Impact of the Order of Initiation of Fluconazole and Amphotericin B in Sequential or Combination Therapy on Killing of Candida albicans In Vitro and in a Rabbit Model of Endocarditis and Pyelonephritis

ABSTRACT In vitro time-kill studies and a rabbit model of endocarditis and pyelonephritis were used to define the impact that the order of exposure of Candida albicans to fluconazole (FLC) and amphotericin B (AMB), as sequential and combination therapies, had on the susceptibility of C. albicans to AMB and on the outcome. The contribution of FLC-induced resistance to AMB for C. albicans also was assessed. In vitro, AMB monotherapy rapidly killed each of four C. albicans strains; FLC alone was fungistatic. Preincubation of these fungi with FLC for 18 h prior to exposure to AMB decreased their susceptibilities to AMB for 8 to >40 h. Induced resistance to AMB was transient, but the duration of resistance increased with the length of FLC preincubation. Yeast sequentially incubated with FLC followed by AMB plus FLC (FLC→AMB+FLC) showed fungistatic growth kinetics similar to that of fungi that were exposed to FLC alone. This antagonistic effect persisted for at least 24 h. Simultaneous exposure of C. albicans to AMB and FLC [AMB+FLC(simult)] demonstrated activity similar to that with AMB alone for AMB concentrations of ≥1 μg/ml; antagonism was seen using an AMB concentration of 0.5 μg/ml. The in vitro findings accurately predicted outcomes in our rabbit infection model. In vivo, AMB monotherapy and treatment with AMB for 24 h followed by AMB plus FLC (AMB→AMB+FLC) rapidly sterilized kidneys and cardiac vegetations. AMB+FLC(simult) and FLC→AMB treatments were slower in clearing fungi from infected tissues. FLC monotherapy and FLC→AMB+FLC were both fungistatic and were the least active regimens. No adverse interaction was observed between AMB and FLC for the AMB→FLC regimen. However, FLC→AMB treatment was slower than AMB alone in clearing fungi from tissues. Thus, our in vitro and in vivo studies both demonstrate that preexposure of C. albicans to FLC reduces fungal susceptibility to AMB. The length of FLC preexposure and whether AMB is subsequently used alone or in combination with FLC determine the duration of induced resistance to AMB.

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Antifungal efficacy of isavuconazole and liposomal amphotericin B in a rabbit model of Exserohilum rostratum meningoencephalitis: A preclinical paradigm for management of CNS phaeohyphomycosis

Medical Mycology ◽

10.1093/mmy/myaa102 ◽

2020 ◽

Author(s):

Vidmantas Petraitis ◽

Ruta Petraitiene ◽

Aspasia Katragkou ◽

Bo Bo Win Maung ◽

Patriss W Moradi ◽

...

Keyword(s):

