Synergistic Effect of the Flavonoid Catechin, Quercetin, or Epigallocatechin Gallate with Fluconazole Induces Apoptosis in Candida tropicalis Resistant to Fluconazole

ABSTRACTFlavonoids are a class of phenolic compounds commonly found in fruits, vegetables, grains, flowers, tea, and wine. They differ in their chemical structures and characteristics. Such compounds show various biological functions and have antioxidant, antimicrobial, anti-inflammatory, and antiapoptotic properties. The aim of this study was to evaluate thein vitrointeractions of flavonoids with fluconazole againstCandida tropicalisstrains resistant to fluconazole, investigating the mechanism of synergism. Three combinations formed by the flavonoids (+)-catechin hydrated, hydrated quercetin, and (−)-epigallocatechin gallate at a fixed concentration with fluconazole were tested. Flavonoids alone had no antifungal activity within the concentration range tested, but when they were used as a cotreatment with fluconazole, there was significant synergistic activity. From this result, we set out to evaluate the possible mechanisms of cell death involved in this synergism. Isolated flavonoids did not induce morphological changes or changes in membrane integrity in the strains tested, but when they were used as a cotreatment with fluconazole, these changes were quite significant. When evaluating mitochondrial damage and the production of reactive oxygen species (ROS) only in the cotreatment, changes were observed. Flavonoids combined with fluconazole were shown to cause a significant increase in the rate of damage and the frequency of DNA damage in the tested strains. The cotreatment also induced an increase in the externalization of phosphatidylserine, an important marker of early apoptosis. It is concluded that flavonoids, when combined with fluconazole, show activity against strains ofC. tropicalisresistant to fluconazole, promoting apoptosis by exposure of phosphatidylserine in the plasma membrane and morphological changes, mitochondrial depolarization, intracellular accumulation of ROS, condensation, and DNA fragmentation.

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Synergistic Activity of Chloroquine with Fluconazole against Fluconazole-Resistant Isolates of Candida Species

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.04417-14 ◽

2014 ◽

Vol 59 (2) ◽

pp. 1365-1369 ◽

Cited By ~ 10

Author(s):

Yali Li ◽

Zhe Wan ◽

Wei Liu ◽

Ruoyu Li

Keyword(s):

Candida Albicans ◽

Synergistic Effect ◽

Candida Tropicalis ◽

Candida Krusei ◽

Synergistic Activity ◽

Broth Microdilution ◽

Content Type ◽

Fluconazole Resistant ◽

Susceptibility Tests

ABSTRACTThein vitroactivity of chloroquine and the interactions of chloroquine combined with fluconazole against 37Candidaisolates were tested using the broth microdilution, disk diffusion, and Etest susceptibility tests. Synergistic effect was detected with 6 of 9 fluconazole-resistantCandida albicansisolates, withCandida kruseiATCC 6258, and with all 12 fluconazole-resistantCandida tropicalisisolates.

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In vitro synergistic activity of aztreonam (AZT) plus novel and old β-lactamase inhibitor combinations against metallo-β-lactamase-producing AZT-resistant Enterobacterales

Journal of Medical Microbiology ◽

10.1099/jmm.0.001427 ◽

2021 ◽

Vol 70 (10) ◽

Author(s):

Ivan Cervino ◽

Deborah Gonzalez ◽

Marcela Nastro ◽

Juana Vega ◽

Ana Paula Reyes ◽

...

Keyword(s):

