Novel and potent antimicrobial effects of caspofungin on drug-resistant Candida and bacteria

Abstract Echinocandins, including caspofungin, micafungin, and anidulafungin, are first-line antifungal agents for the treatment of invasive candidiasis. They exhibit fungicidal activity by inhibiting the synthesis of β-1,3-d-glucan, an essential component of the fungal cell wall. However, they are active only against proliferating fungal cells and unable to completely eradicate fungal cells even after a 24 h drug exposure in standard time-kill assays. Surprisingly, we found that caspofungin, when dissolved in low ionic solutions, had rapid and potent antimicrobial activities against multidrug-resistant (MDR) Candida and bacteria cells even in non-growth conditions. This effect was not observed in 0.9% NaCl or other ion-containing solutions and was not exerted by other echinocandins. Furthermore, caspofungin dissolved in low ionic solutions drastically reduced mature biofilm cells of MDR Candida auris in only 5 min, as well as Candida-bacterial polymicrobial biofilms in a catheter-lock therapy model. Caspofungin displayed ion concentration-dependent conformational changes and intracellular accumulation with increased reactive oxygen species production, indicating a novel mechanism of action in low ionic conditions. Importantly, caspofungin dissolved in 5% glucose water did not exhibit increased toxicity to human cells. This study facilitates the development of new therapeutic strategies in the management of catheter-related biofilm infections.

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Ibrexafungerp: A Novel Oral Triterpenoid Antifungal in Development for the Treatment of Candida auris Infections

Antibiotics ◽

10.3390/antibiotics9090539 ◽

2020 ◽

Vol 9 (9) ◽

pp. 539

Author(s):

Mahmoud Ghannoum ◽

Maiken Cavling Arendrup ◽

Vishnu P. Chaturvedi ◽

Shawn R. Lockhart ◽

Thomas S. McCormick ◽

...

Keyword(s):

Antifungal Agent ◽

Complete Response ◽

Clinical Results ◽

Multidrug Resistant ◽

Candida Auris ◽

Open Label ◽

Candida Spp ◽

Fungal Cell ◽

Novel Treatments

Candida auris is an emerging multidrug-resistant fungal pathogen reported worldwide. Infections due to C. auris are usually nosocomial and associated with high rates of fluconazole resistance and mortality. Echinocandins are utilized as the first-line treatment. However, echinocandins are only available intravenously and are associated with increasingly higher rates of resistance by C. auris. Thus, a need exists for novel treatments that demonstrate potent activity against C. auris. Ibrexafungerp is a first-in-class triterpenoid antifungal agent. Similar to echinocandins, ibrexafungerp inhibits (1→3)-β-D-glucan synthase, a key component of the fungal cell wall, resulting in fungicidal activity against Candida spp. Ibrexafungerp demonstrates broad in vitro activity against various Candida spp. including C. auris and C. auris isolates with fks mutations. Minimum inhibitory concentration (MIC50 and MIC90) values in >400 C. auris isolates were 0.5 μg/mL and 1.0 μg/mL, respectively. Clinical results were reported for two patients with invasive candidiasis or candidemia due to C. auris treated during the CARES (Candidiasis Caused by Candida Auris) trial, an ongoing open-label study. These patients experienced a complete response after treatment with ibrexafungerp. Thus, ibrexafungerp represents a promising new antifungal agent for treating C. auris infections.

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Photoinactivation of catalase sensitizes Candida albicans and Candida auris to ROS-producing agents and immune cells

10.1101/2021.08.31.458449 ◽

2021 ◽

Author(s):

Pu-Ting Dong ◽

Yuewei Zhan ◽

Sebastian Jusuf ◽

Jie Hui ◽

Zeina Dagher ◽

...