Amphotericin B ◽

Liposomal Amphotericin ◽

Rabbit Model ◽

In Vivo Studies ◽

Liposomal Amphotericin B ◽

Mortality And Morbidity ◽

Amphotericin B Deoxycholate ◽

Exserohilum Rostratum

Abstract Treatment options for Exserohilum rostratum meningoencephalitis and other causes of phaeohyphomycosis of the central nervous system (CNS) are limited, while mortality and morbidity remain high. We therefore evaluated isavuconazole, a new antifungal triazole in comparison to liposomal amphotericin B (LAMB), in vitro and in the rabbit model of Exserohilum rostratum meningoencephalitis. We hypothesized that isavuconazole alone or in combination with LAMB or micafungin may be alternative options for treatment of CNS phaeohyphomycosis. We therefore investigated the in vitro antifungal activity of isavuconazole alone or in combination with amphotericin B deoxycholate (DAMB) or micafungin and efficacy of treatment with isavuconazole and LAMB in a rabbit model of experimental E. rostratum meningoencephalitis. Combination checkerboard plates were used to determine the minimum inhibitory concentrations, minimal lethal concentrations, fractional inhibitory concentration indices, and Bliss surface analysis of isavuconazole and amphotericin B deoxycholate (DAMB), either alone or in combination. As there were no in vitro synergistic or antagonistic interactions for either combination of antifungal agents against the E. rostratum isolates, in vivo studies were conducted with isavuconazole and LAMB as monotherapies. Rabbits were divided in following groups: treated with isavuconazole at 60 mg/kg/d (ISAV60), LAMB at 5.0 (LAMB5), 7.5 (LAMB7.5), and 10 mg/kg/d (LAMB10), and untreated controls (UC). In ISAV60-, LAMB5-, LAMB7.5-, and LAMB10-treated rabbits, significant reductions of fungal burden of E. rostratum in cerebral, cerebellar, and spinal cord tissues (P < 0.01) were demonstrated in comparison to those of UC. These antifungal effects correlated with significant reduction of CSF (1→3)-β-D-glucan levels vs UC (P < 0.05). These data establish new translational insights into treatment of CNS phaeohyphomycosis.

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Candida albicans Morphology-Dependent Host FGF-2 Response as a Potential Therapeutic Target

Journal of Fungi ◽

10.3390/jof5010022 ◽

2019 ◽

Vol 5 (1) ◽

pp. 22 ◽

Cited By ~ 3

Author(s):

Sandeep Vellanki ◽

Eun Huh ◽

Stephen Saville ◽

Soo Lee

Keyword(s):

Candida Albicans ◽

Growth Factor ◽

Underlying Mechanism ◽

Yeast Cells ◽

In Vivo Studies ◽

Infection Model ◽

Physiological Processes ◽

Microbial Infections

Angiogenesis mediated by proteins such as Fibroblast Growth Factor-2 (FGF-2) is a vital component of normal physiological processes and has also been implicated in contributing to the disease state associated with various microbial infections. Previous studies by our group and others have shown that Candida albicans, a common agent of candidiasis, induces FGF-2 secretion in vitro and angiogenesis in brains and kidneys during systemic infections. However, the underlying mechanism(s) via which the fungus increases FGF-2 production and the role(s) that FGF-2/angiogenesis plays in C. albicans disease remain unknown. Here we show, for the first time, that C. albicans hyphae (and not yeast cells) increase the FGF-2 response in human endothelial cells. Moreover, Candidalysin, a toxin secreted exclusively by C. albicans in the hyphal state, is required to induce this response. Our in vivo studies show that in the systemic C. albicans infection model, mice treated with FGF-2 exhibit significantly higher mortality rates when compared to untreated mice not given the angiogenic growth factor. Even treatment with fluconazole could not fully rescue infected animals that were administered FGF-2. Our data suggest that the increase of FGF-2 production/angiogenesis induced by Candidalysin contributes to the pathogenicity of C. albicans.

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Comparison of a Rabbit Model of Bacterial Endocarditis and an In Vitro Infection Model with Simulated Endocardial Vegetations

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.44.7.1921-1924.2000 ◽

2000 ◽

Vol 44 (7) ◽

pp. 1921-1924 ◽

Cited By ~ 22

Author(s):

Ellie Hershberger ◽

Elizabeth A. Coyle ◽

Glenn W. Kaatz ◽

Marcus J. Zervos ◽

Michael J. Rybak

Keyword(s):

