Atypical Cutaneous Blastomycosis in a Child With Juvenile Idiopathic Arthritis on Infliximab

How Environmental Fungi Cause a Range of Clinical Outcomes in Susceptible Hosts

Environmental fungi are globally ubiquitous and human exposure is near universal. However, relatively few fungal species are capable of infecting humans, and among fungi, few exposure events lead to severe systemic infections. Systemic infections have mortality rates of up to 90%, cost the US healthcare system $7.2 billion annually, and are typically associated with immunocompromised patients. Despite this reputation, exposure to environmental fungi results in a range of outcomes, from asymptomatic latent infections to severe systemic infection. Here we discuss different exposure outcomes for five major fungal pathogens: Aspergillus, Blastomyces, Coccidioides, Cryptococcus, and Histoplasma species. These fungi include a mold, a budding yeast, and thermal dimorphic fungi. All of these species must adapt to dramatically changing environments over the course of disease. These dynamic environments include the human lung, which is the first exposure site for these organisms. Fungi must defend themselves against host immune cells while germinating and growing, which risks further exposing microbe-associated molecular patterns to the host. We discuss immune evasion strategies during early infection, from disruption of host immune cells to major changes in fungal cell morphology.

Opportunistic fungal infection in children and management

PURPOSE OF REVIEW

An opportunistic mycosis is a fungal agent of low pathogenicity that specifically infects immunocompromised hosts. Advances in transplantation, preterm care, immunosuppressive therapies and intensive care, have lead to the emergence of pediatric patients with serious immunodeficiency who are vulnerable to nonpathogenic fungi.

RECENT FINDINGS

The advent of the use of biologic agents in pediatric disease as well as the advances in care of preterm and immunosuppressed patients opens up a new cohort of patients at risk of opportunistic mycotic infections. Recent cases of cutaneous histioplasmosis as the presenting sign of hyper-IgM syndrome and the case of cutaneous blastomycosis in a patient treated with infliximab underscore the need to have a high clinical suspicion for deep fungal infections in immunosuppressed patients.

SUMMARY

The current review will focus on the cutaneous manifestations of cutaneous infections by Aspergillus, Blastomyces, histoplasmosis, and mucormycosis. Greater understanding of these diseases and high-quality research in identification and treatment can enhance care of patients in the coming future.

Infections in Children on Biologics

Biologics target various pathways to modify immunologic activity. Biologic use to treat pediatric patients continues to expand; but limited data exist regarding infectious complications of these agents, especially for newer agents. Infectious events reported in the literature for pediatric patients indicate that a variety of bacterial, mycobacterial, viral, and fungal infections can occur. Further pediatric-specific reports are needed to fill knowledge gaps in the complications related to these agents.

Clinical Manifestations and Treatment of Blastomycosis

The causal agents of blastomycosis, Blastomyces dermatitidis and Blastomyces gilchristii, belong to a group of thermally dimorphic fungi that can infect healthy and immunocompromised individuals. Following inhalation of mycelial fragments and spores into the lungs, Blastomyces spp convert into pathogenic yeast and evade host immune defenses to cause pneumonia and disseminated disease. The clinical spectrum of pulmonary blastomycosis is diverse. The diagnosis of blastomycosis requires a high degree of clinical suspicion and involves culture-based and non-culture-based fungal diagnostic tests. The site and severity of infection, and the presence of underlying immunosuppression or pregnancy, influence the selection of antifungal therapy.