Background: There has been no unanimity concerning the ideal concentration of citric acid for safe use in clinical practice. This study evaluated the cytotoxicity and the antibacterial activity in ...infected dentinal tubules of 10% and 1% citric acid (CA) solutions. Methods: The cytotoxicity of CA solutions in DMEM (diluted 1/10, 1/100) was assessed in L-929 fibroblasts. A broth macrodilution method (MIC and MBC) was used to assess CA antibacterial concentration. The antimicrobial activity of CA solutions was also evaluated after their final rinse inside root canals in previously Enterococcus faecalis-contaminated dentinal tubules. Ten infected dentine samples were rinsed for 5 min with 5% NaOCl and subsequently with 1% citric acid for 3 min. Another 10 were rinsed with 5% NaOCl and 10% citric acid for 3 min; the remaining four specimens were utilized as positive controls. Two uncontaminated specimens were used as negative controls. After LIVE/DEAD BacLight staining, the samples were assessed using CLSM to analyze the percentage of residual live and dead cells. Results: Both undiluted and diluted CA solutions showed severe toxicity; no changes from normal morphology were displayed when diluted 1/100. The MIC and MBC of CA were 6.25 mg/mL and 12.50 mg/mL, respectively. CA solutions demonstrated significantly low levels of bacterial counts than the positive control group, reporting a value of 9.3% for the 10% solution versus the 1% solution (35.2%). Conclusions: Despite its valuable antimicrobial properties, the cytotoxic effects of citric acid should be considered during endodontic treatment.
The aim of this study was to evaluate the antimycobacterial activity of the
ethanolic extract
.
Ethanolic extract of
was set by maceration method. The broth microdilution and disc diffusion method ...were used to determine the minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC), respectively, of
ethanol extract on strain
H37Rv.
ethanol extract was found to have the antimycobacterial effects with a MIC value of 1600 μg/ml while MBC value of 3200 μg/ml for
H37Rv.
From these findings , it can be concluded that
a ethanol extract have an antibacterial activity against
s H37Rv
o and its potency elevated by increasing the
a ethanol extract concentration.
Pseudomonas aeruginosa is an opportunistic pathogen that produces sessile communities known as biofilms that are highly resistant to antibiotic treatment. Limited information is available on the ...exact role of various components of the matrix in biofilm-associated antibiotic resistance. Here we show that the presence of extracellular polysaccharide reduced the extent of biofilm-associated antibiotic resistance for one class of antibiotics. Minimal bactericidal concentration (MBC) for planktonic and biofilm cells of P. aeruginosa PA14 was measured using a 96 well microtiter plate assay. The MBC of biofilm-grown ΔpelA mutant, which does not produce the Pel polysaccharide, was 4-fold higher for tobramycin and gentamicin, and unchanged for ΔbifA mutant, which overproduces Pel, when compared to the wild type. Biofilms of pelA mutants in two clinical isolates of P. aeruginosa showed 4- and 8-fold higher MBC for tobramycin as compared to wild type. There was no difference in the biofilm resistance of any of these strains when tested with fluoroquinolones. This work forms a basis for future studies revealing the mechanisms of biofilm-associated antibiotic resistance to aminoglycoside antibiotics by P. aeruginosa.
Carnivorous plants—
Dionaea muscipula and
Drosera capensis contain two major groups of pharmaceutically important substances, naphthoquinones: plumbagin, ramentaceone and flavonoids: myricetin, ...quercetin, which are considered to be responsible, i.e. for antibacterial properties of preparations from their tissues. This study focused on increasing bactericidal activity of the extracts of
in vitro grown
D. muscipula and
D. capensis by stimulation of secondary metabolite synthesis by application of precursors of phenylpropanoid pathways (
l-phenylalanine or
trans-cinnamic acid) and elicitors: jasmonic acid, nitrogen deficiency, lysate of
Agrobacterim rhizogenes. HPLC analysis of plant extracts indicated that bacterial lysate was the most successful elicitor of naphthoquinones (2.6-fold increase over control for plumbagin and 1.9 for ramentaceone). The addition of
l-phenylalanine and nitrogen depletion caused the highest accumulation of quercetin (1.6–2 times the control) and myricetin (1.6–1.8 times the control), respectively. The minimal bactericidal concentrations (MBCs) of selected extracts and purified compounds (naphthoquinones and flavonoids) were estimated against hospital isolates of human pathogenic bacteria
. The lowest MBC values were observed for methanolic extract from
D. muscipula grown on medium with
l-phenylalanine (≤25–75
mg
FW
ml
−1). These results show the potential of Droseraceae plants grown
in vitro as a source of pharmaceutical material with valuable antimicrobial properties.