In Vitro Model ◽

Antimicrobial Agents ◽

Rabbit Model ◽

In Vitro Models ◽

Bacterial Endocarditis ◽

In Vivo Studies ◽

Infection Model ◽

Vitro Model

ABSTRACT Animal models are commonly used to determine the efficacy of various antimicrobial agents for treatment of bacterial endocarditis. Previously we have utilized an in vitro infection model, which incorporates simulated endocardial vegetations (SEVs) to evaluate the pharmacodynamics of various antibiotics. In the present study, we compared four experimental rabbit endocarditis protocols to an in vitro infection model in an effort to determine if these models are comparable. We have evaluated the activity of clinafloxacin, trovafloxacin, sparfloxacin, and ciprofloxacin in rabbit models againstStaphylococcus aureus and Enterococcus spp. In vitro models were performed simulating the antibiotic pharmacokinetics obtained in the in vivo studies. Models were dosed the same as rabbit models, and SEVs were evaluated at the same time the rabbit vegetations were examined. Clinafloxacin and trovafloxacin were evaluated against methicillin-susceptible (MSSA1199) and -resistant (MRSA494) strains ofS. aureus. Ciprofloxacin was studied against MSSA1199 and MSSA487. Sparfloxacin and clinafloxacin were evaluated againstEnterococcus faecium SF2149 and Enterococcus faecalis WH245, respectively. We found that reductions in SEV bacterial density obtained in the in vitro model were similar to those obtained in rabbit vegetations, indicating that the SEV model may be a valuable tool for assessing antibiotic potential in the treatment of bacterial endocarditis.

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Candida albicans Morphology Dependent Host FGF-2 Response as a Potential Therapeutic Target

10.20944/preprints201902.0025.v1 ◽

2019 ◽

Cited By ~ 1

Author(s):

Sandeep Vellanki ◽

Eun Young Huh ◽

Stephen P. Saville ◽

Soo Chan Lee

Keyword(s):

Candida Albicans ◽

Growth Factor ◽

Underlying Mechanism ◽

Yeast Cells ◽

In Vivo Studies ◽

Infection Model ◽

Physiological Processes ◽

Microbial Infections

Angiogenesis mediated by proteins such as Fibroblast Growth Factor – 2 (FGF-2) is a vital component of normal physiological processes and has also been implicated in contributing to disease state associated with various microbial infections. Previous studies by our group and others have shown that Candida albicans, a common agent of candidiasis, induces FGF-2 expression in vitro, and angiogenesis in brains and kidneys during systemic infections. However, the underlying mechanism(s) via which the fungus increases FGF-2 expression and the role(s) that FGF-2/angiogenesis plays in C. albicans disease remain unknown. Here we show, for the first time, that C. albicans hyphae (and not yeast cells) increase the FGF-2 response in human endothelial cells. Moreover, candidalysin, a toxin secreted exclusively by C. albicans in the hyphal state is required to induce this response. Our in vivo studies show that, in the systemic C. albicans infection model, mice treated with FGF-2 exhibit significantly higher mortality rates when compared to untreated mice not given the angiogenic growth factor. Even treatment with fluconazole could not fully rescue infected animals that were administered FGF-2. Our data suggest that the increase of FGF-2 production/angiogenesis induced by candidalysin contributes to the pathogenicity of C. albicans.

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Antibacterial Mechanisms and Efficacy of Sarecycline in Animal Models of Infection and Inflammation

Antibiotics ◽

10.3390/antibiotics10040439 ◽

2021 ◽

Vol 10 (4) ◽

pp. 439

Author(s):

Christopher G. Bunick ◽

Jonette Keri ◽

S. Ken Tanaka ◽

Nika Furey ◽

Giovanni Damiani ◽

...

Keyword(s):

