Utility of an in-house real-time PCR in whole blood samples as a minimally invasive method for early and accurate diagnosis of invasive mould infections.

INTRODUCTION: Invasive mould infections (IMIs) are a leading cause of death in patients with compromised immune systems. Proven invasive mould infection requires detection of a fungus by histopathological analysis of a biopsied specimen, sterile culture, or fungal DNA amplification by PCR in tissue. However, the clinical performance of a PCR assay on blood samples taken from patients suspected of invasive mould disease has not been fully evaluated, particularly for the differential diagnosis of invasive aspergillosis (IA) and invasive Mucormycosis (IM). OBJECTIVES: To assess the diagnostic utility of our previously validated in-house real-time PCR in blood samples for diagnosis of invasive aspergillosis and mucormycosis in patients with suspected invasive mould infection. METHODS: All patients with suspected invasive mould infection were prospectively enrolled from May 2021 to July 2021. Conventional fungal diagnosis was performed using tissue and respiratory samples. In-house PCR was performed on blood samples and its diagnostic performance evaluated. RESULTS: A total of 158 cases of suspected invasive mould infection were enrolled in the study. The sensitivity and specificity of in-house PCR performed on blood samples was found to be 92.5% and 81.4% respectively for diagnosis of probable IA, and 65% and 84.62% respectively for diagnosis of proven and probable IM. It was also able to detect 3 out of 5 cases of possible IM where no other microbiological evidence of IM was obtained. CONCLUSIONS: This assay could be helpful in minimally invasive diagnosis of IMIs for patients in whom invasive sampling is not feasible, especially as a preliminary or screening test. It can help in early diagnosis, anticipating conventional laboratory confirmation by days or weeks. Possible correlation between fungal load and mortality can help in initiating aggressive treatment for patients with high initial fungal load.

Utility of in-house and commercial PCR assay in diagnosis of Covid-19 associated mucormycoss in an emergency setting in a tertiary care center.

Introduction. Invasive mucormycosis (IM) is a potentially fatal infection caused by fungi of the order Mucorales. Histopathology, culture, and radiology are the mainstays of diagnosis, but they are not sufficiently sensitive, resulting in delayed diagnosis and intervention. Recent studies have shown that PCR-based techniques can be a promising way to diagnose IM.Hypothesis/Gap Statement. Early diagnosis of fungal infections using molecular diagnostic techniques can improve patient outcomes, especially in invasive mucormycosis.Aim. The aim of this study was to evaluate the utility of our in-house mould-specific real time PCR assay (qPCR) in comparison with the commercially available real time PCR (MucorGenius PCR), for the early diagnosis of mucormycosis in tissue samples from patients with suspicion of invasive mucormycosis (IM). This in-house assay can detect and distinguish three clinically relevant mould species, e.g. Aspergillus spp., Mucorales and Fusarium spp. in a single reaction with only one pair of primers, without the need for sequencing.Methodology. We enrolled 313 tissue samples from 193 patients with suspected IM in this prospective study. All cases were classified using EORTC/MSGERC guidelines. All samples were tested using traditional methods, in-house qPCR, and MucorGenius PCR.Results. Using direct microscopy as a gold standard, the overall sensitivity and specificity of in-house qPCR for detection of IM was 92.46% and 80% respectively, while that of the MucorGenius PCR was 66.67% and 90% respectively. However, co-infection of IM and IA adversely affected the performance of MucorGenius PCR in detection of IM.The in-house PCR detected Aspergillus spp. in 14 cases and Fusarium spp. in 4 cases which showed clinical and radiological features of fungal sinusitis. The in-house qPCR also performed better in detecting possible cases of IM. This aids early diagnosis and appropriate treatment to improve patient outcomes.Conclusion. Because the in-house PCR is not only sensitive and specific, but also entirely based on SYBR Green for detection of targets, it is less expensive than probe-based assays and can be used on a regular basis for the diagnosis of IM in resource-constrained settings. It can be used to distinguish between mucormycosis and fungal sinusitis caused by Aspergillus and Fusarium in high-risk patients, as well as to accurately detect Mucorales in fungal co-infection cases.

Lodderomyces elongisporus fungemia in a patient with previous cardiac surgery: Case report and review of literature.

Lodderomyces elongisporus is a rare cause of invasive fungal infections. Most phenotypic tests that are routinely used for identification of yeasts fail to identify this organism. However, chromogenic media for yeasts, MALDI-TOF MS and DNA sequencing can be used for correct identification. We report a case of fungemia complicated by infective endocarditis and intracerebral bleeding in a pediatric patient with previous cardiac surgery.

A study on candiduria in neonates and infants from a tertiary care center, North India.

PURPOSE: Candida albicans is the major cause of fungal UTI in neonates and infants but nowadays non albicans Candida is also increasing and these are mostly multidrug resistant. So it's important to know the species of candidal UTI for the proper management. This study was undertaken to determine the Candida species distribution in UTI along with their susceptibility pattern and outcome in infants and neonates admitted in different wards and ICU of our hospital. We also assess the incidence rate of candiduria in ICUs. METHOD: Urine samples were collected from infants and neonates presented in pediatrics and neonatal ICU (intensive care units) and clinical wards with a clinical suspicion of candiduria and infants at risk of invasive candidiasis were also included in the study. Identification of Candida sp. was done by Gram's staining, germ tube test, chlamydospore formation on corn meal agar, color appearance on CHROM agar and also confirmed by MALDI-TOF Assay. Antifungal susceptibility was performed by using broth microdilution method as per the CLSI M27-A3/M27-S4. RESULT: Urine samples were received from 219 infants, and Candida was isolated from samples from 52 infants (isolation rate 23.75%), of which 30 were admitted in pediatric or neonatal ICU and 22 in the wards. The incidence rate of candiduria in ICU was 3.25%. Candida albicans was the most frequently isolated species from the samples of infants in the wards (13/22 i.e. 59%), while Candida tropicalis was most frequently isolated from samples of infants in the ICUs (13/30 i.e. 43.34%). Candida glabrata was the least commonly isolated species and was only encopuntered in the ICU. There was no discrepancy between the results of conventional methods of identification and MALDI-TOF. Antifungal susceptibility was performed for 18 randomly selected isolates. All were found to be susceptible to caspofungin, micafungin, itraconazole, voriconazole, fluconazole, amphotericin B. CONCLUSION: High suspicion of candiduria is needed especially in ICU admitted infants and identification of candida at species level along with the susceptibility pattern is important for the better management of patients.

Capsule-Deficient Cryptococcal Meningitis: A Diagnostic Conundrum.

Cryptococcosis is a serious systemic mycosis. Its incidence has escalated in the past four decades. Cryptococcus neoformans causes localized or disseminated infection in immunocompromised and immunocompetent patients. The capsulated form is commonly encountered which can be diagnosed on an India ink preparation or antigen detection. However, the noncapsulated forms are very rare and require a high index of suspicion for correct diagnosis. Herein, we present a case of cryptococcal meningitis due to a noncapsulated strain in an apparently immunocompetent patient with no proven immunodeficiencies along with review of world literature. Such cases are a diagnostic challenge for the clinician as well as microbiologist.