ( Hassannejad et al, 2019 ). In another study, Tsai reported the activity of Scutellaria barbata against A. baumannii ( Tsai et al, 2018 ).…”

The Antimicrobial and Toxicity Influence of Six Carrier Oils on Essential Oil Compounds

“…This highlights the antimicrobial importance of these compounds, since they were able to maintain broad-spectrum, noteworthy antimicrobial activity across all the strains tested. Previous studies have also reported on the antimicrobial activities of carvacrol, cinnamaldehyde, isoeugenol, and thymol against several of the pathogens [35][36][37][38][39][40][41][42][43][44][45][46]. Phenolic compounds (carvacrol and thymol) could be…”