Current Medical Mycology
Volume:9 Issue: 3, Sep 2023

The current study aimed to report a multiplex polymerase chain reaction (PCR) assay as a monitoring technique to differentiate aflatoxigenic from non-aflatoxigenic strains of Aspergillus flavus isolated from pistachio orchards soil.

In total, 25 A. flavus strains were isolated from soil samples of pistachio orchards. To test the strains for Aflatoxin B1(AFB1)-producing ability, thin-layer chromatography (TLC) was used and the amounts of AFB1 were measured by high performance liquid chromatography (HPLC). Multiplex PCR was used as a genome-based method to detect genes responsible for AFB1 production by A. flavus and the results were analyzed in terms of speed and specificity of detection. A set of four primers was designed specifically for the omtA, omtB, ver-1, and aflR genes which are commonly present in aflatoxin biosynthetic pathways.

The AFB1 production by the A. flavus strains ranged from 0 to 321 ρg/μl. Four band patterns of the primer sets were observed only in AFB1-producing A. flavus strains. Moreover, 18 out of the 25 strains showed all four bands belonging to omtA, omtB, ver-1, and aflR, whereas 7 strains did not display omtA, or aflR-related bands, in non-toxigenic and low toxin-producing A. flavus.

The multiplex PCR is a supplementary strategy to current conventional mycotoxin analytical techniques, such as TLC and HPLC. It could be used as an efficient method to differentiate aflatoxigenic from non-aflatoxigenic strains of A. flavus. This achievement is crucial to minimize fungal contamination of food, feed, and agricultural commodities, thereby reducing the risk of subsequent aflatoxin consumption.

Onychomycosis due to dematiaceous fungi is rarely reported and the identification is also quite tricky due to poor sporulation.The recent emergence of dematiaceous fungi as a cause major of onychomycosis is a matter of concern in the field of mycology.  Therefore, this study aimed to understand the dematiaceous fungi as a possible cause of onychomycosis, especially among agricultural workers. In addition, the evaluation of the antifungal susceptibility patterns gave an idea of the accurate drug that will help in the treatment challenge and prevent antifungal resistance. 

The standard procedure was followed for direct microscopic examination and isolating fungi. Furthermore, antifungal susceptibility testing (AFST) was conducted in accordance with the Clinical and Laboratory Standards Institute (CLSI) M-38-A2 protocol.

Both KOH and fungal positivity were recovered in 275 workers out of 356 suspected cases, of which 52% were NDMs, 4.3% were yeast, 28.7% were dermatophytes and 14.9% were sterile hyphae. Among NDMs (52%, n=143), 45.5% (n=65) were hyaline hyphomycetes and 54.5% (n=78) were dematiaceous hyphomycetes. Among dematiaceous fungi, Pestalotiopsis spp., Arthrinium spp., etc. were commonly isolated. Additionally, azoles, amphotericin-B and anidulafungin showed excellent antifungal activity against tested isolates. 

Dematiaceous fungi are now becoming a potential cause of onychomycosis. A more detailed study is needed on the identification of these emerging isolates and the mode of action of antifungal drugs for a better treatment strategy.

Invasive fungal disease (IFD) is a common and serious consequence of leukemia in children and the incidence of these infections has increased due to chemotherapy. This study aimed to present the epidemiology of IFD in a cohort of children with leukemia from a tertiary reference institution in Oman.

A retrospective study of IFDs in pediatric patients below 13 years of age with newly diagnosed or relapsed leukemia was conducted at the Royal Hospital in Muscat, Oman. From 2010 to 2017, IFD episodes in children with leukemia were evaluated retrospectively, considering age, gender, type of leukemia, chemotherapy regimen, IFD detection phase, neutropenia, prevention, diagnostic method, and treatment.

Between 2010 and 2017, 198 children with leukemia were admitted and treated at Royal Hospital. Invasive fungal infection (IFI) was diagnosed in 32 patients out of 198 (16.1%), and IFI was defined as probable and proven in 53% (n=17) and 47% (n=15) of the cases, respectively. At 1.1:1, the male-to-female ratio was roughly equal. According to chest computed tomography scans, 65.6% of patients had radiological features of fungal infections. Positive fungal cultures were found in the bronchoalveolar lavage of three patients, 37.5% of whom had positive blood cultures, and 3% had positive urine cultures as a neonatal invasive candidiasis. In three patients, invasive aspergillosis caused pulmonary IFD, accounting for 9.3% of all infection sites. Candidaemia was found in 28% of IFD patients, and the most common organism was Candida tropicalis (15.6%), followed by Candida prapsilosis (6.25%). Furthermore, the major risk factor was febrile neutropenia.

