Project description:A G3P2 patient who conceived while using an intrauterine contraceptive device (IUD) presented at 20 weeks of gestation with mild irregular uterine contractions and vaginal bleeding. Sonographic examination at admission showed the presence of dense amniotic fluid "sludge" and a long sonographic uterine cervix (42 mm). To assess the microbiologic significance of amniotic fluid "sludge", we performed a transabdominal amniocentesis. The procedure was performed under real-time ultrasound, and fluid resembling pus at gross examination was noted. Rapid amniotic fluid analysis showed the presence of a high white blood cell count and structures resembling hyphae. Amniotic fluid cultures were positive for Candida albicans. Treatment was begun with broad-spectrum antibiotics, including Fluconazole, upon the visualization of pus in the "sludge" material because of the presence of hyphae in the Gram stain. Despite treatment, the patient went into spontaneous preterm labor and delivered five days after admission. Placental examination revealed acute fungal histologic chorioamnionitis and funisitis. This represents the first report of transabdominal collection and analysis of amniotic fluid "sludge" and the microbiologic detection of Candida albicans in this material. This report provides evidence that transabdominal retrieval of "sludge" is possible and may be of significant value for patient management and selection of antimicrobial agents.
Project description:New Candida species may cause bloodstream infections challenging current therapeutic approaches because of unpredictable susceptibility and virulence. In the present report, we describe a fungemia case due to Candida pulcherrima in a premature neonate. After full in vitro diagnostic workup, the neonate was successfully treated with liposomal amphotericin B and micafungin achieving rapid fungal eradication from blood.
Project description:Chorioamnionitis is caused by intrauterine infection with microorganisms including Candida albicans (C.albicans). Chorioamnionitis is associated with postnatal intestinal pathologies including necrotizing enterocolitis. The underlying mechanisms by which intra-amniotic C.albicans infection adversely affects the fetal gut remain unknown. Therefore, we assessed whether intra-amniotic C.albicans infection would cause intestinal inflammation and mucosal injury in an ovine model. Additionally, we tested whether treatment with the fungistatic fluconazole ameliorated the adverse intestinal outcome of intra-amniotic C.albicans infection. Pregnant sheep received intra-amniotic injections with 10(7) colony-forming units C.albicans or saline at 3 or 5 days before preterm delivery at 122 days of gestation. Fetuses were given intra-amniotic and intra-peritoneal fluconazole treatments 2 days after intra-amniotic administration of C.albicans. Intra-amniotic C.albicans caused intestinal colonization and invasive growth within the fetal gut with mucosal injury and intestinal inflammation, characterized by increased CD3(+) lymphocytes, MPO(+) cells and elevated TNF-α and IL-17 mRNA levels. Fluconazole treatment in utero decreased intestinal C.albicans colonization, mucosal injury but failed to attenuate intestinal inflammation. Intra-amniotic C.albicans caused intestinal infection, injury and inflammation. Fluconazole treatment decreased mucosal injury but failed to ameliorate C.albicans-mediated mucosal inflammation emphasizing the need to optimize the applied antifungal therapeutic strategy.
Project description:ObjectiveThe aims of this study were as follows. First, we sought to compare the in vitro susceptibility of liposomal amphotericin B (LAmB) and anidulafungin on Candida albicans and Candida glabrata biofilms growing on silicone discs. Second, we sought to compare the activity of LAmB versus anidulafungin for the treatment of experimental catheter-related C. albicans and C. glabrata infections with the antifungal lock technique in a rabbit model.MethodsTwo C. albicans and two C. glabrata clinical strains were used. The minimum biofilm eradication concentration for 90% eradication (MBEC90) values were determined after 48h of treatment with LAmB and anidulafungin. Confocal microscopy was used to visualize the morphology and viability of yeasts growing in biofilms. Central venous catheters were inserted into New Zealand rabbits, which were inoculated of each strain of C. albicans and C. glabrata. Then, catheters were treated for 48h with saline or with antifungal lock technique using either LAmB (5mg/mL) or anidulafungin (3.33mg/mL).ResultsIn vitro: anidulafungin showed greater activity than LAmB against C. albicans and C. glabrata strains. For C. albicans: MBEC90 of anidulafungin versus LAmB: CA176, 0.03 vs. 128 mg/L; CA180, 0.5 vs. 64 mg/L. For C. glabrata: MBEC90 of anidulafungin versus LAmB: CG171, 0.5 vs. 64 mg/L; CG334, 2 vs. 32 mg/L. In vivo: for C. albicans species, LAmB and anidulafungin achieved significant reductions relative to growth control of log10 cfu recovered from the catheter tips (CA176: 3.6±0.3 log10 CFU, p≤0.0001; CA180: 3.8±0.1 log10 CFU, p≤0.01). For C. glabrata, anidulafungin lock therapy achieved significant reductions relative to the other treatments (CG171: 4.8 log10 CFU, p≤0.0001; CG334: 5.1 log10 CFU, p≤0.0001).ConclusionsFor the C. albicans strains, both LAmB and anidulafungin may be promising antifungal lock technique for long-term catheter-related infections; however, anidulafungin showed significantly higher activity than LAmB against the C. glabrata strains.