Keyword(s):

Candida Albicans ◽

Blue Light ◽

Optical Switch ◽

Multidrug Resistant ◽

Fungal Species ◽

Candida Auris ◽

Fungal Cell ◽

Wide Range ◽

Inactivation Mechanism ◽

Macrophage Killing

Nearly all organisms found in nature have evolved and developed their own specific strategies to cope with reactive oxygen species (ROS). Catalase, a heme-containing tetramer protein expressed in a broad range of aerobic fungi, has been utilized as an essential enzymatic ROS detoxifying mechanism, and shows remarkable efficiency in degrading hydrogen peroxide (H2O2) for fungal cell survival and host invasion. Here, we demonstrate that catalase inactivation with blue light renders fungal cells highly susceptible to ROS attack, thus resembling a 'strength-to-weakness optical switch'. To unveil catalase as the underlying molecular target of blue light and its inactivation mechanism, we systematically compared wild-type Candida albicans to a catalase-deficient mutant strain for susceptibility to ROS in the absence/presence of 410 nm treatment. Upon testing on a wide range of fungal species and strains, we found that intracellular catalase could be effectively and universally inactivated by 410 nm blue light. We find that the photoinactivation of catalase in combination with ROS-generating agents is highly effective and potent in achieving full eradication of multiple fungal species and strains, including multiple clinical strains of Candida auris, the causative agent of the global fungal epidemic. In addition, photoinactivation of catalase is shown to facilitate macrophage killing of intracellular Candida albicans. The antifungal efficacy of catalase photoinactivation is further validated using a Candida albicans-induced mouse model of skin abrasion. Taken together, our findings offer a novel catalase-photoinactivation approach to address multidrug-resistant Candida infections.

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Eliciting antibiotics active against the ESKAPE pathogens in a collection of actinomycetes isolated from mountain soils

Microbiology ◽

10.1099/mic.0.078295-0 ◽

2014 ◽

Vol 160 (8) ◽

pp. 1714-1725 ◽

Cited By ~ 54

Author(s):

Hua Zhu ◽

Jasper Swierstra ◽

Changsheng Wu ◽

Geneviève Girard ◽

Young Hae Choi ◽

...

Keyword(s):

Growth Conditions ◽

Multidrug Resistant ◽

Antimicrobial Activities ◽

Clinical Isolates ◽

Qinling Mountains ◽

Major Threat ◽

Specific Pathogen ◽

Eskape Pathogens ◽

The Himalaya ◽

Rapid Emergence

The rapid emergence of multidrug-resistant (MDR) bacterial pathogens poses a major threat for human health. In recent years, genome sequencing has unveiled many poorly expressed antibiotic clusters in actinomycetes. Here, we report a well-defined ecological collection of >800 actinomycetes obtained from sites in the Himalaya and Qinling mountains, and we used these in a concept study to see how efficiently antibiotics can be elicited against MDR pathogens isolated recently from the clinic. Using 40 different growth conditions, 96 actinomycetes were identified – predominantly Streptomyces – that produced antibiotics with efficacy against the MDR clinical isolates referred to as ESKAPE pathogens: Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa and/or Enterobacter cloacae. Antimicrobial activities that fluctuated strongly with growth conditions were correlated with specific compounds, including borrelidin, resistomycin, carbomethoxy-phenazine, and 6,7,8- and 5,6,8-trimethoxy-3-methylisocoumarin, of which the latter was not described previously. Our work provided insights into the potential of actinomycetes as producers of drugs with efficacy against clinical isolates that have emerged recently and also underlined the importance of targeting a specific pathogen.

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Facile Bio-Fabrication of Ag-Cu-Co Trimetallic Nanoparticles and Its Fungicidal Activity against Candida auris

Journal of Fungi ◽

10.3390/jof7010062 ◽

2021 ◽

Vol 7 (1) ◽

pp. 62 ◽

Cited By ~ 1

Author(s):

Majid Rasool Kamli ◽

Vartika Srivastava ◽

Nahid H. Hajrah ◽

Jamal S. M. Sabir ◽

Khalid Rehman Hakeem ◽

...