Citrullus colocynthis (Cucurbitaceae), a folk herbal medicine and traditionally used natural remedy for tuberculosis in India has been studied to validate its antitubercular activity against drug ...sensitive and drug resistant (including multidrug resistant) Mycobacterium tuberculosis and Mycobacterium other than tuberculosis (MOTT) bacilli.
Inhibitory and bactericidal activities of crude extracts, fractions and compounds of Citrullus colocynthis plant, consisting of aerial parts and ripe deseeded fruits were performed against the drug sensitive standard strain of Mycobacterium tuberculosis H37Rv (ATCC 27294), 16 drug resistant strains of Mycobacterium tuberculosis and two MOTT strains, using radiometric BACTEC 460TB system.
Methanolic extract of ripe deseeded fruit of Citrullus colocynthis has shown good activity (MIC≤62.5µg/ml), whereas among the bioactive fractions, FC IX demonstrated the best activity (MIC 31.2µg/ml) against Mycobacterium tuberculosis H37Rv. Bioactive FC III, IX and X also inhibited 16 clinical isolates of Mycobacterium tuberculosis consisting of seven non-multidrug resistants, eight multidrug resistants, one extensively drug resistant and two of MOTTs with MICs in the range of 50–125, 31.2–125 and 62.5–125µg/ml, respectively. Ursolic acid and cucurbitacin E 2-0-β-d-glucopyranoside were identified as the main biomarkers active against Mycobacterium tuberculosis H37Rv (MICs 50 and 25µg/ml respectively), as well as against the 18 clinical isolates. FC III and FC IX showed better inhibition of drug resistant and MOTT clinical isolates. Minimal bactericidal concentrations of extracts, fractions and compound C-2 were ≥two-fold MIC values.
The study provides a scientific rationale for the traditional use of Citrullus colocynthis fruit in the treatment of tuberculosis. In addition, the study elucidates a broad spectrum antimycobacterial action of Citrullus colocynthis fruit, which can contribute to the development of improved preparation of an antitubercular natural drug for the treatment of drug resistant tuberculosis and MOTT infection as well.
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•The study provides scientific rationale for the traditional use of Citrullus colocynthis in the treatment of tuberculosis in India.•Ursolic acid, cucurbitacin E 2-0-β-d-glucopyranoside and cucurbitacin I 2-0-β-d-glucopyranoside were isolated from Citrullus colocynthis.•The isolated compounds showed activity against drug sensitive, drug resistant, MDR and XDR Mycobacterium tuberculosis and two MOTT clinical isolates.•Bioactive fractions showed better antitubercular activity than the isolated compounds which may be due to the synergistic effect of the other constituents.
Aggregatibacter actinomycetemcomitans , a member of the Gram-negative taxonomic family Pasteurellaceae, has attracted considerable attention as a potentially important pathogen in specific forms of ...periodontal disease and has earned a reputation as a member of the HACEK group of bacteria associated with some cases of infective endocarditis. The bacterium has acquired an impressive virulence-related armamentarium, including two well-characterized cytotoxins, exoenzymes, adhesins, and signaling molecules that promote its colonization and the perturbation of the tissues, structural cells, and inflammatory cells of the human oral cavity. This Special Issue focuses on the properties and activities of A. actinomycetemcomitans that promote its function as an infectious agent, that is, its ability to target specific host populations and define its interactions with specific mucosal tissues and cells. The objective is to present a complete picture of the participation of this bacterium in disease by presenting both in vitro and in vivo experimental and clinical studies. A comprehensive view of the contribution of this bacterium to the mechanisms of infection and disease should also provide a basis for the development of new control strategies that move beyond the classical antibiotics.