Broad Spectrum ◽

Bacterial Resistance ◽

Antibiotic Use ◽

In Vivo Studies ◽

Infection Model ◽

Severe Acne ◽

Rat Paw Edema ◽

Infection And Inflammation

Prolonged broad-spectrum antibiotic use is more likely to induce bacterial resistance and dysbiosis of skin and gut microflora. First and second-generation tetracycline-class antibiotics have similar broad-spectrum antibacterial activity. Targeted tetracycline-class antibiotics are needed to limit antimicrobial resistance and improve patient outcomes. Sarecycline is a narrow-spectrum, third-generation tetracycline-class antibiotic Food and Drug Administration (FDA)-approved for treating moderate-to-severe acne. In vitro studies demonstrated activity against clinically relevant Gram-positive bacteria but reduced activity against Gram-negative bacteria. Recent studies have provided insight into how the structure of sarecycline, with a unique C7 moiety, interacts with bacterial ribosomes to block translation and prevent antibiotic resistance. Sarecycline reduces Staphylococcus aureus DNA and protein synthesis with limited effects on RNA, lipid, and bacterial wall synthesis. In agreement with in vitro data, sarecycline demonstrated narrower-spectrum in vivo activity in murine models of infection, exhibiting activity against S. aureus, but reduced efficacy against Escherichia coli compared to doxycycline and minocycline. In a murine neutropenic thigh wound infection model, sarecycline was as effective as doxycycline against S. aureus. The anti-inflammatory activity of sarecycline was comparable to doxycycline and minocycline in a rat paw edema model. Here, we review the antibacterial mechanisms of sarecycline and report results of in vivo studies of infection and inflammation.

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Designing P. aeruginosa synthetic phages with reduced genomes

Scientific Reports ◽

10.1038/s41598-021-81580-2 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Diana P. Pires ◽

Rodrigo Monteiro ◽

Dalila Mil-Homens ◽

Arsénio Fialho ◽

Timothy K. Lu ◽

...

Keyword(s):

Galleria Mellonella ◽

Antibacterial Properties ◽

Genetically Engineered ◽

In Vivo Studies ◽

Infection Model ◽

Promising Therapeutic Approach ◽

Genes Encoding ◽

First Time

AbstractIn the era where antibiotic resistance is considered one of the major worldwide concerns, bacteriophages have emerged as a promising therapeutic approach to deal with this problem. Genetically engineered bacteriophages can enable enhanced anti-bacterial functionalities, but require cloning additional genes into the phage genomes, which might be challenging due to the DNA encapsulation capacity of a phage. To tackle this issue, we designed and assembled for the first time synthetic phages with smaller genomes by knocking out up to 48% of the genes encoding hypothetical proteins from the genome of the newly isolated Pseudomonas aeruginosa phage vB_PaeP_PE3. The antibacterial efficacy of the wild-type and the synthetic phages was assessed in vitro as well as in vivo using a Galleria mellonella infection model. Overall, both in vitro and in vivo studies revealed that the knock-outs made in phage genome do not impair the antibacterial properties of the synthetic phages, indicating that this could be a good strategy to clear space from phage genomes in order to enable the introduction of other genes of interest that can potentiate the future treatment of P. aeruginosa infections.

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67 Current Status and Future Prospective of the Use of Plant Bioactive Compounds in Dairy and Beef Cattle

Journal of Animal Science ◽

10.1093/jas/skab054.222 ◽

2021 ◽

Vol 99 (Supplement_1) ◽

pp. 132-132

Author(s):

Sergio Calsamiglia ◽

Maria Rodriguez-Prado ◽

Gonzalo Fernandez-Turren ◽

Lorena Castillejos

Keyword(s):