Keyword(s):

Electron Microscopy ◽

Antimicrobial Properties ◽

Bloodstream Infections ◽

Multidrug Resistant ◽

Biologically Active ◽

Phase Cell ◽

Candida Auris ◽

Medical Problems ◽

One Pot ◽

X Ray

Candida auris is an emergent multidrug-resistant pathogen that can lead to severe bloodstream infections associated with high mortality rates, especially in hospitalized individuals suffering from serious medical problems. As Candida auris is often multidrug-resistant, there is a persistent demand for new antimycotic drugs with novel antifungal action mechanisms. Here, we reported the facile, one-pot, one-step biosynthesis of biologically active Ag-Cu-Co trimetallic nanoparticles using the aqueous extract of Salvia officinalis rich in polyphenols and flavonoids. These medicinally important phytochemicals act as a reducing agent and stabilize/capping in the nanoparticles’ fabrication process. Fourier Transform-Infrared, Scanning electron microscopy, Transmission Electron Microscopy, Energy dispersive X-Ray, X-ray powder diffraction and Thermogravimetric analysis (TGA) measurements were used to classify the as-synthesized nanoparticles. Moreover, we evaluated the antifungal mechanism of as-synthesized nanoparticles against different clinical isolates of C. auris. The minimum inhibitory concentrations and minimum fungicidal concentrations ranged from 0.39–0.78 μg/mL and 0.78–1.56 μg/mL. Cell count and viability assay further validated the fungicidal potential of Ag-Cu-Co trimetallic nanoparticles. The comprehensive analysis showed that these trimetallic nanoparticles could induce apoptosis and G2/M phase cell cycle arrest in C. auris. Furthermore, Ag-Cu-Co trimetallic nanoparticles exhibit enhanced antimicrobial properties compared to their monometallic counterparts attributed to the synergistic effect of Ag, Cu and Co present in the as-synthesized nanoparticles. Therefore, the present study suggests that the Ag-Cu-Co trimetallic nanoparticles hold the capacity to be a lead for antifungal drug development against C. auris infections.

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Cell Surface Expression of Nrg1 Protein in Candida auris

Journal of Fungi ◽

10.3390/jof7040262 ◽

2021 ◽

Vol 7 (4) ◽

pp. 262

Author(s):

Anuja Paudyal ◽

Govindsamy Vediyappan

Keyword(s):

Cell Surface ◽

Growth Conditions ◽

Zinc Ion ◽

Surface Proteins ◽

Cell Surface Expression ◽

Unexpected Finding ◽

Candida Auris ◽

Cell Surface Proteins ◽

Biofilm Growth

Candida auris is an emerging antifungal resistant human fungal pathogen increasingly reported in healthcare facilities. It persists in hospital environments, and on skin surfaces, and can form biofilms readily. Here, we investigated the cell surface proteins from C. auris biofilms grown in a synthetic sweat medium mimicking human skin conditions. Cell surface proteins from both biofilm and planktonic control cells were extracted with a buffer containing β-mercaptoethanol and resolved by 2-D gel electrophoresis. Some of the differentially expressed proteins were excised and identified by mass spectrometry. C. albicans orthologs Spe3p, Tdh3p, Sod2p, Ywp1p, and Mdh1p were overexpressed in biofilm cells when compared to the planktonic cells of C. auris. Interestingly, several proteins with zinc ion binding activity were detected. Nrg1p is a zinc-binding transcription factor that negatively regulates hyphal growth in C. albicans. C. auris does not produce true hypha under standard in vitro growth conditions, and the role of Nrg1p in C. auris is currently unknown. Western blot analyses of cell surface and cytosolic proteins of C. auris against anti-CalNrg1 antibody revealed the Nrg1p in both locations. Cell surface localization of Nrg1p in C. auris, an unexpected finding, was further confirmed by immunofluorescence microscopy. Nrg1p expression is uniform across all four clades of C. auris and is dependent on growth conditions. Taken together, the data indicate that C. auris produces several unique proteins during its biofilm growth, which may assist in the skin-colonizing lifestyle of the fungus during its pathogenesis.

