Successful therapy of progressive rhino-orbital mucormycosis caused by Rhizopus arrhizus with combined and sequential antifungal therapy, surgery and hyperbaric therapy

Hyperbaric oxygen in the management of wound tissue necrosis after external dacrocystorhinostomy

Hyperbaric oxygen is an adjunctive treatment for promoting wound healing and reducing infection. We present an unusual case of wound tissue necrosis occurring after external dacryocystorhinostomy (ExtDCR) that was subsequently treated with hyperbaric oxygen (HBO) and advancement flaps with good outcome. HBO improves vascularization of ischemic tissues after ExtDCR for greater success after reconstructive surgery.

Breaking the Mold

Objective: To review the current literature for the pathogenesis of mucormycosis, discuss diagnostic strategies, and evaluate the efficacy of polyenes, triazoles, and echinocandins as pharmacological treatment options. Data Sources: An electronic literature search was conducted in PubMed using the MESH terms Rhizopus, zygomycetes, zygomycosis, Mucorales and mucormycosis, with search terms amphotericin B, micafungin, anidulafungin, caspofungin, extended infusion amphotericin B, liposomal amphotericin B, combination therapy, triazole, posaconazole, isavuconazole, diagnosis, and clinical manifestations.Study Selection and Data Extraction: Studies written in the English language from January 1960 to March 2016 were considered for this review article. All search results were reviewed, and the relevance of each article was determined by the authors independently. Data Synthesis: Mucormycosis is a rare invasive fungal infection with an exceedingly high mortality and few therapeutic options. It has a distinct predilection for invasion of endothelial cells in the vascular system, which is likely important in dissemination of disease from a primary focus of infection. Six distinct clinical syndromes can occur in susceptible hosts, including rhino-orbital-cerebral, pulmonary, gastrointestinal, cutaneous, widely disseminated, and miscellaneous infection. Conclusion: Diagnosis of mucormycosis is typically difficult to make based on imaging studies, sputum culture, bronchoalveolar lavage culture, or needle aspirate. Surgical debridement prior to dissemination of infection improves clinical outcomes. Surgery combined with early, high-dose systemic antifungal therapy yields greater than a 1.5-fold increase in survival rates. The Mucorales are inherently resistant to most widely used antifungal agents. Amphotericin B is appropriate for empirical therapy, whereas posaconazole and isavuconazole are best reserved for de-escalation, refractory cases, or patients intolerant to amphotericin B.

Bicarbonate correction of ketoacidosis alters host-pathogen interactions and alleviates mucormycosis

Patients with diabetic ketoacidosis (DKA) are uniquely predisposed to mucormycosis, an angioinvasive fungal infection with high mortality. Previously, we demonstrated that Rhizopus invades the endothelium via binding of fungal CotH proteins to the host receptor GRP78. Here, we report that surface expression of GRP78 is increased in endothelial cells exposed to physiological concentrations of β-hydroxy butyrate (BHB), glucose, and iron that are similar to those found in DKA patients. Additionally, expression of R. oryzae CotH was increased within hours of incubation with DKA-associated concentrations of BHB, glucose, and iron, augmenting the ability of R. oryzae to invade and subsequently damage endothelial cells in vitro. BHB exposure also increased fungal growth and attenuated R. oryzae neutrophil-mediated damage. Further, mice given BHB developed clinical acidosis and became extremely susceptible to mucormycosis, but not aspergillosis, while sodium bicarbonate reversed this susceptibility. BHB-related acidosis exerted a direct effect on both GRP78 and CotH expression, an effect not seen with lactic acidosis. However, BHB also indirectly compromised the ability of transferrin to chelate iron, as iron chelation combined with sodium bicarbonate completely protected endothelial cells from Rhizopus-mediated invasion and damage. Our results dissect the pathogenesis of mucormycosis during ketoacidosis and reinforce the importance of careful metabolic control of the acidosis to prevent and manage this infection.

Comparison of clinical pharmacology of voriconazole and posaconazole

Despite greater knowledge and possibilities in pharmacotherapy, fungal infections remain a challenge for clinicians. As the population of immunocompromised patients and those treated for their hematologic ailments increases, the number of fungal infections grows too. This is why there is still a quest for new antifungal drugs as well as for optimization of pharmacotherapy with already registered pharmaceutics.

Voriconazole and posaconazole are broad-spectrum, new generation, triazole antifungal agents. The drugs are used in the pharmacotherapy of invasive aspergillosis, Candida and Fusarium infections. Voriconazole is also used in infections caused by Scedosporium. Posaconazole is used in the treatment of coccidioidomycosis and chromoblastomycosis. Besides some similarities, the two mentioned drugs also show differences in therapeutic indications, pharmacokinetics (mainly absorption and metabolism), frequency and severity of adverse drug reactions, drug–drug interactions and dosage. As both of the drugs are used in the treatment of invasive fungal infections in adults and children, detailed knowledge of the clinical pharmacology of antifungal agents is the main factor in pharmacotherapy optimization in treatment of fungal infections.

The goal of the article is to present and compare the clinical pharmacology of voriconazole and posaconazole as well as to point out the indications and contraindications of using the drugs, determine factors influencing their pharmacotherapy, and provide information that might be helpful in the treatment of fungal infections.