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nicotine influence the kinetics of biofilm developmen

Should standardized susceptibility testing for microbial biofilms be introduced in clinical practice?

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up a NADH oxidase (NOX)-based assay to quantify the bactericidal activit

METHODS

Temocillin (6-�-methoxy ticarcillin) is well known for its resistance to degradation by �-lactamases including most ESBL. 1,2 It is therefor

Cellular pharmacokinetics and intracellular activity against Listeria monocytogenes and Staphylococcus aureus of chemically modified and nanoencapsulated gentamicin

OBJECTIVES: The aim of this study was to investigate different hydrophobic gentamicin formulations [gentamicin-bis(2-ethylhexyl) sulfosuccinate (GEN-AOT), microstructured GEN-AOT (PCA GEN-AOT) and GEN-AOT-loaded poly(lactide-co-glycolide) acid (PLGA) nanoparticles (NPs)] in view of improving its therapeutic index against intracellular bacteria. The intracellular accumulation, subcellular distribution and intracellular activity of GEN-AOT and NPs in different monocytic-macrophagic cell lines were studied. METHODS: Human THP-1 and murine J774 phagocytic cells were incubated with GEN-AOT formulations at relevant extracellular concentrations [from 1× MIC to 18 mg/L (human C(max))], and their intracellular accumulation, subcellular distribution and toxicity were evaluated and compared with those of conventional unmodified gentamicin. Intracellular activity of the formulations was determined against bacteria showing different subcellular localizations, namely Staphylococcus aureus (phagolysosomes) and Listeria monocytogenes (cytosol). RESULTS: GEN-AOT formulations accumulated 2-fold (GEN-AOT) to 8-fold (GEN-AOT NPs) more than gentamicin in phagocytic cells, with a predominant subcellular localization in the soluble fraction (cytosol) and with no significant cellular toxicity. NP formulations allowed gentamicin to exert its intracellular activity after shorter incubation times and/or at lower concentrations. With an extracellular concentration of 10× MIC, a 1 log(10) decrease in S. aureus intracellular inoculum was obtained after 12 h instead of 24 h for NPs versus free gentamicin, and a static effect was observed against L. monocytogenes at 24 h with NPs, while free gentamicin was ineffective. CONCLUSIONS: GEN-AOT formulations yielded a high cellular accumulation, especially in the cytosol, which resulted in improved efficacy against both intracellular S. aureus and L. monocytogenes

Artemisia Spp. Derivatives for COVID-19 Treatment: Anecdotal Use, Political Hype, Treatment Potential, Challenges, and Road Map to Randomized Clinical Trials

The world is currently facing a novel COVID-19 pandemic caused by SARS-CoV-2 that, as of July 12, 2020, has caused a reported 12,322,395 cases and 556,335 deaths. To date, only two treatments, remdesivir and dexamethasone, have demonstrated clinical efficacy through randomized controlled trials (RCTs) in seriously ill patients. The search for new or repurposed drugs for treatment of COVID-19 continues. We have witnessed anecdotal use of herbal medicines, including Artemisia spp. extracts, in low-income countries, and exaggerated claims of their efficacies that are not evidence based, with subsequent political controversy. These events highlight the urgent need for further research on herbal compounds to evaluate efficacy through RCTs, and, when efficacious compounds are identified, to establish the active ingredients, develop formulations and dosing, and define pharmacokinetics, toxicology, and safety to enable drug development. Derivatives from the herb Artemisia annua have been used as traditional medicine over centuries for the treatment of fevers, malaria, and respiratory tract infections. We review the bioactive compounds, pharmacological and immunological effects, and traditional uses for Artemisia spp. derivatives, and discuss the challenges and controversies surrounding current efforts and the scientific road map to advance them to prevent or treat COVID-19

Mechanisms of intrinsic resistance and acquired susceptibility of Pseudomonas aeruginosa isolated from cystic fibrosis patients to temocillin, a revived antibiotic

The β-lactam antibiotic temocillin (6-α-methoxy-ticarcillin) shows stability to most extended spectrum β-lactamases, but is considered inactive against Pseudomonas aeruginosa. Mutations in the MexAB-OprM efflux system, naturally occurring in cystic fibrosis (CF) isolates, have been previously shown to reverse this intrinsic resistance. In the present study, we measured temocillin activity in a large collection (n = 333) of P. aeruginosa CF isolates. 29% of the isolates had MICs ≤ 16 mg/L (proposed clinical breakpoint for temocillin). Mutations were observed in mexA or mexB in isolates for which temocillin MIC was ≤512 mg/L (nucleotide insertions or deletions, premature termination, tandem repeat, nonstop, and missense mutations). A correlation was observed between temocillin MICs and efflux rate of N-phenyl-1-naphthylamine (MexAB-OprM fluorescent substrate) and extracellular exopolysaccharide abundance (contributing to a mucoid phenotype). OpdK or OpdF anion-specific porins expression decreased temocillin MIC by ~1 two-fold dilution only. Contrarily to the common assumption that temocillin is inactive on P. aeruginosa, we show here clinically-exploitable MICs on a non-negligible proportion of CF isolates, explained by a wide diversity of mutations in mexA and/or mexB. In a broader context, this work contributes to increase our understanding of MexAB-OprM functionality and help delineating how antibiotics interact with MexA and MexB