Screening Method ◽

Dilution Method ◽

Agar Dilution Method ◽

New Delhi ◽

Synergistic Activity ◽

Content Type ◽

Link Type ◽

Fixed Concentration ◽

Mueller Hinton Agar

The emergence of metallo-β-lactamase (MBL)-producing Enterobacterales , mainly New Delhi metallo-β-lactamase (NDM), represents a clinical threat due to the limited therapeutic alternatives. Aztreonam (AZT) is stable to MBLs, but most MBL-producing Enterobacterales isolates usually co-harbour other β-lactamases that confer resistance to AZT and, consequently, its use is restricted in these isolates. We compared the ability of sulbactam (SUL), tazobactam (TAZ), clavulanic acid (CLA) and avibactam (AVI) to restore the AZT activity in MBL-producing AZT-resistant Enterobacterales isolates. A collection of 64 NDM-producing AZT-resistant Enterobacterales from five hospitals in Buenos Aires city, Argentina, were studied during the period July–December 2020. MICs were determined using the agar dilution method with Mueller–Hinton agar according to Clinical and Laboratory Standards Institute (CLSI) recommendations. AVI, SUL and TAZ were used at a fixed concentration of 4 mg l−1, whereas CLA was used at a fixed concentration of 2 mg l−1. A screening method based on disc diffusion to evaluate this synergy was also conducted. Detection of bla KPC, bla OXA, bla NDM, bla VIM, bla CTXM-1, bla PER-2 and bla CIT was performed by PCR. The AZT-AVI combination restored the AZT activity in 98.4 % of AZT-resistant strains, whereas CLA, TAZ and SUL did so in 70.3, 15.6 and 12.5 %, respectively, in isolates co-harbouring extended-spectrum β-lactamases, but were inactive in isolates harbouring AmpC-type enzymes and/or KPC. The synergy screening test showed an excellent negative predictive value to confirm the absence of synergy, but positive results should be confirmed by a quantitative method. The excellent in vitro performance of the AZT-CLA combination represents a much more economical alternative to AZT-AVI, which could be of use in the treatment of MBL-producing, AZT-resistant Enterobacterales .

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Synergistic Activity of the Tyrocidines, Antimicrobial Cyclodecapeptides from Bacillus aneurinolyticus, with Amphotericin B and Caspofungin against Candida albicans Biofilms

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.02381-14 ◽

2014 ◽

Vol 58 (7) ◽

pp. 3697-3707 ◽

Cited By ~ 33

Author(s):

Anscha Mari Troskie ◽

Marina Rautenbach ◽

Nicolas Delattin ◽

Johan Arnold Vosloo ◽

Margitta Dathe ◽

...

Keyword(s):

Candida Albicans ◽

Amphotericin B ◽

Membrane Integrity ◽

Antifungal Drugs ◽

Infection Model ◽

Synergistic Activity ◽

Significant Activity ◽

Content Type ◽

Micromolar Range

ABSTRACTTyrocidines are cationic cyclodecapeptides fromBacillus aneurinolyticusthat are characterized by potent antibacterial and antimalarial activities. In this study, we show that various tyrocidines have significant activity against planktonicCandida albicansin the low-micromolar range. These tyrocidines also preventedC. albicansbiofilm formationin vitro. Studies with the membrane-impermeable dye propidium iodide showed that the tyrocidines disrupt the membrane integrity of matureC. albicansbiofilm cells. This membrane activity correlated with the permeabilization and rapid lysis of model fungal membranes containing phosphatidylcholine and ergosterol (70:30 ratio) induced by the tyrocidines. The tyrocidines exhibited pronounced synergistic biofilm-eradicating activity in combination with two key antifungal drugs, amphotericin B and caspofungin. Using aCaenorhabditis elegansinfection model, we found that tyrocidine A potentiated the activity of caspofungin. Therefore, tyrocidines are promising candidates for further research as antifungal drugs and as agents for combinatorial treatment.

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Parasexuality and Ploidy Change in Candida tropicalis

Eukaryotic Cell ◽

10.1128/ec.00128-13 ◽

2013 ◽

Vol 12 (12) ◽

pp. 1629-1640 ◽

Cited By ~ 20

Author(s):

Riyad N. H. Seervai ◽

Stephen K. Jones ◽

Matthew P. Hirakawa ◽

Allison M. Porman ◽

Richard J. Bennett

Keyword(s):