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Candida auris and Carbapenemase-Producing Organism Prevalence in an Extended Stay Pediatric Hospital, Chicago, Illinois, 2019

Infection Control and Hospital Epidemiology ◽

10.1017/ice.2020.662 ◽

2020 ◽

Vol 41 (S1) ◽

pp. s145-s146

Author(s):

Kelly Walblay ◽

Tristan McPherson ◽

Elissa Roop ◽

David Soglin ◽

Ann Valley ◽

...

Keyword(s):

The United States ◽

Multidrug Resistant ◽

Pediatric Hospital ◽

Mechanical Ventilators ◽

Candida Auris ◽

Term Care ◽

Healthcare Settings ◽

High Acuity ◽

Gastrostomy Tubes

Background:Candida auris and carbapenemase-producing organisms (CPO) are multidrug-resistant organisms that can colonize people for prolonged periods and can cause invasive infections and spread in healthcare settings, particularly in high-acuity long-term care facilities. Point-prevalence surveys (PPSs) conducted in long-term acute-care hospitals in the Chicago region identified median prevalence of colonization to be 31% for C. auris and 24% for CPO. Prevalence of C. auris colonization has not been described in pediatric populations in the United States, and limited data exist on CPO colonization in children outside intensive care units. The Chicago Department of Public Health (CDPH) conducted a PPS to assess C. auris and CPO colonization in a pediatric hospital serving high-acuity patients with extended lengths of stay (LOS). Methods: CDPH conducted a PPS in August 2019 in a pediatric hospital with extended LOS to screen for C. auris and CPO colonization. Medical devices (ie, gastrostomy tubes, tracheostomies, mechanical ventilators, and central venous catheters [CVC]) and LOS were documented. Screening specimens consisted of composite bilateral axillae and groin swabs for C. auris and rectal swabs for CPO testing. The Wisconsin State Laboratory of Hygiene tested all specimens. Real-time polymerase chain reaction (PCR) assays were used to detect C. auris DNA and carbapenemase genes: blaKPC, blaNDM, blaVIM, blaOXA-48, and blaIMP (Xpert Carba-R Assay, Cepheid, Sunnyvale, CA). All axillae and groin swabs were processed by PCR and culture to identify C. auris. For CPO, culture was only performed on PCR-positive specimens. Results: Of the 29 patients hospitalized, 26 (90%) had gastrostomy tubes, 24 (83%) had tracheostomies, 20 (69%) required mechanical ventilation, and 3 (10%) had CVCs. Also, 25 (86%) were screened for C. auris and CPO; 4 (14%) lacked parental consent and were not swabbed. Two rectal specimens were unsatisfactory, producing invalid CPO test results. Median LOS was 35 days (range, 1–300 days). No patients were positive for C. auris. From CPO screening, blaOXA-48 was detected in 1 patient sample, yielding a CPO prevalence of 3.4% (1 of 29). No organism was recovered from the blaOXA-48 positive specimen. Conclusions: This is the first documented screening of C. auris colonization in a pediatric hospital with extended LOS. Despite a high prevalence of C. auris and CPOs in adult healthcare settings of similar acuity in the region, C. auris was not identified and CPOs were rare at this pediatric facility. Additional evaluations in pediatric hospitals should be conducted to further understand C. auris and CPO prevalence in this population.Funding: NoneDisclosures: None

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Biofilms as Promoters of Bacterial Antibiotic Resistance and Tolerance

Antibiotics ◽

10.3390/antibiotics10010003 ◽

2020 ◽

Vol 10 (1) ◽

pp. 3

Author(s):

Cristina Uruén ◽

Gema Chopo-Escuin ◽

Jan Tommassen ◽

Raúl C. Mainar-Jaime ◽

Jesús Arenas

Keyword(s):

