Synergistic potential of Juniperus communis and Helichrysum italicum essential oils against nontuberculous mycobacteria

• DOI: 10.1099/jmm.0.000962
• Publication Date: 2019-03-27T12:37:03Z
• Authors: Dolores Peruč; Brigita Tićac; Maja Abram; Dalibor Broznić; Sanja Štifter; Mladenka Malenica...; Ivana Gobin
• Keywords: nontuberculous mycobacteria; Helichrysum; 0301 basic medicine; antibiofilm; BIOMEDICINE AND HEALTHCARE. Basic Medical Sciences.; checkerboard synergy method; antiadhesion ; antibiofilm ; checkerboard synergy method ; essential oils ; nontuberculous mycobacteria, opportunistic premise plumbing pathogens; opportunistic premise plumbing pathogens; Drug Synergism; Nontuberculous Mycobacteria; Microbial Sensitivity Tests; Anti-Bacterial Agents; 03 medical and health sciences; BIOMEDICINE AND HEALTHCARE. Clinical Medical Sciences. Medical Microbiology.; Biofilms; Juniperus; Oils, Volatile; Humans; Plant Oils; BIOMEDICINA I ZDRAVSTVO. Temeljne medicinske znanosti.; essential oils; BIOMEDICINA I ZDRAVSTVO. Kliničke medicinske znanosti. Medicinska mikrobiologija.; antiadhesion; HeLa Cells

The present study evaluated the possible synergistic antimycobacterial interactions of Juniperus communis and Helichrysum italicum essential oils (EO).Antimycobacterial potential was tested against Mycobacterium avium and Mycobacterium intracellulare using broth and water dilution method and checkerboard synergy method. Antiadhesion and antibiofilm effect of EOs was evaluated on biotic (HeLa cells) and abiotic surface (polystyrene). To evaluate the possible mechanisms of action, cellular leakage of proteins and DNA was tested and structural changes were visualized with a transmission electron microscope.MIC, minimum bactericidal concentration (MBC) and minimal effective concentration (MEC) were 1.6 mg ml-1 for J. communis EO and 3.2 mg ml-1 for H. italicum EO against both mycobacteria. All combinations of EOs in checkerboard synergy method produced fractional inhibitory concentration index values ranging from 0.501 to 1.5, corresponding to synergistic, additive or indifferent effects. Mycobacterium avium showed a greater tendency to create biofilm but these EOs at subinhibitory concentrations (sMIC) effectively blocked the adhesion and the establishment of biofilm. The exposure of both mycobacteria to MICs and sMICs lead to significant morphological changes: acquired a swollen form, ghost-like cell, disorganized cytoplasm detached from the cell wall. OD value of supernatant for both mycobacteria exposed to EOs have confirmed that there is a leakage of cellular material.The leakage of the cellular material is noticeably higher in sMIC, which is probably due to cell wall damage. sMIC of both EOs have an additive or synergistic effect, reducing MICs, limiting adhesion and preventing the formation of biofilms.