Fungal Infections in Intensive Care Unit: Challenges in Diagnosis

Opportunistic fungi have emerged as serious threats particularly among patients of Intensive Care Unit (ICU) over the past few decades. The patients in ICU present special challenges, they are at risk for a variety of complications including the development of new infections. Recent advances in medical technology have not only increased the survival rate of critically ill patients admitted to ICU but at the same time have led to an increase in the number of life-threatening infections due to opportunistic fungi. The most frequently encountered fungal infections are caused by Candida albicans, Cryptococcus neoformans, and Aspergillus fumigatus. There are reports about increase in the prevalence of infections caused by non-albicans Candida spp., non-fumigatus Aspergillus spp., Zygomycetes and hyaline molds (e.g., Fusarium and Scedosporium spp.). This myriad of infection makes diagnosis a challenge for the clinicians. Traditional diagnostic methods, such as histopathology and culture, which are still considered as the gold standards, have low sensitivity and time-consuming. The other alternative to the conventional method, becoming popular is serologic and molecular techniques. Tests like β-glucan test for invasive Candida spp. as well as molds and galactomannan antigen test to identify Aspergillus with a simple blood sample have already been established as important diagnostic tool and are implemented in routine clinical practice. On the other hand, use of PCR-based assays, DNA sequencing and other molecular approaches, such as Matrix-Assisted Laser Desorption Ionization-Time of Flight (MALDI-TOF) mass spectrometry, have shown promising results in clinical trials. However they still need to undergo standardization before they are use to accurately detect fungal pathogens.