Mucormycosis: A comparative update between conventional and molecular diagnosis strategies

Abstract

Mucormycosis is an opportunistic, aggressive, and angioinvasive fungal infection associated with a high mortality rate as it disseminates and infects the whole body if not treated early. Most conventional diagnostic methods require time and may also generate false-negative reports due to the several lacunae associated. On the other hand, molecular methods are rapid, reliable, and can be applied to different biological samples, such as fresh tissue, formalin-fixed paraffin-embedded blocks, serum, and urine. Mucorales are angio-invasive, and many studies have found the circulating fungal DNA (a non-invasive form of DNA) in the blood and urine of the patient. In addition, with the increase in the usage of steroid drugs in this COVID scenario, the rate of mucormycosis infection has taken a sudden rise. In light of this situation, there is an imperative need to diagnose these infections at the earliest.
 Studies on the diagnosis of mucormycosis were explored and retrieved from Pubmed and Google Scholar. Histopathology and culture reports of patients diagnosed with mucormycosis in 2019-2020 were searched and retrieved from the hospital database (ethically permitted) to find the rate of concordance between the techniques. In this review study, different tested molecular techniques are encapsulated, and various primers are documented that are used to identify and classify different Mucoromycota fungi.
 An attempt has been made to compare the feasibility, accuracy adaptability, and time frame used among molecular and conventional methods for the diagnosis of mucormycosis.

A rare case of pediatric gastrointestinal mucormycosis with a review of the literature

“…Early diagnosis of mucormycosis is difficult given its relatively nonspecific initial symptoms [4] , [5] ; the diagnostic dilemma is compounded by inconsistent staining patterns of Mucormycetes on commonly used fungal stains and the challenges and slow timeline of culturing mucormycosis in the routine lab setting [13] , [18] . If mucormycosis is on the differential diagnosis, nucleic acid based diagnostic modalities offer high sensitivity and specificity with a much faster turn-around time: results can be available within hours of sample collection [18] , [19] . A wide array of samples are suitable for testing, including fresh and frozen tissue, formalin-fixed paraffin-embedded tissue, blood, urine, and bronchoalveolar lavage fluid [18] , [20] .…”

“…If mucormycosis is on the differential diagnosis, nucleic acid based diagnostic modalities offer high sensitivity and specificity with a much faster turn-around time: results can be available within hours of sample collection [18] , [19] . A wide array of samples are suitable for testing, including fresh and frozen tissue, formalin-fixed paraffin-embedded tissue, blood, urine, and bronchoalveolar lavage fluid [18] , [20] .…”

A Systematic Review of the Therapeutic Outcome of Mucormycosis

“…Molecular identification of cultured Mucorales species is convenient and remains the gold standard [ 6 ]. Matrix-assisted laser desorption ionization–time of flight mass spectrometry (MALDI- TOF-MS) provides protein fingerprints of fungi, and this method allows rapid and less complicated identification [ 20–22 ].…”

Risk Factors, Clinical Manifestations, and Outcomes of COVID-19-Associated Mucormycosis and Other Opportunistic Fungal Infections

“…The official figure for the total number of COVID-19-associated mucormycosis (CAM) cases in India was 51,775 till November 2021 [ 2 ]. Mucormycosis, colloquially known by the name ‘black fungus’ in Indian media and on social media platforms during COVID-19, was reported in the majority of cases, but many other non-Mucorales opportunistic fungi were also isolated [ 3 , 4 ]. Opportunistic fungal infections (or mycoses) mainly affect persons who have compromised immunity secondary to diabetes, malignancy, HIV, or the use of immunosuppressive drugs [ 5 ].…”