Sexual Reproduction ◽

Candida Tropicalis ◽

Culture Conditions ◽

Sexual Cycle ◽

Chromosome Loss ◽

Parasexual Cycle ◽

Content Type ◽

Ploidy Changes ◽

Diploid Cells

ABSTRACTCandidaspecies exhibit a variety of ploidy states and modes of sexual reproduction. Most species possess the requisite genes for sexual reproduction, recombination, and meiosis, yet only a few have been reported to undergo a complete sexual cycle including mating and sporulation.Candida albicans, the most studiedCandidaspecies and a prevalent human fungal pathogen, completes its sexual cycle via a parasexual process of concerted chromosome loss rather than a conventional meiosis. In this study, we examine ploidy changes inCandida tropicalis, a closely related species toC. albicansthat was recently revealed to undergo sexual mating.C. tropicalisdiploid cells mate to form tetraploid cells, and we show that these can be induced to undergo chromosome loss to regenerate diploid forms by growth on sorbose medium. The diploid products are themselves mating competent, thereby establishing a parasexual cycle in this species for the first time. Extended incubation (>120 generations) ofC. tropicalistetraploid cells under rich culture conditions also resulted in instability of the tetraploid form and a gradual reduction in ploidy back to the diploid state. The fitness levels ofC. tropicalisdiploid and tetraploid cells were compared, and diploid cells exhibited increased fitness relative to tetraploid cellsin vitro, despite diploid and tetraploid cells having similar doubling times. Collectively, these experiments demonstrate distinct pathways by which a parasexual cycle can occur inC. tropicalisand indicate that nonmeiotic mechanisms drive ploidy changes in this prevalent human pathogen.

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Semimechanistic Pharmacokinetic/Pharmacodynamic Modeling of Fosfomycin and Sulbactam Combination against Carbapenem-Resistant Acinetobacter baumannii

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.02472-20 ◽

2021 ◽

Vol 65 (5) ◽

Author(s):

Sazlyna Mohd Sazlly Lim ◽

Aaron J. Heffernan ◽

Jason A. Roberts ◽

Fekade B. Sime

Keyword(s):

Acinetobacter Baumannii ◽

Treatment Options ◽

Pharmacodynamic Modeling ◽

Synergistic Activity ◽

Bacterial Burden ◽

Target Attainment ◽

Content Type ◽

Carbapenem Resistant ◽

Time Kill

ABSTRACT Due to limited treatment options for carbapenem-resistant Acinetobacter baumannii (CR-AB) infections, antibiotic combinations are now considered potential treatments for CR-AB. This study aimed to explore the utility of fosfomycin-sulbactam combination (FOS/SUL) therapy against CR-AB isolates. Synergism of FOS/SUL against 50 clinical CR-AB isolates was screened using the checkerboard method. Thereafter, time-kill studies against two CR-AB isolates were performed. The time-kill data were described using a semimechanistic pharmacokinetic/pharmacodynamic (PK/PD) model. Monte Carlo simulations were then performed to estimate the probability of stasis, 1-log kill, and 2-log kill after 24 h of combination therapy. The FOS/SUL combination demonstrated a synergistic effect against 74% of isolates. No antagonism was observed. The MIC50 and MIC90 of FOS/SUL were decreased 4- to 8-fold, compared to the monotherapy MIC50 and MIC90. In the time-kill studies, the combination displayed bactericidal activity against both isolates and synergistic activity against one isolate at the highest clinically achievable concentrations. Our PK/PD model was able to describe the interaction between fosfomycin and sulbactam in vitro. Bacterial kill was mainly driven by sulbactam, with fosfomycin augmentation. FOS/SUL regimens that included sulbactam at 4 g every 8 h demonstrated a probability of target attainment of 1-log10 kill at 24 h of ∼69 to 76%, compared to ∼15 to 30% with monotherapy regimens at the highest doses. The reduction in the MIC values and the achievement of a moderate PTA of a 2-log10 reduction in bacterial burden demonstrated that FOS/SUL may potentially be effective against some CR-AB infections.

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The dynamics of morphological changes during in vitro aging of bovine virgin mammary gland neutrophils

Veterinární Medicína ◽

10.17221/5843-vetmed ◽

2012 ◽

Vol 47 (No. 12) ◽

pp. 325-332 ◽

Cited By ~ 1

Author(s):

Z. Sládek ◽

D. Vašíčková ◽

D. Ryšánek

Keyword(s):

