Antibacterial activity of Thymoquinone, an active principle of Nigella sativa and its potency to prevent bacterial biofilm formation

<p>Abstract</p> <p>Background</p> <p>Thymoquinone is an active principle of <it>Nigella sativa </it>seed known as "Habbah Al-Sauda" in Arabic countries and "Sinouj" in Tunisia. Bacterial biofilms tend to exhibit significant tolerance to antimicrobials drugs during infections.</p> <p>Methods</p> <p>The antibacterial activity of Thymoquinone (TQ) and its biofilm inhibition potencies were investigated on 11 human pathogenic bacteria. The growth and development of the biofilm were assessed using the crystal violet (CV) and the 2, 3-bis [2-methyloxy-4-nitro-5-sulfophenyl]-2H-tetrazolium-5-carboxanilide (XTT) reduction assay.</p> <p>Results</p> <p>TQ exhibited a significant bactericidal activity against the majority of the tested bacteria (MICs values ranged from 8 to 32 μg/ml) especially Gram positive cocci (<it>Staphylococcus aureus </it>ATCC 25923 and <it>Staphylococcus epidermidis </it>CIP 106510). Crystal violet assay demonstrated that the minimum biofilm inhibition concentration (BIC50) was reached with 22 and 60 μg/ml for <it>Staphylococcus aureus </it>ATCC 25923 and <it>Staphylococcus epidermidis </it>CIP 106510 respectively. In addition our data revealed that cells oxidative activity was influenced by TQ supplementation. In the same way, TQ prevented cell adhesion to glass slides surface.</p> <p>Conclusion</p> <p>The ability of TQ to prevent biofilm formation warrants further investigation to explore its use as bioactive substances with antibiofilm potential.</p

Detection of macrolide and disinfectant resistance genes in clinical Staphylococcus aureus and coagulase-negative staphylococci

<p>Abstract</p> <p>Background</p> <p><it>Staphylococcus aureus </it>and Coagulase-negative staphylococci (CoNS) are a major source of infections associated with indwelling medical devices. Many antiseptic agents are used in hygienic handwash to prevent nosocomial infections by Staphylococci. Our aim was to determine the antibiotic susceptibility and resistance to quaternary ammonium compound of 46 <it>S. aureus </it>strains and 71 CoNS.</p> <p>Methods</p> <p><it>S. aureus </it>(n = 46) isolated from auricular infection and CoNS (n = 71), 22 of the strains isolated from dialysis fluids and 49 of the strains isolated from needles cultures were investigated. Erythromycin resistance genes (<it>erm</it>A, <it>erm</it>B, <it>erm</it>C, <it>msr</it>A and <it>mef</it>) were analysed by multiplex PCR and disinfectant-resistant genes (<it>qac</it>A, <it>qac</it>B, and <it>qac</it>C) were studied by PCR-RFLP.</p> <p>Results</p> <p>The frequency of erythromycin resistance genes in <it>S. aureus </it>was: <it>erm</it>A+ 7.7%, <it>erm</it>B+ 13.7%, <it>erm</it>C+ 6% and <it>msr</it>A+ 10.2%. In addition, the number of positive isolates in CoNS was respectively <it>erm</it>A+ (9.4%), <it>erm</it>B+ (11.1%), <it>erm</it>C+ (27.4%), and <it>msr</it>A+ (41%). The MIC analyses revealed that 88 isolates (74%) were resistant to quaternary ammonium compound-based disinfectant benzalkonium chloride (BC). 56% of the BC-resistant staphylococcus isolates have at least one of the three resistant disinfectants genes (<it>qac</it>A, <it>qac</it>B and <it>qac</it>C). Nine strains (7.7%) among the CoNS species and two <it>S. aureus </it>strains (2%) harboured the three-<it>qac </it>genes. In addition, the <it>qac</it>C were detected in 41 strains.</p> <p>Conclusions</p> <p>Multi-resistant strains towards macrolide and disinfectant were recorded. The investigation of antibiotics and antiseptic-resistant CoNS may provide crucial information on the control of nosocomial infections.</p

Chemical composition, antimicrobial potential against cariogenic bacteria and cytotoxic activity of Tunisian Nigella sativa essential oil and thymoquinone

