Antibacterial activity of traditional spices against lower respiratory tract pathogens: combinatorial effects of Trachyspermum ammi essential oil with conventional antibiotics.
Lett Appl Microbiol. 2018 Sep 06;:
Authors: Grădinaru AC, Trifan A, Şpac A, Brebu M, Miron A, Aprotosoaie AC
The aim of this study was to investigate the effects of ajowan essential oil/thymol and antibiotics combinations against three standard strains and six resistant clinical isolates of major respiratory bacteria (Pseudomonas aeruginosa, Staphylococcus aureus, Streptococcus pneumoniae). The broth microdilution method was conducted to determine the minimum inhibitory concentrations (MIC) of essential oil/thymol and antibiotics. The checkerboard method was used to investigate the interactions between the essential oil/thymol and antibiotics by means of the fractional inhibitory concentration index (FICI). The chemical composition of essential oil was also analyzed by GC-MS and GC-FID. Thymol (50.75%), γ-terpinene (25.94%) and p-cymene (18.31%) were identified as major constituents of the oil. The most sensitive organisms to ajowan volatile oil were Streptococcus pneumoniae bacteria (MIC=0.125-0.5 mg/mL). Synergistic effects were observed with ajowan essential oil/thymol and amoxicillin combinations on methicillin-resistant Staphylococcus aureus clinical isolates (FICI=0.37-0.50) and with essential oil and ciprofloxacin combinations against Pseudomonas aeruginosa ATCC 27853, Staphylococcus aureus ATCC 25923 and penicillin-resistant Streptococcus pneumoniae bacteria (FICI=0.37-0.50). Combination of thymol and ciprofloxacin produces synergistic effects only against Pseudomonas aeruginosa ATCC 27853 and penicillin resistant Streptococcus pneumoniae clinical isolate (FICI=0.46-0.49). This article is protected by copyright. All rights reserved.
PMID: 30187508 [PubMed - as supplied by publisher]