The catheterized bladder environment promotes Efg1- and Als1-dependent Candida albicans infection

The Orientation of Human Fibrinogen at Biomedically Relevant Polydimethylsiloxane-Water Interfaces

The adsorption of fibrinogen on biomaterial surfaces, particularly polydimethylsiloxane (PDMS), plays a key role in foreign body reactions and has recently been shown to be one of the main factors driving catheter-associated urinary tract infections (CAUTIs). Yet, despite detailed studies on the fibrinogen's solution and crystal structures, its behavior at material interfaces is less understood. Using sum frequency generation (SFG) spectroscopy and structural modeling, we determined the binding pose and conformation of human fibrinogen at the PDMS-buffer interface. Fibrinogen adopts an upright orientation on PDMS with minimal bending. Comparisons with spectra recorded at the air-water interface and literature data on polystyrene reveal significant differences in orientation: fibrinogen binds flat and bent at these model hydrophobic interfaces, while upright conformations are observed on liquid PDMS. These findings demonstrate specific interaction beyond simple hydrophobic attraction at the PDMS interface and hint at the critical role of surface chemistry in dictating fibrinogen's interfacial structure and its implications for biomaterial design aimed at reducing foreign body reactions and CAUTIs.

Candida auris is emerging as a prevalent urinary pathogen

Urinary tract infections (UTIs) are one of the most common infections, with a subgroup of these infections, catheter-associated UTIs (CAUTIs), accounting for 40% of nosocomial infections. While the majority of CAUTI pathogens are bacterial, the second most common pathogen is the fungus Candida albicans. However, in recent years, Candida auris has increasingly been isolated from urine, indicating C. auris' potential as a urinary pathogen. C. auris has rapidly emerged as a human pathogen worldwide, becoming a serious health threat. This is of great concern due to its antifungal resistance, adherence to inanimate surfaces, high mortality rates, and the extensive knowledge gap regarding C. auris' prevalence and pathophysiology. To understand whether C. auris is prevalent in the urinary tract, we analyzed 12,996 C. auris clinical strains and their frequency related to urine and urinary catheters. We identified urine as the second most common C. auris isolation source in the United States and the third most common worldwide. Anecdotally, C. auris urine isolates are often associated with urinary catheters and high mortality rates. Furthermore, there has been an early indication of urinary isolates developing echinocandin resistance. With the increasing incidence of uropathogenic C. auris, it is critical to have an in-depth understanding of C. auris pathogenesis in the urinary tract to effectively prevent and treat these infections.

The antibiofilm potential of Clidemia hirta against Candida albicans: preliminary study

OBJECTIVE

This study aims to screen the activity of ethanol extract of Clidemia hirta fruits and leaves against 24 h old Candida albicans biofilm by measuring cell viability with 3-(4,5-dimethylthiazol- 2-yl)- 2,5-diphenyl tetrazolium bromide (MTT) and planktonic cells of C. albicans using the broth microdilution method.

RESULTS

The ethanol extract of C. hirta fruits inhibited (50%) the C. albicans biofilm at a concentration fourfold higher than those required to inhibit planktonic cells (31.25 µg/mL vs. 7.8 µg/mL). This finding is supported by the morphological changes of C. albicans biofilm under scanning electron microscopy (SEM) visualization. A total of 55 compounds were detected using UHPLC coupled with Thermo Scientific™ Q Exactive™ High-Resolution Mass Spectrometer (HRMS). The top three compounds of the ethanol extract: dodecyl sulfate, bis(2-ethylhexyl) phthalate, and erucamide) might be responsible compounds for the antibiofilm activity of ethanol extract of C. hirta.

Bacterial adhesion strategies and countermeasures in urinary tract infection

Urinary tract infections (UTIs) are compounded by antimicrobial resistance, which increases the risk of UTI recurrence and antibiotic treatment failure. This also intensifies the burden of disease upon healthcare systems worldwide, and of morbidity and mortality. Uropathogen adhesion is a critical step in the pathogenic process, as has been mainly shown for Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae, Streptococcus agalactiae, Proteus, Enterococcus and Staphylococcus species. Although many bacterial adhesion molecules from these uropathogens have been described, our understanding of their contributions to UTIs is limited. Here we explore knowledge gaps in the UTI field, as we discuss the broader repertoire of uropathogen adhesins, including their role beyond initial attachment and the counter-responses of the host immune system. Finally, we describe the development of therapeutic approaches that target uropathogenic adhesion strategies and provide potential alternatives to antibiotics.

