Browsing by Author "Teintze, Martin"

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18β-Glycyrrhetinic Acid Induces Metabolic Changes and Reduces Staphylococcus aureus Bacterial Cell-to-Cell Interactions
(MDPI AG, 2022-06) Weaver, Alan J.; Borgogna, Timothy R.; O’Shea-Stone, Galen; Peters, Tami R.; Copié, Valérie; Voyich, Jovanka; Teintze, Martin
The rise in bacterial resistance to common antibiotics has raised an increased need for alternative treatment strategies. The natural antibacterial product, 18β-glycyrrhetinic acid (GRA) has shown efficacy against community-associated methicillin-resistant Staphylococcus aureus (MRSA), although its interactions against planktonic and biofilm modes of growth remain poorly understood. This investigation utilized biochemical and metabolic approaches to further elucidate the effects of GRA on MRSA. Prolonged exposure of planktonic MRSA cell cultures to GRA resulted in increased production of staphyloxanthin, a pigment known to exhibit antioxidant and membrane-stabilizing functions. Then, 1D 1H NMR analyses of intracellular metabolite extracts from MRSA treated with GRA revealed significant changes in intracellular polar metabolite profiles, including increased levels of succinate and citrate, and significant reductions in several amino acids, including branch chain amino acids. These changes reflect the MRSA response to GRA exposure, including potentially altering its membrane composition, which consumes branched chain amino acids and leads to significant energy expenditure. Although GRA itself had no significant effect of biofilm viability, it seems to be an effective biofilm disruptor. This may be related to interference with cell–cell aggregation, as treatment of planktonic MRSA cultures with GRA leads to a significant reduction in micro-aggregation. The dispersive nature of GRA on MRSA biofilms may prove valuable for treatment of such infections and could be used to increase susceptibility to complementary antibiotic therapeutics.
Exposure of Methicillin-Resistant Staphylococcus aureus to Low Levels of the Antibacterial THAM-3ΦG Generates a Small Colony Drug-Resistant Phenotype
(2018-06) Weaver, Alan J.; Peters, Tami R.; Tripet, Brian P.; Van Vuren, Abigail; Rakesh; Lee, Richard E.; Copie, Valerie; Teintze, Martin
This study investigated resistance against trishexylaminomelamine trisphenylguanide (THAM-3ΦG), a novel antibacterial compound with selective microbicidal activity against Staphylococcus aureus. Resistance development was examined by culturing methicillin resistant S. aureus (MRSA) with sub-lethal doses of THAM-3ΦG. This quickly resulted in the formation of normal (WT) and small colonies (SC) of S. aureus exhibiting minimal inhibitory concentrations (MICs) 2× and 4× greater than the original MIC. Continuous cell passaging with increasing concentrations of THAM-3ΦG resulted in an exclusively SC phenotype with MIC >64 mg/L. Nuclear magnetic resonance (NMR)-based metabolomics and multivariate statistical analysis revealed three distinct metabolic profiles for THAM-3ΦG treated WT, untreated WT, and SC (both treated and untreated). The metabolome patterns of the SC sample groups match those reported for other small colony variants (SCV) of S. aureus. Supplementation of the SCV with menadione resulted in almost complete recovery of growth rate. This auxotrophism was corroborated by NMR analysis revealing the absence of menaquinone production in the SCV. In conclusion, MRSA rapidly acquires resistance to THAM-3ΦG through selection of a slow-growing menaquinone auxotroph. This study highlights the importance of evaluating and monitoring resistance to novel antibacterials during development.
Guanides as X4 HIV Inhibitors, Antibiotics and Inhibitors of Cancer Metastasis
(2013-03) Kelley, Amanda; Teintze, Martin
Guanide and biguanide compounds synthesized by the Teintze lab have been found to bind to the CXCR4 chemokine receptor which is used by X4 strains of HIV to enter cells and is involved in cancer metastasis. Therefore, they may be able to inhibit both HIV infection and cancer metastasis. When the chemokine SDF-1 binds the CXCR4 receptor, it activates an intracellular signal transduction pathway triggering chemotaxis of cancer cells, which will metastasize toward a gradient of SDF-1. It’s unknown whether the guanide compounds that bind CXCR4 activate the receptor which triggers the ERK MAPK1/3 pathway or are antagonists. For inhibiting either X4 HIV infection or cancer cell metastasis, the compounds should be antagonists. If they activated the receptor, they would cause inflammatory side effects or cell migration. To determine whether the compounds are antagonists, an ERK phosphorylation assay is being developed. CXCR4 over-expressing Cf2Th cells are grown in wells and treated with SDF-1 in the presence or absence of the guanide compounds. Duplicate western blots are run using the samples and probes with a monoclonal antibody to phosphorylated ERK and an antibody that recognizes all ERK, respectively. The chemiluminescence from the blots will be used to quantitatively determine whether the compounds are acting as antagonists or agonists.
Mechanism of Antibacterial Guanides Specifically Against MRSA USA300
(2013-03) Wright, Thomas; Teintze, Martin
New methods of treating bacterial infection are constantly needed as bacteria develop resistance to the present treatment options. Methicillin-resistant Staphylococcus aureus (MRSA) is an example of a pathogen that has become resistant to antibiotics such as penicillins, cephalosporins, and monolactams. The Teintze lab has synthesized many guanide, biguanide and phenylguanide compounds designed to block the CXCR4 chemokine receptor necessary for HIV to bind to mammalian cells. Some of these compounds also turned out to be active against various bacteria. Along with Staph, the lab has tested the compounds against Acinetobacter baumannii, Enterococcus faecalis, Escherichia coli, Burkholderia cepacia, and Pseudomonas aeruginosa. The compounds have some structural similarity to known bis-biguanides used as antibacterials (chlorhexidine and alexidine), but may inhibit bacterial growth by different mechanisms. The goal of this project has been to detemine the minimum inhibitory concentration (MIC) of THAM trisguanide and THAM trisphenylguanide on MRSA and investigate the changes in the proteome of treated cells to help elucidate the mechanism of action. The MIC allows reasonable comparison between the compounds and known antibacterial drugs. The proteins of treated and untreated bacteria are studied by 2D gel analysis, which separates proteins based on isoelectric point and size. The treated and untreated 2D gels were then compared and many differences were found.