This study investigated the physicochemical properties of fir (Abies alba Mill.) honeydew honey (FHH) and its biological activity against the leading foodborne bacterium Campylobacter jejuni. ...Antibacterial activity, bacterial growth and anti-adhesion tests were performed in Mueller Hinton (MH) broth and cow’s milk used as a food model. FHH from the mountainous region of Croatia showed antibacterial activity against C. jejuni in MH broth and milk, with the minimal inhibitory concentration (MIC) values ranging from 12.5 to 50 mg/mL. A transmission electron microscopy (TEM) analysis of C. jejuni cells showed severe cellular damage after exposure to the tested honeydew honey. FHH in concentrations of 3 and 5% (w/v) inhibited growth and prevented adhesion to the polystyrene surface at a concentration of 25 mg/mL or lower of the bacterium C. jejuni in MH broth and milk. The anti-adhesion effect was more pronounced in the milk than in the MH broth. These results suggest that FHH has potent antibacterial activity against C. jejuni due to its particular physicochemical properties.
Cellulose fibers coated with a double-layer ZnO/Al2O3 thin film (cel/Al2O3/ZnO) were prepared in-situ by two successive processes of atomic layer deposition (ALD). Photoinactivation kinetics of ...Gram-negative (Escherichia coli) and Gram-positive (Staphylococcus aureus) bacteria were investigated in the dark and under UVA irradiation. Compared to the initial cellulose sample (cel) and cellulose coated with an Al2O3 thin film (cel/Al2O3), superior UVA photoinhibition was achieved for both bacteria treated with cel/Al2O3/ZnO within only 30 and 45 min of UVA irradiation for E. coli and S. aureus, respectively. FE-SEM and STEM micrographs showed strongly destructive effects on the morphology of both bacterial cell walls and the cytoplasmic membrane, which were attributed to the photogenerated reactive oxygen species (ROS). The kinetic data were successfully fitted using the modified Hom model, which consists of three rate constants describing the initial shoulder, rapid log-linear, and tail regions of the curves. As our results show, this cellulose-based material, further stabilized by the ALD Al2O3 interlayer, is promising for efficient photocatalytic disinfection of water.
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•ALD was implemented for surface coating of cellulose with a ZnO/Al2O3 bilayer.•Damage to the cell membrane of E. coli and S. aureus by UVA-generated ROS.•Inactivation kinetics follows the modified Hom model.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The group of nontuberculous mycobacteria (NTM) includes about 200 mycobacteria that are widespread in the natural environment as free-living saprophytic bacteria, commensals or symbionts. NTM, also ...referred to as atypical mycobacteria, are mostly apathogenic; nowadays, they are increasingly important environmental opportunistic pathogens. This study continues the work of previous studies which investigated the individual and synergistic effect of different essential oils (EOs) on NTM. The aim was to investigate the effect of the interaction of the common juniper (Juniperus communis) EO and the antimicrobials, amikacin, clarithromycin and rifampicin, against Mycobacterium avium and M. intracellulare using the checkerboard synergy method in an enriched Middlebrook 7H9 broth. Morphological changes of treated NTM cells were observed with a transmission electron microscope. The most synergistic combinations were found at subinhibitory concentrations of the common juniper EO and rifampicin against both tested NTM and this EO and clarithromycin against M. avium. A slightly smaller number of synergistic effects on both NTM were found using a combination of this EO and amikacin. Combinations of clarithromycin and the common juniper EO showed no synergism against M. intracellulare. The exposure of both NTM to synergistic combinations of this EO and antimicrobials caused significant morphological changes in mycobacterial cells. Synergism with the combined use of EOs and antimicrobials allows the use of low effective concentrations via the sustained antimicrobial effect of the tested substances, but with potentially reduced toxicity.