2-Chloromethyl anthraquinone inhibits Candida albicans biofilm formation by inhibiting the Ras1-cAMP-Efg1 pathway

Candida albicans is an opportunistic pathogen, and the formation of its biofilm makes it resistant to traditional antifungal therapy. Anthraquinones have universal antibacterial activity. We evaluated the inhibitory effects of 2-chloromethyl anthraquinone on C. albicans adhesion, mycelial morphology transformation, and biofilm formation. The results showed that 2-chloromethyl anthraquinone could inhibit C. albicans adhesion, mycelium formation, and biofilm formation in a dose-dependent manner at 2 μg/mL. In addition, 2-chloromethyl anthraquinone significantly inhibited the expression of biofilm formation-related genes in C. albicans, including ALS1, CPH1, ECE1, HWP1, TEC1, BCR1, and UME6. In addition, Ras1-cAMP-Efg1 pathway-related genes (RAC1, CYR1, and TPK2) were also significantly down-regulated, indicating that the inhibitory effect of 2-chloromethyl anthraquinone on C. albicans biofilms may be related to the Ras1-cAMP-Efg1 signaling pathway. In summary, the results of this study confirmed the inhibitory mechanism of 2-chloromethyl anthraquinone on the virulence factors of C. albicans, which laid a theoretical foundation for its use as an anti-biofilm agent against C. albicans.

Urinary tract infections: pathogenesis, host susceptibility and emerging therapeutics

Urinary tract infections (UTIs), which include any infection of the urethra, bladder or kidneys, account for an estimated 400 million infections and billions of dollars in health-care spending per year. The most common bacterium implicated in UTI is uropathogenic Escherichia coli, but diverse pathogens including Klebsiella, Enterococcus, Pseudomonas, Staphylococcus and even yeast such as Candida species can also cause UTIs. UTIs occur in both women and men and in both healthy and immunocompromised patients. However, certain patient factors predispose to disease: for example, female sex, history of prior UTI, or the presence of a urinary catheter or other urinary tract abnormality. The current clinical paradigm for the treatment of UTIs involves the use of antibiotics. Unfortunately, the efficacy of this approach is dwindling as the prevalence of antimicrobial resistance rises among UTI isolates, and the immense quantity of antibiotics prescribed annually for these infections contributes to the emergence of resistant pathogens. Therefore, there is an urgent need for new antibiotics and non-antibiotic treatment and prevention strategies. In this Review, we discuss how recent studies of bacterial pathogenesis, recurrence, persistence, host-pathogen interactions and host susceptibility factors have elucidated new and promising targets for the treatment and prevention of UTIs.

A stable dual functional superhydrophobic coating to inhibit Proteus mirabilis colonization, migration, and encrustation formation for urinary catheter applications

Catheter-associated urinary tract infections are some of the most common hospital-acquired infections. Proteus mirabilis, a common pathogen associated with urinary tract infections, has swarming motility and has pili on its surface for adhesion and flagella for upward movement. Migration of P. mirabilis along the catheter surface can lead to ascending urinary tract infection. However, there is currently a lack of effective strategies to inhibit or delay the colonization, migration, and encrustation formation of P. mirabilis in urinary catheters. This study developed a method for constructing a stable superhydrophobic coating on the surface of urinary catheters using a layer-by-layer approach. The adhesion and deposition of polydopamine were enhanced by pre-coating a liquid bandage film on the polydimethylsiloxane surface, resulting in a multilayer micro-nano composite structure on the catheter surface. This structure was combined with copper ions and superhydrophobic modifiers, ultimately resulting in a highly stable superhydrophobic coating. The coating retains its superhydrophobic properties after prolonged incubation, friction tests, and tape peeling tests. Importantly, the coating demonstrates excellent efficacy in inhibiting P. mirabilis colonization, migration, and encrustation formation. This study offers novel insights into developing biomedical superhydrophobic coatings with enhanced stability and efficacy in inhibiting urinary tract bacterial infections.

Macrophage fate: to kill or not to kill?