Beef Cattle ◽

Essential Oils ◽

Average Daily Gain ◽

Rumen Fermentation ◽

Production Performance ◽

In Vivo Studies ◽

Current Status ◽

The Impact

Abstract In the last 20 years there has been extensive in vitro research on the effects of plant extracts and essential oils on rumen microbial fermentation. The main objectives have been to improve energy metabolism through a reduction in methane emissions and an increase in propionate production; and to improve protein metabolism by reducing proteolysis and deamination. While the positive results from in vitro studies has stimulated the release of commercial products based on blends of essential oils, there is limited in vivo evidence on the rumen fermentation and production performance effects. A literature search was conducted to select in vivo studies where information on rumen fermentation and animal performance was reported. For dairy cattle, we identified 37 studies of which 21 were adequate to test production performance. Ten studies reported increases and 3 decreases in milk yield. For beef cattle, we identified 20 studies with rumen fermentation profile and 22 with performance data. Average daily gain improved in 7 and decreased in 1 study. Only 1 out of 16 studies reported an improvement in feed efficiency. Data indicate that out of more than 500 products tested in vitro, only around 20 have been tested in vivo in different mixtures and doses. The use of statistical approaches will allow to describe the conditions, doses and responses in dairy and beef cattle performance. The search for postruminal effects offers another alternative use. Evidence for effects on the intestinal and systemic effects on the immune system and antioxidant status (i.e., capsicum, garlic, eugenol, cinnamaldehyde curcuma, catechins, anethol or pinene), and in the modulation of metabolic regulation (capsicum, cinnamaldehyde, curcuma or garlic) may open the opportunity for future applications. However, stability of the product in the GI tract, description of the mechanisms of action and the impact of these changes on performance needs to be further demonstrated.

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Melt-Cast Films Significantly Enhance Triamcinolone Acetonide Delivery to the Deeper Ocular Tissues

Pharmaceutics ◽

10.3390/pharmaceutics11040158 ◽

2019 ◽

Vol 11 (4) ◽

pp. 158

Author(s):

Akshaya Tatke ◽

Narendar Dudhipala ◽

Karthik Janga ◽

Bhavik Soneta ◽

Bharathi Avula ◽

...

Keyword(s):

Triamcinolone Acetonide ◽

Polymer Matrix ◽

Rabbit Model ◽

In Vivo Studies ◽

Invasive Technique ◽

Content Uniformity ◽

Scanning Calorimetry ◽

Ocular Tissues

Delivering an effective drug load to the posterior section of the ocular tissues, while using a non-invasive technique, has always been a challenge. In this regard, the goal of the present study was to develop sustained release triamcinolone acetonide (TA) loaded polymeric matrix films for ocular delivery. The TA-films were prepared in two different polymer matrices, with drug loadings of 10% and 20% w/w, and they were evaluated for ocular distribution in vivo in a conscious rabbit model. A 4% w/v TA suspension (TA-C) was used as a control for in vitro and in vivo studies. The TA-films, prepared with melt-cast technology, used polyethylene oxide (PEO) and Soluplus® as the polymer matrix. The films were evaluated with respect to assay, content uniformity, excipient interaction, and permeability across isolated rabbit sclera. The distribution of TA in the ocular tissues, post topical administration, was determined in New Zealand male albino rabbits as a function of dose, and was compared against TA-C. The assay of the 10% and 20% w/w film was in the range from 70–79% and 92–94% for the Soluplus® and PEO films, respectively, and content uniformity was in the range of 95–103% for both the films. The assay of the TA from Soluplus® films was less compared with the PEO films and showed an interaction with TA, as revealed by Differential Scanning Calorimetry (DSC). Hence, Soluplus® films were not selected for further studies. No interaction was observed between the drug and PEO polymer matrix. The enhancement of trans-scleral flux and permeability of TA was about 1.16 and 1.33-folds, respectively, from the 10% w/w PEO and 3.5 and 2.12-folds, respectively, from the 20% w/w PEO films, as compared with TA-C formulations. The in vivo studies demonstrate that significantly higher TA levels were observed in the anterior and posterior segments of the eye at the end of 6h with the PEO films. Therefore, the PEO based polymeric films were able to deliver TA into the back of the eye efficiently and for prolonged periods.

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In VivoEfficacy of Anuran Trypsin Inhibitory Peptides against Staphylococcal Skin Infection and the Impact of Peptide Cyclization

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.04324-14 ◽

2015 ◽

Vol 59 (4) ◽

pp. 2113-2121 ◽

Cited By ~ 9

Author(s):

U. Malik ◽

O. N. Silva ◽

I. C. M. Fensterseifer ◽

L. Y. Chan ◽

R. J. Clark ◽

...

