A Comparative Study of the Effects of Intravitreal Anidulafungin, Voriconazole, and Amphotericin B in an Experimental Candida Endophthalmitis Model

Eye fungal infections: a mini review

Ocular fungal infections annually affect more than one million individuals worldwide. The management of these infections is problematic, mainly due to the limited availability of effective antifungal agents. Thus, ocular infections are increasingly recognized as important causes of morbidity and blindness, especially keratitis and endophthalmitis. Thus, this review aims to demonstrate the importance of fungal eye infections through the description of the main related aspects, with emphasis on the treatment of these infections. For this purpose, a search for scientific articles was conducted in databases, such as Medline, published from 2000 onwards, addressing important aspects involving fungal eye infections. In addition, this work highlighted the limited therapeutic arsenal available and the severity associated with these infections. Thus, highlighting the importance of constantly updating knowledge about these pathologies, as it contributes to agility in choosing the available and most appropriate therapeutic alternatives, aiming at positive and minimally harmful results for that particular patient.

Systemic Candida albicans Infection in Mice Causes Endogenous Endophthalmitis via Breaching the Outer Blood-Retinal Barrier

Candida albicans is the leading cause of endogenous fungal endophthalmitis; however, its pathobiology studies are limited. Moreover, the contribution of host factors in the pathogenesis of Candida endophthalmitis remains unclear. In the present study, we developed a murine model of C. albicans endogenous endophthalmitis and investigated the molecular pathobiology of ocular candidiasis and blood-retinal barrier permeability. Our data show that intravenous injection of C. albicans in immunocompetent C57BL/6 mice led to endogenous endophthalmitis without causing mortality, and C. albicans was detected in the eyes at 3 days postinfection and persisted for up to 10 days. The intraocular presence of C. albicans coincided with a decrease in retinal function and increased expression of inflammatory mediators (tumor necrosis factor alpha [TNF-α], interleukin 1β [IL-1β], MIP2, and KC) and antimicrobial peptides (human β-defensins [hBDs] and LL37) in mouse retinal tissue. C. albicans infection disrupted the blood-retinal barrier (BRB) by decreasing the expression of tight junction (ZO-1) and adherens junction (E-cadherin, N/R-cadherin) proteins. In vitro studies using human retinal pigment epithelial (ARPE-19) cells showed time-dependent activation of eIF2α, extracellular signal-related kinase (ERK), and NF-κB signaling and decreased activity of AMP-activated protein kinase (AMPK) leading to the induction of an inflammatory response upon C. albicans infection. Moreover, C. albicans-infected cells exhibited increased cellular permeability coinciding with a reduction in cellular junction proteins. Overall, our study provides new insight into the molecular pathogenesis of C. albicans endogenous endophthalmitis. Furthermore, the experimental models developed in the study can be used to identify newer therapeutic targets or test the efficacy of drugs to treat and prevent fungal endophthalmitis. IMPORTANCE Patients with candidemia often experience endophthalmitis, a blinding infectious eye disease. However, the pathogenesis of Candida endophthalmitis is not well understood. Here, using in vivo and in vitro experimental models, we describe events leading to the invasion of Candida into the eye. We show that Candida from the systemic circulation disrupts the protective blood-retinal barrier and causes endogenous endophthalmitis. Our study highlights an important role of retinal pigment epithelial cells in evoking innate inflammatory and antimicrobial responses toward C. albicans infection. This study allows a better understanding of the pathobiology of fungal endophthalmitis, which can lead to the discovery of novel therapeutic targets to treat ocular fungal infections.

Therapeutic innovation for multi-resistant candidemics: Synergy of isavuconazole and caspofungin association

Fungal infections occurring in immunocompromised patients after immunochemotherapy treatment are often difficult to eradicate and capable of even being fatal. Systemic mycoses affecting severely immunocompromised patients often manifest acutely with rapidly progressive pneumonia, fungemia, or manifestations of extrapulmonary dissemination. Opportunistic fungal infections (mycoses) include several pathogens elements, as candidiasis, aspergillosis, mucormycosis (zygomycosis) and fusariosis. Prompt diagnosis and effective therapy are needed to improve the associated morbidity and mortality, especially in cases with non-canonical fungal localizations and not responsive to the available antifungal drugs.