In recent years, due to the growing phenomenon of antimicrobial resistance, the search for alternative strategies to antibiotic treatments is increasing and a considerable interest for the use of ...medical honey in clinical practice has emerged. Honey has been used for the treatment of skin lesions, in both humans and animals. However, knowledge concerning the use of medical honey in non‑traditional companion animals is scarce. The aim of this study was to assess the antibacterial activity of a standardized medical honey (Revamil, BFactory) against bacterial strains isolated from skin lesions of non‑traditional companion animals. The minimum bactericidal concentration (MBC) of Revamil honey against seventeen clinical isolates and three reference strains was established.The medical honey showed antimicrobial activity against both Gram‑positive and Gram‑negative bacteria. Growth was inhibited for all the strains at concentrations of medical honey ranging from 10 to 40%. Pseudomonas oryzihabitans and Alcaligenes faecalis showed the lowest MBC (10%). The reference strain Staphylococcus aureus ATCC25923 showed a higher sensitivity to 20% honey compare to the corresponding clinical isolate (P = 0.001). The observed results suggest that Revamil could represent an effective therapeutic aid, useful for the reduction of antibiotic use, in case of pathological skin infections in non‑traditional companion animals.
β-Phenylethylamine hydrochloride (PEA-HCl) and ethyl acetoacetate (EAA) are anti-microbials with applications in food processing. As food anti-microbials, the compounds will have to withstand the ...cooking process without changing to toxic compounds. With this Communication, we address the question of whether PEA and EAA are altered when heated to 73.9 °C or 93.3 °C. A combination of gas chromatography and mass spectrometry was used to analyze solutions of PEA(-HCl) or EAA in beef broth or water. In addition, the anti-microbial activity of PEA-HCl and EAA was compared between heated and unheated samples at a range of concentrations. The gas chromatograms of PEA(-HCl) and EAA showed one peak at early retention times that did not differ between the heated and unheated samples. The mass spectra for PEA and EAA were near identical to those from a spectral database and did not show any differences between the heated and unheated samples. We conclude that PEA(-HCl) and EAA formed pure solutions and were not altered during the heating process. In addition, the anti-microbial activity of PEA-HCl and EAA did not change after the heating of the compounds. Regardless of temperature, the minimal inhibitory concentrations (MICs) for PEA-HCl were 20.75 mmol mL
for
and
serotype Typhimurium. For EAA, the MICs were 23.4 mmol mL
for
and 15.6 mmol mL
for
.
Substituted salicylaldehydes are potent antibacterial and antifungal agents and may have chemotherapeutic potential. In the clinical setting, the minimal inhibitory concentration (MIC) as well as the ...minimal bactericidal and fungicidal concentrations (MBC and MFC, respectively) are of fundamental interest. Therefore, we have now, using a panel of fi ve microbial species (Bacillus cereus, Candida albicans, Escherichia coli, Saccharomyces cerevisiae, and Staphylococcus aureus), determined the MIC and MBC/MFC values of a total of 22 aromatic aldehydes, including 19 substituted salicylaldehydes and the unsubstituted parent compounds benzaldehyde and salicylaldehyde (2-hydroxybenzaldehyde). The results clearly indicate that both of the yeasts studied are remarkably sensitive to various salicylaldehydes and, especially, to halogenated ones. Some congeners clearly merit consideration as potential therapeutic agents for Candida infections. The MIC values of the most potent congeners are of roughly the same magnitude as that of amphotericin B, and the results of the MFC measurements indicate that the compounds are fungicidal. All of the bacteria studied are also sensitive to at least some of the compounds tested but, clearly, this class of antimicrobials has superior activity against yeasts. Structure-activity relationships are discussed for each microbial species and compared with each other. The comparison of the results of MIC and MBC/MFC measurements with those of agar diffusion tests revealed aspects that are of interest concerning the methodology of antimicrobial activity screening. Unexpectedly, it was found that some compounds that are completely devoid of activity in agar diffusion tests had potent activity in MIC tests, indicating that if only agar diffusion methodology is used in drug discovery, some highly active compounds may be missed
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