Project description:Amphotericin B is an antibiotic used as the "gold standard" in the treatment of life-threatening fungal infections. Several molecular mechanisms have been proposed to explain exceptionally high effectiveness of amphotericin B in combating fungi. In the present work, we apply fluorescence lifetime imaging microscopy to track, step by step, modes of the toxic activity of amphotericin B towards a clinical strain of Candida albicans. The images recorded reveal that the antibiotic binds to cells in the form of the small aggregates characterized by a relatively short fluorescence lifetime (0.2 ns). Amphotericin B binds preferentially to the cell walls of mature cells but also to the plasma membranes of the daughter cells at the budding stage. The images recorded with the application of a scanning electron microscopy show that the antibiotic interferes with the formation of functional cell walls of such young cells. The results of imaging reveal the formation of the amphotericin B-rich extramembranous structures and also binding of the drug molecules into the cell membranes and penetration into the cells. These two modes of action of amphotericin B are observed in the time scale of minutes.
Project description:Candida albicans is a commensal fungus of the human gastrointestinal tract and a prevalent opportunistic pathogen. To examine diversity within this species, extensive genomic and phenotypic analyses were performed on 21 clinical C. albicans isolates. Genomic variation was evident in the form of polymorphisms, copy number variations, chromosomal inversions, subtelomeric hypervariation, loss of heterozygosity (LOH), and whole or partial chromosome aneuploidies. All 21 strains were diploid, although karyotypic changes were present in eight of the 21 isolates, with multiple strains being trisomic for Chromosome 4 or Chromosome 7. Aneuploid strains exhibited a general fitness defect relative to euploid strains when grown under replete conditions. All strains were also heterozygous, yet multiple, distinct LOH tracts were present in each isolate. Higher overall levels of genome heterozygosity correlated with faster growth rates, consistent with increased overall fitness. Genes with the highest rates of amino acid substitutions included many cell wall proteins, implicating fast evolving changes in cell adhesion and host interactions. One clinical isolate, P94015, presented several striking properties including a novel cellular phenotype, an inability to filament, drug resistance, and decreased virulence. Several of these properties were shown to be due to a homozygous nonsense mutation in the EFG1 gene. Furthermore, loss of EFG1 function resulted in increased fitness of P94015 in a commensal model of infection. Our analysis therefore reveals intra-species genetic and phenotypic differences in C. albicans and delineates a natural mutation that alters the balance between commensalism and pathogenicity.
Project description:Candida albicans is one of the most common human fungal pathogens and represents the most important cause of opportunistic mycoses worldwide. Surgical devices including catheters are easily contaminated with C. albicans via its formation of drug-resistant biofilms. In this study, amphotericin-B-resistant C. albicans strains were isolated from surgical devices at an intensive care center. The objective of this study was to develop optimized effective inhibitory treatment of resistant C. albicans by terpenoids, known to be produced naturally as protective signals. Endogenously produced farnesol by C. albicans yeast and plant terpenoids, carvacrol, and cuminaldehyde were tested separately or in combination on amphotericin-B-resistant C. albicans in either single- or mixed-infections. The results showed that farnesol did not inhibit hyphae formation when associated with bacteria. Carvacrol and cuminaldehyde showed variable inhibitory effects on C. albicans yeast compared to hyphae formation. A combination of farnesol with carvacrol showed synergistic inhibitory activities not only on C. albicans yeast and hyphae, but also on biofilms formed from single- and mixed-species and at reduced doses. The combined terpenoids also showed biofilm-penetration capability. The aforementioned terpenoid combination will not only be useful in the treatment of different resistant Candida forms, but also in the safe prevention of biofilm formation.