To explore the interaction effects of ciprofloxacin and ampicillin with nickel on the growth of bacteria,
Staphylococcus aureus
strain ATCC 29213,
Enterococcus faecalis
ATCC 29212 and
Escherichia ...coli
ATCC 25922 were used. Minimum inhibitory concentrations (MICs) were determined for nickel, ciprofloxacin and ampicillin, and the checkerboard method was used to assess their cumulative effects on bacterial growth. The interactions between the metal and antibiotics were assessed by the fractional inhibitory concentration (FIC). The MICs for ciprofloxacin and ampicillin were 0.31 and 1 mg/L for
E. faecalis
, 0.62 and 1 mg/L for
S. aureus
and 0.005 and 2.5 for
E. coli
, respectively. The MIC for nickel was 1000 mg/L for all bacteria. The FIC results for ciprofloxacin and nickel demonstrated an antagonistic effect of the two agents on the growth of
E. coli
and
E. faecalis
and an additive effect on
S. aureus
. The FICs for ampicillin and nickel demonstrated a synergistic effect on the growth of
E. faecalis
and
E. coli
. Different interactions of metals and antibiotics were observed depending on the bacteria and the type of antibiotic.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Legionella pneumophila is a Gram-negative bacterial pathogen that colonizes natural and artificial water systems and has the ability to form a biofilm. The biofilm protects L. pneumophila from ...various environmental factors and makes it more resistant to chlorine-based disinfectants. This study investigated the anti-bacterial properties of tea tree (Melaleuca alternifolia (Maiden and Betche) Cheel) oil and lemon eucalyptus tree (Eucalyptus citriodora Hook) essential oils (EOs) and their synergistic, additive inhibitory and anti-adhesive effects against L. pneumophila biofilm formation on polystyrene. The minimum effective concentration (MEC) for tea tree is 12.8 mg ml
−1
and for lemon eucalyptus tree EO 6.4 mg ml
−1
. In the checkerboard assay, different combinations of these two EO show synergistic and additive anti-microbial activity. The minimum anti-adhesive concentration (MAC) for tea tree is 12.8 mg ml
−1
and for lemon eucalyptus tree EO 6.4 mg ml
−1
. A combination of 3.2 mg ml
−1
tea tree EO and 0.8 mg ml
−1
lemon eucalyptus tree EO showed the strongest anti-adhesive effect against L. pneumophila on polystyrene. The tested oils and their combination showed intriguing potential to inhibit L. pneumophila biofilm formation.
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BFBNIB, GIS, IJS, KISLJ, NUK, PNG, UL, UM, UPUK
Zbog sve veće rezistencije bakterija na poznate antibiotike, u novije vrijeme provodi se niz istraživanja s ciljem pronalaženja prirodnih tvari, posebice biljaka, koje bi mogle pomoći u prevenciji i ...liječenju urinarnih infekcija koje se tretiraju antibioticima. Urinarne infekcije su upalne bolesti kojima su podložne sve dobne skupine i čine druge najčešće bakterijske infekcije kod ljudi. Češće se javljaju u žena i uglavnom ih uzrokuju gram negativne bakterije. Najčešći uzročnik je Escherichia coli. Uz liječenje antibioticima, često se koriste i pripravci ljekovitog bilja. Cilj rada je dati pregled istraživanja učinkovitosti zimzelene medvjetke, obične planike i brusnice u liječenju urinarnih infekcija.
is an emerging multidrug-resistant pathogen that can contaminate hospital surfaces in the form of a biofilm which is hard to remove with standard disinfectants. Because of biofilm resistance to ...conservative disinfectants, the application of new disinfection technologies is becoming more frequent. Ozone gas has antimicrobial activity but there is lack of data on its action against
biofilm. The aim of this study was to investigate the effects and mechanisms of action of gaseous ozone on the OXA-48-procuding
biofilm. A 24 h biofilm of
formed on ceramic tiles was subsequently exposed to different concentrations of ozone during one and two hours to determine the optimal ozone concentration. Afterwards, the total bacteria count, total biomass and oxidative stress levels were monitored. A total of 25 ppm of gaseous ozone was determined to be optimal ozone concentration and caused reduction in total bacteria number in all strains of
for 2.0 log
CFU/cm
, followed by reduction in total biomass up to 88.15%. Reactive oxygen species levels significantly increased after the ozone treatment at 182% for the representative
NCTC 13442 strain. Ozone gas in the concentration of 25 ppm caused significant biofilm reduction but did not completely eradicate the
biofilm formed on ceramics. In conclusion, ozone gas has great potential to be used as an additional hygiene measure in joint combat against biofilm in hospital environments.
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
for J. communis EO and 3.2 mg ml
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.
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