Fungal Biofilms, Drug Resistance, and Recurrent Infection.

<p>A biofilm is a surface-associated microbial community. Diverse fungi are capable of biofilm growth. The significance of this growth form for infection biology is that biofilm formation on implanted devices is a major cause of recurrent infection. Biofilms also have limited drug susceptibility, making device-associated infection extremely difficult to treat. Biofilm-like growth can occur during many kinds of infection, even when an implanted device is not present. Here we summarize the current understanding of fungal biofilm formation, its genetic control, and the basis for biofilm drug resistance.</p

Fungal Matrix Polysaccharide Content and Function.

<p>Fungal Matrix Polysaccharide Content and Function.</p

Natural Product Disaccharide Engineering through Tandem Glycosyltransferase Catalysis Reversibility and Neoglycosylation

A two-step strategy for disaccharide modulation using vancomycin as a model is reported. The strategy relies upon a glycosyltransferase-catalyzed ‘reverse’ reaction to enable the facile attachment of an alkoxyamine-bearing sugar to the vancomycin core. Neoglycosylation of the corresponding aglycon led to a novel set of vancomycin 1,6-disaccharide variants. While the in vitro antibacterial properties of corresponding vancomycin 1,6-disaccharide analogs were equipotent to the parent antibiotic, the chemoenzymatic method presented is expected to be broadly applicable

Thalassosamide, a Siderophore Discovered from the Marine-Derived Bacterium <i>Thalassospira profundimaris</i>

Here we describe the rapid identification and prioritization of novel active marine natural products using an improved dereplication strategy. During the course of our screening of marine natural product libraries, a new cyclic trihydroxamate compound, thalassosamide, was discovered from the α-proteobacterium <i>Thalassospira profundimaris</i>. Its structure was determined by 2D NMR and MS/MS experiments, and the absolute configuration of the lysine-derived units was established by Marfey’s analysis, whereas that of C-9, 9′, and 9″ was determined via the circular dichroism data of the [Rh₂(OCOCF₃)₄] complex and DFT NMR calculations. Thalassosamide showed moderate in vivo efficacy against <i>Pseudomonas aeruginosa</i>

Synthesis and Antibacterial Activity of Doxycycline Neoglycosides

A set of 37 doxycycline neoglycosides were prepared, mediated via a C-9 alkoxyamino-glycyl-based spacer reminiscent of that of tigecycline. Subsequent <i>in vitro</i> antibacterial assays against representative drug-resistant Gram negative and Gram positive strains revealed a sugar-dependent activity profile and one doxycycline neoglycoside, the 2′-amino-α-d-glucoside conjugate, to rival that of the parent pharmacophore. In contrast, the representative tetracycline-susceptible strain <i>E. coli</i> 25922 was found to be relatively responsive to a range of doxycycline neoglycosides. This study also extends the use of aminosugars in the context of neoglycosylation via a simple two-step strategy anticipated to be broadly applicable for neoglycorandomization

Application of 3D NMR for Structure Determination of Peptide Natural Products

Despite the advances in NMR, structure determination is often slow and constitutes a bottleneck in natural products discovery. Removal of this bottleneck would greatly improve the throughput for antibiotic discovery as well as other therapeutic areas. Overall, faster structure methods for structure determination will serve the natural products community in a broad manner. This report describes the first application of 3D NMR for elucidation of two microbially produced peptide natural products with novel structures. The methods are cost-effective and greatly improve the confidence in a proposed structure

Variation in frequency of non-<i>albicans</i> species of <i>Candida</i> by geographic region.

<p>*hospitals designated by the letter ‘H’; and a number: H1, H2 etc.</p>†<p>other species includes: <i>C. kefyr</i> (nine isolates), <i>C. famata</i> (four isolates), <i>C. rugosa</i> (three isolates), <i>C. utilis</i> (two isolates) and one isolate each of <i>C. fennica</i>, <i>C. fermentati</i>, <i>C. lipolytica</i>, and <i>Torulopsis</i> spp.</p>§<p>multiple species include <i>C. parapsilosis+C. glabrata</i> (n = 30), <i>C. tropicalis+C. glabrata</i> (n = 21), <i>C. krusei+C. glabrata</i> (n = 8), <i>C. dubliniensis+C. glabrata</i> (n = 3), <i>C. lusitaniae+C. glabrata</i> (n = 4), other <i>Candida</i> spp.<i>+C. glabrata</i> (n = 3), unknown <i>Candida spp.+C. glabrata</i> (n = 3), <i>C. guilliermondii+C. glabrata</i> (n = 2), <i>C. parapsilosis+C. krusei</i> (n = 5), <i>C. lusitaniae+C. krusei</i> (n = 2), <i>C. tropicalis+C. dubliniensis</i> (n = 1), <i>C. tropicalis+C. guilliermondii</i> (n = 1), <i>C. tropicalis+C. krusei</i> (n = 4), other <i>Candida</i> spp.+<i>C.</i> guilliermondii (n = 1), unknown <i>Candida</i> spp.+C. <i>dubliniensis</i> (n = 1), <i>C. glabrata+C. krusei+C. lusitaniae</i> (n = 1), <i>C. dubliniensis+C. glabrata+C. guilliermondii</i> (n = 1).</p