We investigate in this work the chemical composition by GC–EIMS, the antibacterial and the cytotoxic activities of Tunisian Nigella sativa essential oil and its bioactive compound, thymoquinone, were tested against various clinical cariogenic bacteria (n = 30). Eighty-four compounds were identified in the essential oil. The major one was p-cymene (49.48%) whereas thymoquinone represented only 0.79%. The essential oil (2.43 mg/disc) containing only 3.35 lg of thymoquinone showed pronounced dose dependant antibacterial activity against Streptococcus mitis, Streptococcus mutans, Streptococcus constellatus and Gemella haemolysans (15.5 ± 0.707 mm). However, pure thymoquinone compound (150 lg/disk) was active against all the studied strains especially S. mutans and S. mitis (24.5 ± 0.71 and 22 ± 1.41 mm inhibition zones, respectively). Their MIC values are representatives of a good effect. So, the essential oil strongest activity was seen against S. mitis, S. mutans, S. constellatus and G. haemolysans (MIC 2.13 mg/ml). However, thymoquinone was active against all the studied strains. The most important antibacterial activity was seen against S. constellatus (MIC 4 lg/ml). The growth inhibition effects of thymoquinone on human epithelial cell lines (Hep-2) were significantly stronger than the essential oil. The IC50 of thymoquinone and essential oil were 19.25 ± 1.6 and 55.2 ± 2.1 lg/ml, respectively. Our results demonstrate an important anticariogenic activity of the Tunisian N. sativa essential oil and thymoquinone. These effects further validate the traditional use of N. sativa in the folk medicine against various bacterial infections

Adiponectin expression and metabolic markers in obesity and Type 2 diabetes

International audienceBackground: Adiponectin has emerged over the last decade as a key adipokine linking obesity, insulin resistance, and Type 2 diabetes. However, the molecular mechanisms controlling adiponectin expression in adipose tissue are not fully elucidated. Furthermore, increasing evidence indicates that peroxisome proliferator-activated receptor-gamma (PPAR-gamma) plays an important, and beneficial, role in modulating adiponectin expression. Aim: The aim of the present study was to assess the separate role of obesity and Type 2 diabetes in the relationship between endogenous PPAR-gamma signaling and adiponectin expression in subcutaneous adipose tissue. Subjects and methods: Enzyme-linked immunosorbent assay and real time quantitative PCR analysis were carried out in overweight, obese, and/or diabetic Tunisian patients who underwent an abdominal surgery. Results: These results collectively indicate that circulating levels of adiponectin were decreased in all over-weight, obese, and/or diabetic (p<0.001). However, the subcutaneous mRNA expression of adiponectin was reduced only in diabetics (p<0.01) but presents some discrepancies in obese individuals. Moreover, mRNA levels of adiponectin were positively correlated with levels of mRNA encoding PPAR gamma and its heterodimeric partner retinoid X receptor-alpha (RXR-alpha), in both obese and diabetic patients. Conclusion: Our study on Tunisian patients shows impaired regulation of circulating and mRNA adiponectin levels dependent of metabolic disorders in obesity and Type 2 diabetes. The data suggest that subcutaneous adipose tissue may play an important role in modulating adiponectin expression in diabetes and obesity. Moreover, adiponectin mRNA could be potentially regulated by endogenous PPAR gamma/RXR alpha-dependent pathways. (J. Endocrinol. Invest. 34: e16-e23, 2011) (C) 2011, Editrice Kurti

What is the influence of tonsillectomy on the level of periodontal pathogens on the tongue dorsum and in periodontal pockets

Abstract Background For periodontal treatment, the full mouth disinfection approach suggests disinfection of oral soft tissues, such as tongue and tonsils concomitant to scaling and root planning since patients might benefit from treatment of these oral niches either. Periodontopathogenes in tonsillar tissue support this hypothesis. This prospective controlled clinical study investigated the change in the oral flora of patients who underwent tonsillectomy. Pockets were tested for eleven bacterial species before and six weeks after the surgical intervention. Methods Fifty generally healthy adults were included in this study. The test group consisted of 25 patients with tonsillectomy. The control group included 25 patients with otorhinolarynologic surgery without involvement of the oral cavity. Clinical parameters such as probing pocket depth, bleeding-on-probing index and plaque index were registered the evening before surgery. Also bacterial samples from the gingival sulcus and dorsum linguae were taken, and an additional sample from the removed tonsils in the test group. Six weeks after the intervention microbial samples of pockets and tongue were taken again. Data were tested for significant differences using Wilcoxon rank and Whitney-u-test. Results No relevant intra- or intergroup differences were found for the change of the eleven investigated species. Conclusion Based on the results of the present study, tonsillectomy does not seem to have an immediate relevant effect on the bacterial flora of tongue or periodontium. This study design was approved by the ethical committee of Zurich (KEK-ZH-Nr.2013–0419). Trial registration The trial was retrospectively registered in the German Clinical Trials Register (DRK00014077) on February 20, 2018