Macrophages are dynamic innate immune cells that either reside in tissue, serving as sentinels, or recruited as monocytes from bone marrow into inflamed and infected tissue. In response to cues in the tissue microenvironment (TME), macrophages polarize on a continuum toward M1 or M2 with diverse roles in progression and resolution of disease. M1-like macrophages exhibit proinflammatory functions with antimicrobial and anti-tumorigenic activities, while M2-like macrophages have anti-inflammatory functions that generally resolve inflammatory responses and orchestrate a tissue healing process. Given these opposite phenotypes, proper spatiotemporal coordination of macrophage polarization in response to cues within the TME is critical to effectively resolve infectious disease and regulate wound healing. However, if this spatiotemporal coordination becomes disrupted due to persistent infection or dysregulated coagulation, macrophages' inappropriate response to these cues will result in the development of diseases with clinically unfavorable outcomes. Since plasticity and heterogeneity are hallmarks of macrophages, they are attractive targets for therapies to reprogram toward specific phenotypes that could resolve disease and favor clinical prognosis. In this review, we discuss how basic science studies have elucidated macrophage polarization mechanisms in TMEs during infections and inflammation, particularly coagulation. Therefore, understanding the dynamics of macrophage polarization within TMEs in diseases is important in further development of targeted therapies.

Hemiprotonic ph-ph+ with two targets inhibits metastatic breast cancer and concurrent candidiasis

Concurrent infection in breast cancer patients is the direct cause of the high mortality rate of the disease. However, there is no available method to increase the survival rate until now. To address the problem, we propose one drug with two target strategy to treat the refractory disease. A small chemical, ph-ph+, was attempted to be used in the study to explore the feasibility of the approach in anticancer and antifungus at the same time. The results showed that ph-ph+ could prevent the proliferation and metastasis of breast cancer cells, and kill C. albicans simultaneously. The molecular mechanism was associated with the activation of an evolutionarily conserved protease CLpP in the cancer and C. albicans cells. Also, the signaling pathway mediated by PLAGL2 that highly expressed in cancer cells participated in preventing cell metastasis and inducing apoptosis of ph-ph+. The one drug with dual targets inhibited the growth and metastasis of the cancer cells, and meanwhile eliminated C. albicans in tissues in the experimental animals. The results suggested that ph-ph+ with dual targets of CLpP and PLAGL2 would be a feasible approach to prolong the survival rate in patients with metastatic breast cancer and pathogenic infection.

Blunted blades: new CRISPR-derived technologies to dissect microbial multi-drug resistance and biofilm formation

The spread of multi-drug-resistant (MDR) pathogens has rapidly outpaced the development of effective treatments. Diverse resistance mechanisms further limit the effectiveness of our best treatments, including multi-drug regimens and last line-of-defense antimicrobials. Biofilm formation is a powerful component of microbial pathogenesis, providing a scaffold for efficient colonization and shielding against anti-microbials, which further complicates drug resistance studies. Early genetic knockout tools didn't allow the study of essential genes, but clustered regularly interspaced palindromic repeat inference (CRISPRi) technologies have overcome this challenge via genetic silencing. These tools rapidly evolved to meet new demands and exploit native CRISPR systems. Modern tools range from the creation of massive CRISPRi libraries to tunable modulation of gene expression with CRISPR activation (CRISPRa). This review discusses the rapid expansion of CRISPRi/a-based technologies, their use in investigating MDR and biofilm formation, and how this drives further development of a potent tool to comprehensively examine multi-drug resistance.

Fibrinolytic-deficiencies predispose hosts to septicemia from a catheter-associated UTI

Catheter-associated urinary tract infections (CAUTIs) are amongst the most common nosocomial infections worldwide and are difficult to treat partly due to development of multidrug-resistance from CAUTI-related pathogens. Importantly, CAUTI often leads to secondary bloodstream infections and death. A major challenge is to predict when patients will develop CAUTIs and which populations are at-risk for bloodstream infections. Catheter-induced inflammation promotes fibrinogen (Fg) and fibrin accumulation in the bladder which are exploited as a biofilm formation platform by CAUTI pathogens. Using our established mouse model of CAUTI, here we identified that host populations exhibiting either genetic or acquired fibrinolytic-deficiencies, inducing fibrin deposition in the catheterized bladder, are predisposed to severe CAUTI and septicemia by diverse uropathogens in mono- and poly-microbial infections. Furthermore, here we found that Enterococcus faecalis, a prevalent CAUTI pathogen, uses the secreted protease, SprE, to induce fibrin accumulation and create a niche ideal for growth, biofilm formation, and persistence during CAUTI.