Keyword(s):

Antimicrobial Agents ◽

Cyclic Peptide ◽

Sequence Similarity ◽

Infection Model ◽

Content Type ◽

Wide Range ◽

Inhibitory Activities ◽

The Impact

ABSTRACTStaphylococcus aureusis a virulent pathogen that is responsible for a wide range of superficial and invasive infections. Its resistance to existing antimicrobial drugs is a global problem, and the development of novel antimicrobial agents is crucial. Antimicrobial peptides from natural resources offer potential as new treatments against staphylococcal infections. In the current study, we have examined the antimicrobial properties of peptides isolated from anuran skin secretions and cyclized synthetic analogues of these peptides. The structures of the peptides were elucidated by nuclear magnetic resonance (NMR) spectroscopy, revealing high structural and sequence similarity with each other and with sunflower trypsin inhibitor 1 (SFTI-1). SFTI-1 is an ultrastable cyclic peptide isolated from sunflower seeds that has subnanomolar trypsin inhibitory activity, and this scaffold offers pharmaceutically relevant characteristics. The five anuran peptides were nonhemolytic and noncytotoxic and had trypsin inhibitory activities similar to that of SFTI-1. They demonstrated weakin vitroinhibitory activities againstS. aureus, but several had strong antibacterial activities againstS. aureusin anin vivomurine wound infection model. pYR, an immunomodulatory peptide fromRana sevosa, was the most potent, with complete bacterial clearance at 3 mg · kg−1. Cyclization of the peptides improved their stability but was associated with a concomitant decrease in antimicrobial activity. In summary, these anuran peptides are promising as novel therapeutic agents for treating infections from a clinically resistant pathogen.

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Role of Hyaluronan in Human Adipogenesis: Evidence from in-Vitro and in-Vivo Studies

International Journal of Molecular Sciences ◽

10.3390/ijms20112675 ◽

2019 ◽

Vol 20 (11) ◽

pp. 2675 ◽

Cited By ~ 1

Author(s):

Nicholas Wilson ◽

Robert Steadman ◽

Ilaria Muller ◽

Mohd Draman ◽

D. Aled Rees ◽

...

Keyword(s):

Stem Cell Differentiation ◽

In Vivo Studies ◽

Peroxisome Proliferator ◽

Synthesis Inhibitor ◽

Peroxisome Proliferator Activated Receptor ◽

Inhibitory Role ◽

The Impact

Hyaluronan (HA), an extra-cellular matrix glycosaminoglycan, may play a role in mesenchymal stem cell differentiation to fat but results using murine models and cell lines are conflicting. Our previous data, illustrating decreased HA production during human adipogenesis, suggested an inhibitory role. We have investigated the role of HA in adipogenesis and fat accumulation using human primary subcutaneous preadipocyte/fibroblasts (PFs, n = 12) and subjects of varying body mass index (BMI). The impact of HA on peroxisome proliferator-activated receptor gamma (PPARγ) expression was analysed following siRNA knockdown or HA synthase (HAS)1 and HAS2 overexpression. PFs were cultured in complete or adipogenic medium (ADM) with/without 4-methylumbelliferone (4-MU = HA synthesis inhibitor). Adipogenesis was evaluated using oil red O (ORO), counting adipogenic foci, and measurement of a terminal differentiation marker. Modulating HA production by HAS2 knockdown or overexpression increased (16%, p < 0.04) or decreased (30%, p = 0.01) PPARγ transcripts respectively. The inhibition of HA by 4-MU significantly enhanced ADM-induced adipogenesis with 1.52 ± 0.18- (ORO), 4.09 ± 0.63- (foci) and 2.6 ± 0.21-(marker)-fold increases compared with the controls, also increased PPARγ protein expression (40%, (p < 0.04)). In human subjects, circulating HA correlated negatively with BMI and triglycerides (r = −0.396 (p = 0.002), r = −0.269 (p = 0.038), respectively), confirming an inhibitory role of HA in human adipogenesis. Thus, enhancing HA action may provide a therapeutic target in obesity.

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