Mammary Gland ◽

Trypan Blue ◽

Morphological Changes ◽

Membrane Integrity ◽

Mammary Glands ◽

Progressive Increase ◽

Apoptotic Bodies ◽

Bovine Mammary Gland ◽

Cell Counts

The present study was an in vitro analysis of the dynamics of bovine mammary gland neutrophil apoptosis based on the detection of morphological changes. The neutrophils were isolated from mammary glands of five virgin heifers. The mammary glands were lavaged, the suspensions were then bacteriologically examined, and total and differential cell counts were made. The cells were cultivated in vitro for 4 hours. After 2, 3 and 4 hours of cultivation, they were panoptically stained, and the proportions of apoptotic neutrophils and trypan blue positive neutrophils were determined. Neutrophil apoptosis and impaired cytoplasmic membrane integrity of neutrophils were already observed in the mammary gland lavages (11.9% and 0.8%, respectively). During the cultivation, a progressive increase in the number of apoptotic neutrophils in various stages of apoptosis – karyopyknosis, zeiosis and apoptotic bodies – was observed. Karyopyknotic neutrophils represented a dominant part of the apoptotic neutrophil population in the course of the whole cultivation. The most intensive increase was observed in zeiosis, whereas the levels of apoptotic bodies remained the same. After 4 hours of cultivation, 31.7% apoptotic neutrophils and 9.8% trypan blue positive neutrophils (i.e. Secondary necrotic cells) were found. The results of this work show that spontaneous apoptosis and secondary neutrophil necrosis must be taken into account during in vitro cultivations of bovine mammary gland neutrophils.

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Synergistic Activity between Statins and Bisphosphonates against Acute Experimental Toxoplasmosis

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.02628-16 ◽

2017 ◽

Vol 61 (8) ◽

Cited By ~ 6

Author(s):

Zhu-Hong Li ◽

Catherine Li ◽

Sergio H. Szajnman ◽

Juan B. Rodriguez ◽

Silvia N. J. Moreno

Keyword(s):

Lethal Dose ◽

Inhibitory Effect ◽

Etiologic Agent ◽

Farnesyl Diphosphate ◽

Synergistic Activity ◽

Content Type ◽

Coa Reductase ◽

Modest Effect

ABSTRACT Bisphosphonates are widely used for the treatment of bone disorders. These drugs also inhibit the growth of a variety of protozoan parasites, such as Toxoplasma gondii, the etiologic agent of toxoplasmosis. The target of the most potent bisphosphonates is the isoprenoid biosynthesis pathway enzyme farnesyl diphosphate synthase (FPPS). Based on our previous work on the inhibitory effect of sulfur-containing linear bisphosphonates against T. gondii, we investigated the potential synergistic interaction between one of these derivatives, 1-[(n-heptylthio)ethyl]-1,1-bisphosphonate (C7S), and statins, which are potent inhibitors of the host 3-hydroxy-3-methyl glutaryl-coenzyme A reductase (3-HMG-CoA reductase). C7S showed high activity against the T. gondii bifunctional farnesyl diphosphate (FPP)/geranylgeranyl diphosphate (GGPP) synthase (TgFPPS), which catalyzes the formation of FPP and GGPP (50% inhibitory concentration [IC50] = 31 ± 0.01 nM [mean ± standard deviation]), and modest effect against the human FPPS (IC50 = 1.3 ± 0.5 μM). We tested combinations of C7S with statins against the in vitro replication of T. gondii. We also treated mice infected with a lethal dose of T. gondii with similar combinations. We found strong synergistic activities when using low doses of C7S, which were stronger in vivo than when tested in vitro. We also investigated the synergism of several commercially available bisphosphonates with statins both in vitro and in vivo. Our results provide evidence that it is possible to develop drug combinations that act synergistically by inhibiting host and parasite enzymes in vitro and in vivo.

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In VitroCombination of Isavuconazole with Micafungin or Amphotericin B Deoxycholate against Medically Important Molds

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.03261-14 ◽

2014 ◽

Vol 58 (11) ◽

pp. 6934-6937 ◽

Cited By ~ 25

Author(s):

Aspasia Katragkou ◽

Matthew McCarthy ◽

Joseph Meletiadis ◽

Vidmantas Petraitis ◽

Patriss W. Moradi ◽

...

Keyword(s):

Combination Therapy ◽

Invasive Aspergillosis ◽

Amphotericin B ◽

Aspergillus Flavus ◽

Aspergillus Terreus ◽

Synergistic Activity ◽

Content Type ◽

Amphotericin B Deoxycholate ◽

Combination Studies

ABSTRACTWhether isavuconazole, an extended-spectrum triazole, possesses synergistic activity in combination therapy with echinocandins or amphotericin B for the treatment of invasive molds infections has not been studied. Ourin vitrocombination studies showed that isavuconazole and micafungin are synergistically active againstAspergillus fumigatus,Aspergillus flavus,Aspergillus terreus, andCunninghamella bertholletiae. These results suggest that isavuconazole, in combination with micafungin, may have a role in the treatment of invasive aspergillosis and warrants further investigation.