Close Contact ◽

Animal Health ◽

Deep Understanding ◽

Growth Conditions ◽

Multidrug Resistant ◽

Extracellular Dna ◽

Resistant Bacteria ◽

Resistance To Antibiotics ◽

Global Threat ◽

Biofilm Development

Multidrug resistant bacteria are a global threat for human and animal health. However, they are only part of the problem of antibiotic failure. Another bacterial strategy that contributes to their capacity to withstand antimicrobials is the formation of biofilms. Biofilms are associations of microorganisms embedded a self-produced extracellular matrix. They create particular environments that confer bacterial tolerance and resistance to antibiotics by different mechanisms that depend upon factors such as biofilm composition, architecture, the stage of biofilm development, and growth conditions. The biofilm structure hinders the penetration of antibiotics and may prevent the accumulation of bactericidal concentrations throughout the entire biofilm. In addition, gradients of dispersion of nutrients and oxygen within the biofilm generate different metabolic states of individual cells and favor the development of antibiotic tolerance and bacterial persistence. Furthermore, antimicrobial resistance may develop within biofilms through a variety of mechanisms. The expression of efflux pumps may be induced in various parts of the biofilm and the mutation frequency is induced, while the presence of extracellular DNA and the close contact between cells favor horizontal gene transfer. A deep understanding of the mechanisms by which biofilms cause tolerance/resistance to antibiotics helps to develop novel strategies to fight these infections.

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Two Candida auris Cases in Germany with No Recent Contact to Foreign Healthcare—Epidemiological and Microbiological Investigations

Journal of Fungi ◽

10.3390/jof7050380 ◽

2021 ◽

Vol 7 (5) ◽

pp. 380

Author(s):

Joerg Steinmann ◽

Thomas Schrauzer ◽

Lisa Kirchhoff ◽

Jacques F. Meis ◽

Peter-Michael Rath

Keyword(s):

South Asian ◽

Multidrug Resistant ◽

Health Care Facilities ◽

Candida Auris ◽

Contact Precautions ◽

Asian Clade ◽

Care Facilities ◽

Long Time ◽

European Health ◽

Healthcare Associated

Candida auris has become a global fungal public health threat. This multidrug-resistant yeast is associated with nosocomial intra- and interhospital transmissions causing healthcare-associated infections. Here, we report on two C. auris cases from Germany. The two patients stayed in Germany for a long time before C. auris was detected during their hospitalization. The patients were isolated in single rooms with contact precautions. No nosocomial transmissions were detected within the hospital. Both C. auris isolates exhibited high minimum inhibitory concentrations (MICs) of fluconazole and one isolate additionally high MICs against the echinocandins. Microsatellite genotyping showed that both strains belong to the South Asian clade. These two cases are examples for appropriate in-hospital care and infection control without further nosocomial spread. Awareness for this emerging, multidrug-resistant pathogen is justified and systematic surveillance in European health care facilities should be performed.

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Antimicrobial Activities of Marine Sponge-Associated Bacteria

Microorganisms ◽

10.3390/microorganisms9010171 ◽

2021 ◽

Vol 9 (1) ◽

pp. 171

Author(s):

Yitayal S. Anteneh ◽

Qi Yang ◽

Melissa H. Brown ◽

Christopher M. M. Franco

Keyword(s):