Intraluminal Release of an Antifungal β‑Peptide Enhances the Antifungal and Anti-Biofilm Activities of Multilayer-Coated Catheters in a Rat Model of Venous Catheter Infection

Candida albicans is the most prevalent cause of hospital-acquired fungal infections and forms biofilms on indwelling medical devices that are notoriously difficult to treat or remove. We recently demonstrated that the colonization of C. albicans on the surfaces of catheter tube segments can be reduced in vitro by coating them with polyelectrolyte multilayers (PEMs) that release a potent antifungal β-peptide. Here, we report on the impact of polymer structure and film composition on both the inherent and β-peptide-mediated ability of PEM-coated catheters to prevent or reduce the formation of C. albicans biofilms in vitro and in vivo using a rat model of central venous catheter infection. Coatings fabricated using polysaccharide-based components [hyaluronic acid (HA) and chitosan (CH)] and coatings fabricated using polypeptide-based components [poly-l-lysine (PLL) and poly-l-glutamic acid (PGA)] both served as reservoirs for the loading and sustained release of β-peptide, but differed substantially in loading and release profiles and in their inherent antifungal properties (e.g., the ability to prevent colonization and biofilm growth in the absence of β-peptide). In particular, CH/HA films exhibited inherent antifungal and antibiofilm behaviors in vitro and in vivo, a result we attribute to the incorporation of CH, a weak polycation demonstrated to exhibit antimicrobial properties in other contexts. The antifungal properties of both types of films were improved substantially when β-peptide was incorporated. Catheter segments coated with β-peptide-loaded CH/HA and PLL/PGA films were both strongly antifungal against planktonic C. albicans and the formation of surface-associated biofilms in vitro and in vivo. Our results demonstrate that PEM coatings provide a useful platform for the design of new antifungal materials, and suggest opportunities to design multifunctional or dual-action platforms to prevent or reduce the severity of fungal infections in applied biomedical contexts or other areas in which fungal biofilms are endemic

90-day survival stratified by non-<i>albicans Candida</i> species.

<p>90-day survival stratified by non-<i>albicans Candida</i> species.</p

Antifungal treatment administered by species on infection day 3.

<p>*Other species includes: <i>C. kefyr</i> (nine isolates), <i>C. famata</i> (four isolates), <i>C. rugosa</i> (three isolates), <i>C. utilis</i> (two isolates) and one isolate each of <i>C. fennica</i>, <i>C. fermentati</i>, <i>C. lipolytica</i>, and <i>Torulopsis</i> spp.</p>†<p>multiple species include <i>C. parapsilosis+C. glabrata</i> (n = 30), <i>C. tropicalis+C. glabrata</i> (n = 21), <i>C. krusei+C. glabrata</i> (n = 8), <i>C. dubliniensis+C. glabrata</i> (n = 3), <i>C. lusitaniae+C. glabrata</i> (n = 4), other <i>Candida</i> spp.<i>+C. glabrata</i> (n = 3), unknown <i>Candida spp.+C. glabrata</i> (n = 3), <i>C. guilliermondii+C. glabrata</i> (n = 2), <i>C. parapsilosis+C. krusei</i> (n = 5), <i>C. lusitaniae+C. krusei</i> (n = 2), <i>C. tropicalis+C. dubliniensis</i> (n = 1), <i>C. tropicalis+C. guilliermondii</i> (n = 1), <i>C. tropicalis+C. krusei</i> (n = 4), other <i>Candida</i> spp.+<i>C.</i> guilliermondii (n = 1), unknown <i>Candida</i> spp.+C. <i>dubliensis</i> (n = 1), <i>C. glabrata+C. krusei+C. lusitaniae</i> (n = 1), <i>C. dubliniensis+C.glabrata+C.guilliermondii</i> (n = 1).</p>§<p>patients in this category were in a blinded clinical trial.</p>‡<p>Other combination therapies included lipid amphotericin B +5-fluorocytosine (n = 7), lipid amphotericin B+fluconazole (n = 10), amphotericin B deoxycholate+lipid amphotericin B (n = 1), amphotericin B deoxycholate+fluconazole (n = 2), echinocandins +5-fluorocytosine (n = 1), echinocandins+amphotericin B deoxycholate (n = 9), echinocandins+fluconazole (n = 1), echinocandins+itraconazole (n = 1), fluconazole+blinded (n = 1), fluconazole+voriconazole (n = 8).</p