Underlying mechanisms of the effect of minocycline against Candida albicans biofilms

Minocycline (MH) is a broad-spectrum antimicrobial agent and semisynthetic tetracycline derivative, which has been widely used in the clinic due to its efficacy. Having the strongest anti-microbial effect, MH exceeded the traditional scope of antibiotics and its previously unknown antifungal activity is also gradually being discovered. To preliminarily investigate the inhibitory effect of MH on Candida albicans (C. albicans), changes of cell growth, hyphal formation and transition, biofilm production and signaling pathway gene expression of C. albicans in the presence of MH were assessed in the present study. An XTT reduction assay was performed to quantitatively detect the metabolic activity of biofilms and evaluate the inhibition of MH on this. The results suggested that biofilm formation was clearly inhibited by 67% (P<0.0001) in the presence of 250 µg/ml MH, while mature biofilms were not significantly affected. In addition, MH inhibited the transition from yeast to hypha in a dose-dependent manner. Furthermore, reverse transcription-quantitative PCR revealed that several hyphae- and adhesion-specific genes associated with the Ras/cyclic (c)AMP/protein kinase A (PKA) pathway were differentially expressed following MH treatment, including downregulation of ras family GTPase (RAS1), adenylyl cyclase-associated protein 1 (CAP1), thiamin pyrophosphokinase 1 (TPK1), adenylate cyclase (CDC35), transcription factor (TEC1), agglutinin-like protein 3 (ALS3) and hyphal wall protein 1 (HWP1) and upregulation of EFG1 (enhanced filamentous growth protein 1 gene) and PDE2 (high-affinity phosphodiesterase gene). The most obviously changed genes were TPK1, HWP1 and RAS1, downregulated by 0.33-, 0.48- and 0.55-fold, respectively. It was suggested that MH is associated with alterations in the morphology of C. albicans, such as the repression of hypha and biofilm formation of cells, and MH affected the Ras/cAMP pathway to regulate the expression of cAMP-associated genes.

Vitrectomy combined with intravitreal antifungal therapy for posttraumatic fungal endophthalmitis in eastern China

Background

To evaluate the effect and prognostic factors of vitrectomy combined with intravitreal antifungal therapy for posttraumatic fungal endophthalmitis in Eastern China.

Methods

We retrospectively reviewed the medical records of patients who developed fungal endophthalmitis after penetrating ocular trauma at an ophthalmic center in Eastern China. All patients underwent vitrectomy and intravitreal injection of antifungal drugs.

Results

Thirty-five patients (35 eyes) were included. Twelve eyes suffered plant trauma, 17 eyes metal trauma, and 6 eyes other trauma. The culture results for all 35 eyes showed filamentous fungi, including Aspergillus in 26 eyes (74.3%). Twenty-three eyes underwent vitrectomy once and 12 eyes were treated twice. Four eyes were iridectomized because of a fungal lesion behind the iris. Fungal endophthalmitis was effectively controlled in 33 eyes (94.3%), whereas 2 eyes were ultimately enucleated. Visual acuity was significantly better after treatment than before treatment (P = 0.0006). According to the preoperative vision, the affected eyes were divided into two groups: group 1A (light perception) and group 1B (better than light perception). The final visual acuity in group 1B was significantly better than that in group 1A (P = 0.0289).

Conclusions

Vitrectomy combined with intravitreal antifungal therapy is an effective treatment for posttraumatic fungal endophthalmitis. Preoperative visual acuity is a significant factor affecting the prognosis of visual acuity.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12886-020-01703-7.

Echinocandins: Their role in the management of Candida biofilms

The importance of antifungal agents and their clinical implications has received little attention in comparison to antibiotics, particularly in the health-care setting. However, apart from bacterial infections rising in hospitals, the incidences of fungal infections are growing with the development of resistance to conventional antifungal agents. Newer antifungal agents such as echinocandins (ECs) have been extensively studied over the past decade and are recognised as a superior treatment compared with prior antifungals as a first line of therapy in tertiary institutions. Caspofungin (CAS), micafungin (MICA) and anidulafungin (ANID) are the three most widely used EC antifungal agents. The treatment of biofilm-associated fungal infections affecting patients in tertiary health-care facilities has been identified as a challenge, particularly in Indian Intensive Care Unit (ICU) settings. With the rising number of critically ill patients requiring invasive devices such as central venous catheters for treatment, especially in ICUs, these devices serve as a potential source of nosocomial infections. Candida spp. colonisation is a major precursor of these infections and further complicates and prolongs treatment procedures, adding to increasing costs both for hospitals and the patient. Analysing studies involving the use of these agents can help in making critical decisions for antifungal therapy in the event of a fungal infection in the ICU. In addition, the development of resistance to antifungal agents is a crucial factor for assessing the appropriate antifungals that can be used for treatment. This review provides an overview of ANID in biofilms, along with CAS and MICA, in terms of clinical efficacy, resistance development and potency, primarily against Candida spp.