Talaromyces marneffei laboratory cross reactivity with Histoplasma and Blastomyces urinary antigen

Diagnosis of Human Endemic Mycoses Caused by Thermally Dimorphic Fungi: From Classical to Molecular Methods

Human endemic mycoses are potentially fatal diseases caused by a diverse group of fungi that can alter their morphology in response to an increase in temperature. These thermally dimorphic fungi affect both healthy and immunocompromised hosts, causing a substantial health and economic burden. Despite this, the diagnosis of endemic mycoses is still a formidable challenge for several reasons, including similar symptomatology, limited utility of classical diagnostic methods, inaccessibility to reliable molecular approaches in most endemic areas, and a lack of clinical suspicion out of these regions. This review summarizes essential knowledge on thermally dimorphic fungi and the life-threatening diseases they cause. The principle, advantages and limitations of the methods traditionally used for their diagnosis are also described, along with the application status and future directions for the development of alternative diagnostic strategies, which could help to reduce the disease burden in endemic areas.

Immunologic Diagnosis of Endemic Mycoses

The endemic mycoses blastomycosis, coccidioidomycosis, histoplasmosis, paracoccidioidomycosis, cryptococcosis, sporotrichosis, talaromycosis, adiaspiromycosis, and emergomycosis are mostly caused by geographically limited thermally dimorphic fungi (except for cryptococcosis), and their diagnoses can be challenging. Usual laboratory methods involved in endemic mycoses diagnosis include microscopic examination and culture of biological samples; however, serologic, histopathologic, and molecular techniques have been implemented in the last few years for the diagnosis of these mycoses since the recovery and identification of their etiologic agents is time-consuming and lacks in sensitivity. In this review, we focus on the immunologic diagnostic methods related to antibody and antigen detection since their evidence is presumptive diagnosis, and in some mycoses, such as cryptococcosis, it is definitive diagnosis.

Talaromyces stipitatus, a novel agent causing superficial mycosis in a diabetic patient from North India

Among millions of reported fungal species, only a few hundred species are capable of causing diseases in humans and animals that range from superficial to life-threatening infections. Both immunocompetent as well as immunocompromised patients with underlying diseases, such as AIDS, diabetes, etc., are at higher risk of acquiring fungal infections. Superficial mycoses invade the stratum corneum and the outermost layers of the skin. The aim of the present study was to study clinical symptoms, isolate and identify the causal agent in the investigated patient along with sharing insights achieved through reviewing the literature. Direct microscopy, cultural, microscopic, and molecular characterization was done to identify the recovered causal agent. Herein, we report a case of superficial mycosis that affected the left foot of a 65-year-old diabetic male who was a farmer by occupation from district Jammu, Jammu and Kashmir, India. The pathogenic fungal species was identified as Talaromyces stipitatus. To the best of our knowledge, there are no reports on T. stipitatus as a causal agent of skin infection so far. Thus, the causal agent described in the research communication constitutes a new addition to the list of pathogenic non-dermatophytes associated superficially with human skin. In-vitro antifungal activity revealed fluconazole as the most effective antifungal agent against the causal agent.

Recognition of Diagnostic Gaps for Laboratory Diagnosis of Fungal Diseases: Expert Opinion from the Fungal Diagnostics Laboratories Consortium (FDLC)

Fungal infections are a rising threat to our immunocompromised patient population, as well as other nonimmunocompromised patients with various medical conditions. However, little progress has been made in the past decade to improve fungal diagnostics. To jointly address this diagnostic challenge, the Fungal Diagnostics Laboratory Consortium (FDLC) was recently created. The FDLC consists of 26 laboratories from the United States and Canada that routinely provide fungal diagnostic services for patient care. A survey of fungal diagnostic capacity among the 26 members of the FDLC was recently completed, identifying the following diagnostic gaps: lack of molecular detection of mucormycosis; lack of an optimal diagnostic algorithm incorporating fungal biomarkers and molecular tools for early and accurate diagnosis of Pneumocystis pneumonia, aspergillosis, candidemia, and endemic mycoses; lack of a standardized molecular approach to identify fungal pathogens directly in formalin-fixed paraffin-embedded tissues; lack of robust databases to enhance mold identification with matrix-assisted laser desorption/ionization time-of-flight mass spectrometry; suboptimal diagnostic approaches for mold blood cultures, tissue culture processing for Mucorales, and fungal respiratory cultures for cystic fibrosis patients; inadequate capacity for fungal point-of-care testing to detect and identify new, emerging or underrecognized, rare, or uncommon fungal pathogens; and performance of antifungal susceptibility testing. In this commentary, the FDLC delineates the most pressing unmet diagnostic needs and provides expert opinion on how to fulfill them. Most importantly, the FDLC provides a robust laboratory network to tackle these diagnostic gaps and ultimately to improve and enhance the clinical laboratory's capability to rapidly and accurately diagnose fungal infections.

Unusual presentation of pulmonary blastomycosis complicated by amphotericin-induced refractory electrolyte abnormalities

Blastomyces dermatitidis is an endemic mold infection commonly seen in the midwestern of the USA and rarely affects pregnant women. The most common presentation is a pulmonary infection with variable degrees of severity. Of note, the clinical and radiographic findings of pulmonary blastomycosis can be mistaken for other pulmonary pathologies, thus earning the title of ‘the great pretender’. The treatment of choice of infected pregnant patients is amphotericin B, which is known to produce electrolyte imbalances. However, it infrequently causes severe, prolonged and profound hypokalemia and hypomagnesemia. We present the case of a 27-year-old pregnant patient with pulmonary blastomycosis presenting with a lung mass suspicious of malignancy and treated with amphotericin B with subsequent prolonged refractory hypokalemia and hypomagnesemia.

Keywords

pulmonary blastomycosis

pregnancy

biopsy

computed tomography angiography

liposomal amphotericin B