Pathogenic Bacteria ◽

South Australia ◽

Multidrug Resistant ◽

Antimicrobial Activities ◽

Marine Sponges ◽

Bioactive Metabolites ◽

Human Pathogens ◽

Sponge Associated Bacteria ◽

Microbial Symbionts ◽

Bacteria And Fungi

The misuse and overuse of antibiotics have led to the emergence of multidrug-resistant microorganisms, which decreases the chance of treating those infected with existing antibiotics. This resistance calls for the search of new antimicrobials from prolific producers of novel natural products including marine sponges. Many of the novel active compounds reported from sponges have originated from their microbial symbionts. Therefore, this study aims to screen for bioactive metabolites from bacteria isolated from sponges. Twelve sponge samples were collected from South Australian marine environments and grown on seven isolation media under four incubation conditions; a total of 1234 bacterial isolates were obtained. Of these, 169 bacteria were tested in media optimized for production of antimicrobial metabolites and screened against eleven human pathogens. Seventy bacteria were found to be active against at least one test bacterial or fungal pathogen, while 37% of the tested bacteria showed activity against Staphylococcus aureus including methicillin-resistant strains and antifungal activity was produced by 21% the isolates. A potential novel active compound was purified possessing inhibitory activity against S. aureus. Using 16S rRNA, the strain was identified as Streptomyces sp. Our study highlights that the marine sponges of South Australia are a rich source of abundant and diverse bacteria producing metabolites with antimicrobial activities against human pathogenic bacteria and fungi.

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1579. Multidrug-Resistant Candida auris Isolates From New York Hospitals and Healthcare Facilities Are Susceptible to Antifungal Combinations

Open Forum Infectious Diseases ◽

10.1093/ofid/ofz360.1443 ◽

2019 ◽

Vol 6 (Supplement_2) ◽

pp. S576-S577

Author(s):

Brittany O’Brien ◽

Sudha Chaturvedi ◽

Vishnu Chaturvedi

Keyword(s):

New York ◽

Diagnostic System ◽

Multidrug Resistant ◽

Drug Combinations ◽

Antifungal Drugs ◽

Drug Resistant ◽

Candida Auris ◽

Current Case ◽

Healthcare Facilities ◽

Broth Microdilution Method

Abstract Background Candida auris outbreak continues unabated in New York with the current case counts exceeding 300 patients. We used a modification of standard CLSI broth microdilution method (BMD) if two-drug combinations are efficacious against C. auris isolates with high-resistance to fluconazole (FZ, MIC50 >256 mg/L), and variable resistance to other broad-spectrum antifungal drugs. Methods BMD plates were custom-designed and quality controlled by TREK Diagnostic System. The combination tests of 15 drug-resistant C. auris involved microtiter wells with the initial 144 two-drug combinations and their two-fold dilutions (1/2–1/32) to get 864 two-drug combinations finally. We utilized MIC100 endpoints for the drug combination readings as reported earlier for the intra- and inter-laboratory agreements obtained against Candida species and Aspergillus fumigatus (Antimicrob Agents Chemother. 2015. 59:1759–1766). We also tested minimum fungicidal concentrations (MFC). Results We tested all possible 864 two-drug antifungal combinations for nine antifungal drugs in use to yield 12,960 MIC100 readings, and MFC readings for 15 C. auris isolates. Flucytosine (FLC) at 2.0 mg/L potentiated most successful combinations with other drugs. Micafungin (MFG), Anidulafungin (AFG), Caspofungin (CAS) at individual concentrations of 0.25 mg/L combined well with FLC (2.0 mg/L) to yield MIC100 for 14, 13, and 12 of 15 C. auris isolates tested, respectively. MFG/FLC combination was also fungicidal for 4 of 15 isolates. AMB / FLC (0.25/1.0 mg/L) yielded MIC100 for 13 isolates and MFC for three test isolates. Posaconazole (POS), and Isavuconazole (ISA) and Voriconazole (VRC) also combined well with FLC (0.25/2.0 mg/L) to yield MIC100 for 12, 13, and 13 isolates, respectively. POS/FLC combination was fungicidal for three isolates. Conclusion We identified seven two drug-combinations of antifungals efficacious against drug-resistant C. auris strains. The modified BMD combination susceptibility testing could be used by the clinical laboratories to assist providers with the selection of optimal treatment for C. auris candidemia. Disclosures All authors: No reported disclosures.

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