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Clomipramine and Benznidazole Act Synergistically and Ameliorate the Outcome of Experimental Chagas Disease

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.00404-16 ◽

2016 ◽

Vol 60 (6) ◽

pp. 3700-3708 ◽

Cited By ~ 12

Author(s):

Mónica Cristina García ◽

Nicolás Eric Ponce ◽

Liliana Maria Sanmarco ◽

Rubén Hilario Manzo ◽

Alvaro Federico Jimenez-Kairuz ◽

...

Keyword(s):

Synergistic Effect ◽

Chagas Disease ◽

Drug Combination ◽

Specific Inhibitor ◽

Chronic Phase ◽

Control Group ◽

Histopathological Analysis ◽

Synergistic Activity ◽

Content Type

Chagas disease is an important public health problem in Latin America, and its treatment by chemotherapy with benznidazole (BZ) or nifurtimox remains unsatisfactory. In order to design new alternative strategies to improve the current etiological treatments, in the present work, we comprehensively evaluated thein vitroandin vivoanti-Trypanosoma cruzieffects of clomipramine (CMP) (a parasite-trypanothione reductase-specific inhibitor) combined with BZ.In vitrostudies, carried out using a checkerboard technique on trypomastigotes (T. cruzistrain Tulahuen), revealed a combination index (CI) of 0.375, indicative of a synergistic effect of the drug combination. This result was correlated with the data obtained in infected BALB/c mice. We observed that during the acute phase (15 days postinfection [dpi]), BZ at 25 mg/kg of body weight/day alone decreased the levels of parasitemia compared with those of the control group, but when BZ was administered with CMP, the drug combination completely suppressed the parasitemia due to the observed synergistic effect. Furthermore, in the chronic phase (90 dpi), mice treated with both drugs showed less heart damage as assessed by the histopathological analysis, index of myocardial inflammation, and levels of heart injury biochemical markers than mice treated with BZ alone at the reference dose (100 mg/kg/day). Collectively, these data support the notion that CMP combined with low doses of BZ diminishes cardiac damage and inflammation during the chronic phase of cardiomyopathy. The synergistic activity of BZ-CMP clearly suggests a potential drug combination for Chagas disease treatment, which would allow a reduction of the effective dose of BZ and an increase in therapeutic safety.

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The F-Box Protein Fbp1 Regulates Sexual Reproduction and Virulence in Cryptococcus neoformans

Eukaryotic Cell ◽

10.1128/ec.00004-11 ◽

2011 ◽

Vol 10 (6) ◽

pp. 791-802 ◽

Cited By ~ 25

Author(s):

Tong-Bao Liu ◽

Yina Wang ◽

Sabriya Stukes ◽

Qing Chen ◽

Arturo Casadevall ◽

...

Keyword(s):

Sexual Reproduction ◽

Cryptococcus Neoformans ◽

Stress Responses ◽

Membrane Integrity ◽

Infection Model ◽

Calcofluor White ◽

Fungal Virulence ◽

Content Type ◽

F Box Protein

ABSTRACTCryptococcus neoformansis the leading cause of fungal meningitis in immunocomprised populations. Although extensive studies have been conducted on signal transduction pathways important for fungal sexual reproduction and virulence, how fungal virulence is regulated during infection is still not understood. In this study, we identified the F-box protein Fbp1, which contains a putative F-box domain and 12 leucine-rich repeats (LRR). Althoughfbp1mutants showed normal growth and produced normal major virulence factors, such as melanin and capsule, Fbp1 was found to be essential for fungal virulence, asfbp1mutants were avirulent in a murine systemic-infection model. Fbp1 is also important for fungal sexual reproduction. Basidiospore production was blocked in bilateral mating betweenfbp1mutants, even though normal dikaryotic hyphae were observed during mating.In vitroassays of stress responses revealed thatfbp1mutants are hypersensitive to SDS, but not calcofluor white (CFW) or Congo red, indicating that Fbp1 may regulate cell membrane integrity. Fbp1 physically interacts with Skp1 homologues in bothSaccharomyces cerevisiaeandC. neoformansvia its F-box domain, suggesting it may function as part of an SCF (Skp1, Cullins, F-box proteins) E3 ligase. Overall, our study revealed that the F-box protein Fbp1 is essential for fungal sporulation and virulence inC. neoformans, which likely represents a conserved novel virulence control mechanism that involves the SCF E3 ubiquitin ligase-mediated proteolysis pathway.

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