Project description:BackgroundBiofilms are the leading cause of nosocomial infections and are hard to eradicate due to their inherent antimicrobial resistance. Candida albicans is the leading cause of nosocomial fungal infections and is frequently co-isolated with the bacterium Pseudomonas aeruginosa from biofilms in the cystic fibrosis lung and severe burn wounds. The presence of C. albicans in multispecies biofilms is associated with enhanced antibacterial resistance, which is largely mediated through fungal extracellular carbohydrates sequestering the antibiotics. However, significantly less is known regarding the impact of polymicrobial biofilms on antifungal resistance.ResultsHere we show that, in dual-species biofilms, P. aeruginosa enhances the susceptibility of C. albicans to amphotericin B, an effect that was biofilm specific. Transcriptional analysis combined with gene ontology enrichment analysis identified several C. albicans processes associated with oxidative stress to be differentially regulated in dual-species biofilms, suggesting that P. aeruginosa exerts oxidative stress on C. albicans, likely through the secretion of phenazines. However, the mitochondrial superoxide dismutase SOD2 was significantly down-regulated in the presence of P. aeruginosa. Monospecies biofilms of the sod2Δ mutant were more susceptible to amphotericin B, and the susceptibility of these biofilms was further enhanced by exogenous phenazines.ConclusionsWe propose that in dual-species biofilms, P. aeruginosa simultaneously induces mitochondrial oxidative stress, while down-regulating key detoxification enzymes, which prevents C. albicans mounting an appropriate oxidative stress response to amphotericin B, leading to fungal cell death. This work highlights the importance of understanding the impact of polymicrobial interactions on antimicrobial susceptibility.
Project description:ObjectiveThe present study aimed to elucidate the cell death mechanism in Leishmania donovani upon treatment with KalsomeTM10, a new liposomal amphotericin B.Methodology/principal findingsWe studied morphological alterations in promastigotes through phase contrast and scanning electron microscopy. Phosphatidylserine (PS) exposure, loss of mitochondrial membrane potential and disruption of mitochondrial integrity was determined by flow cytometry using annexinV-FITC, JC-1 and mitotraker, respectively. For analysing oxidative stress, generation of H2O2 (bioluminescence kit) and mitochondrial superoxide O2- (mitosox) were measured. DNA fragmentation was evaluated using terminal deoxyribonucleotidyl transferase mediated dUTP nick-end labelling (TUNEL) and DNA laddering assay. We found that KalsomeTM10 is more effective then Ambisome against the promastigote as well as intracellular amastigote forms. The mechanistic study showed that KalsomeTM10 induced several morphological alterations in promastigotes typical of apoptosis. KalsomeTM10 treatment showed a dose- and time-dependent exposure of PS in promastigotes. Further, study on mitochondrial pathway revealed loss of mitochondrial membrane potential as well as disruption in mitochondrial integrity with depletion of intracellular pool of ATP. KalsomeTM10 treated promastigotes showed increased ROS production, diminished GSH levels and increased caspase-like activity. DNA fragmentation and cell cycle arrest was observed in KalsomeTM10 treated promastigotes. Apoptotic DNA fragmentation was also observed in KalsomeTM10 treated intracellular amastigotes. KalsomeTM10 induced generation of ROS and nitric oxide leads to the killing of the intracellular parasites. Moreover, endocytosis is indispensable for KalsomeTM10 mediated anti-leishmanial effect in host macrophage.ConclusionsKalsomeTM10 induces apoptotic-like cell death in L. donovani parasites to exhibit its anti-leishmanial function.
Project description:A new class of fungal biofilm inhibitors represented by shearinines D (3) and E (4) were obtained from a Penicillium sp. isolate. The inhibitory activities of 3 and 4 were characterized using a new imaging flow-cytometer technique, which enabled the rapid phenotypic analysis of Candida albicans cell types (budding yeast cells, germ tube cells, pseudohyphae, and hyphae) in biofilm populations. The results were confirmed by experimental data obtained from three-dimensional confocal laser scanning microscopy and 2,3-bis(2-methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-carboxanilide (XTT) assays. These data indicate that 3 and 4 inhibited C. albicans biofilm formation by blocking the outgrowth of hyphae at a relatively late stage of biofilm development (IC50 = 8.5 and 7.6 μM, respectively). However, 3 and 4 demonstrated comparatively weak activity at disrupting existing biofilms. Compounds 3 and 4 also exhibited synergistic activities with amphotericin B against C. albicans and other clinical Candida isolates by enhancing the potency of amphotericin B up to 8-fold against cells in both developing and established biofilms. These data suggest that the Candida biofilm disruption and amphotericin B potentiating effects of 3 and 4 could be mediated through multiple biological targets. The shearinines are good tools for testing the potential advantages of using adjunctive therapies in combination with antifungals.