Functional genetic characterization of stress tolerance and biofilm formation in Nakaseomyces (Candida) glabrata via a novel CRISPR activation system

The overexpression of genes frequently arises in Nakaseomyces (formerly Candida) glabrata via gain-of-function mutations, gene duplication, or aneuploidies, with important consequences on pathogenesis traits and antifungal drug resistance. This highlights the need to develop specific genetic tools to mimic and study genetic amplification in this important fungal pathogen. Here, we report the development, validation, and applications of the first clustered regularly interspaced short palindromic repeats (CRISPR) activation (CRISPRa) system in N. glabrata for targeted genetic overexpression. Using this system, we demonstrate the ability of CRISPRa to drive high levels of gene expression in N. glabrata, and further assess optimal guide RNA targeting for robust overexpression. We demonstrate the applications of CRISPRa to overexpress genes involved in fungal pathogenesis and drug resistance and detect corresponding phenotypic alterations in these key traits, including the characterization of novel phenotypes. Finally, we capture strain variation using our CRISPRa system in two commonly used N. glabrata genetic backgrounds. Together, this tool will expand our capacity for functional genetic overexpression in this pathogen, with numerous possibilities for future applications.IMPORTANCENakaseomyces (formerly Candida) glabrata is an important fungal pathogen that is now the second leading cause of candidiasis infections. A common strategy that this pathogen employs to resist antifungal treatment is through the upregulation of gene expression, but we have limited tools available to study this phenomenon. Here, we develop, optimize, and apply the use of CRISPRa as a means to overexpress genes in N. glabrata. We demonstrate the utility of this system to overexpress key genes involved in antifungal susceptibility, stress tolerance, and biofilm growth. This tool will be an important contribution to our ability to study the biology of this important fungal pathogen.

Fibrinolytic-deficiencies predispose hosts to septicemia from a catheter-associated UTI

Catheter-associated urinary tract infections (CAUTIs) are amongst the most common nosocomial infections worldwide and are difficult to treat due to multi-drug resistance development among the CAUTI-related pathogens. Importantly, CAUTI often leads to secondary bloodstream infections and death. A major challenge is to predict when patients will develop CAUTIs and which populations are at-risk for bloodstream infections. Catheter-induced inflammation promotes fibrinogen (Fg) and fibrin accumulation in the bladder which are exploited as a biofilm formation platform by CAUTI pathogens. Using our established mouse model of CAUTI, we identified that host populations exhibiting either genetic or acquired fibrinolytic-deficiencies, inducing fibrin deposition in the catheterized bladder, are predisposed to severe CAUTI and septicemia by diverse uropathogens in mono- and poly-microbial infections. Furthermore, we found that E. faecalis, a prevalent CAUTI pathogen, uses the secreted protease, SprE, to induce fibrin accumulation and create a niche ideal for growth, biofilm formation, and persistence during CAUTI.

Fungal mechanisms of intracellular survival: what can we learn from bacterial pathogens?

Fungal infections represent a major, albeit neglected, public health threat with serious medical and economic burdens globally. With unacceptably high mortality rates, invasive fungal pathogens are responsible for millions of deaths each year, with a steadily increasing incidence primarily in immunocompromised individuals. The poor therapeutic options and rise of antifungal drug resistance pose further challenges in controlling these infections. These fungal pathogens have adapted to survive within mammalian hosts and can establish intracellular niches to promote survival within host immune cells. To do that, they have developed diverse methods to circumvent the innate immune system attack. This includes strategies such as altering their morphology, counteracting macrophage antimicrobial action, and metabolic adaptation. This is reminiscent of how bacterial pathogens have adapted to survive within host cells and cause disease. However, relative to the great deal of information available concerning intracellular bacterial pathogenesis, less is known about the mechanisms fungal pathogens employ. Therefore, here we review our current knowledge and recent advances in our understanding of how fungi can evade and persist within host immune cells. This review will focus on the major fungal pathogens, including Cryptococcus neoformans, Candida albicans, and Aspergillus fumigatus, among others. As we discover and understand the strategies used by these fungi, similarities with their bacterial counterparts are becoming apparent, hence we can use the abundant information from bacteria to guide our studies in fungi. By understanding these strategies, new lines of research will open that can improve the treatments of these devastating fungal diseases.