In children with leukemia, invasive fungal infection is common and serious. Despite aggressive treatment, mortality among these high-risk patients remains high.

Candida auris is a multidrug-resistant yeast that rapidly spreads, making it the leading Candidate for the next pandemic. One main leading cause of emerging resistant C. auris isolates is nonsynonymous mutations. This study aimed to detect the Y132F mutation, one of the most important azole resistance-associated mutations in the ERG-11 gene of C. auris, by developing a reliable high-resolution melt (HRM)-based method.

Five C. auris isolates from Iran, plus three control isolates from other Clades were used in the study. The antifungal susceptibility testing through micro broth dilution was performed to recheck their susceptibility to three azole antifungals,including fluconazole, itraconazole, and voriconazole. Moreover, the polymerase chain reaction (PCR) sequencing of the ERG-11 gene was performed. Following the bioinformatic analysis and HRM-specific primer design, an HRM-based assay was developed and evaluated to detect ERG-11 mutations.

The minimum inhibitory concentrations of fluconazole among Iranian C. auris isolates ranged from 8 to 64 μg/mL. The PCR-sequencing of the ERG-11 gene and bioinformatic analyses revealed the mutation of Y132F, a substitution consequence of A to T on codon 395 in one fluconazole-resistant isolate (IFRC4050). The developed HRM assay successfully differentiated the targeted single nucleotide polymorphism between mutant and wild types (Melting temperature [Tm]: 81.79 ℃ - cycle threshold [CT]: 20.06 for suspected isolate). For both mutant and non-mutant isolates, the mean Tm range was 81.79-82.39 °C and the mean CT value was 20.06-22.93. These results were completely in accordance with the findings of DNA sequencing.

The fast-track HRM-based method successfully detected one of the most common mechanisms of resistance in the ERG-11 gene of C. auris within 3 h. Finally, the development of more panels of HRM assays for the detection of all azole resistance mutations in C. auris ERG-11 is recommended to expand the scope of the field and facilitate the elaboration of rapid and accurate methods of antifungal resistance assessment.

India witnessed an explosive rise in mucormycosis following COVID-19 infection. While rhino orbital mucormycosis was the most common presentation, pulmonary mucormycosis was closely followed. The need for advanced resources and lack of clinical suspicion for COVID-19-associated pulmonary mucormycosis led to widespread underdiagnosis and poor response to late therapy. The study aimed to assess the prevalence of pulmonary mucormycosis in COVID-19-associated rhino-orbital mucormycosis using non-invasive techniques like sputum microscopy and chest imaging. 

A prospective observational study was conducted at the Institute of Internal Medicine, Rajiv Gandhi Government General Hospital between June 2021 and July 2021. All hospitalised patients with proven rhino orbital mucormycosis with or without cerebral involvement within three months of confirmed COVID-19 infection having clinical symptoms compatible with pulmonary mucormycosis were included in the study. These patients were screened for probable and possible COVID-19-associated pulmonary mucormycosis using CT chest imaging and sputum microscopy within 48 hours of hospital admission.

Out of 50 patients with rhino-orbital mucormycosis, 16% had associated possible or probable pulmonary mucormycosis. All 8 patients were diabetics and had characteristic CT chest findings while only half had positive sputum microscopy. A higher prevalence of disseminated COVID-19-associated mucormycosis was noted among 51-60 years males with the use of corticosteroids and oxygen for COVID-19 therapy. The mortality was 100% in probably disseminated mucormycosis, 50% in possible disseminated mucormycosis and only 9.5% in isolated rhino-orbital mucormycosis. 

Hence, non-invasive and feasible methods such as sputum microscopy and chest imaging can be considered for early screening and intensive management of probably disseminated mucormycosis to improve prognosis.

Regarding the wide-spectrum antimicrobial effects of curcumin and silver, this study aimed to evaluate the antifungal activity of green-synthesized curcumin-coated silver nanoparticles (Cur-Ag NPs) against a set of Candida and Aspergillus species.

Cur-Ag NPs were synthesized by mixing 200 µL of curcumin solution (40 mM) and 15 mL of deionized water. The mixture was stirred for 3-5 min, followed by the addition of 2.5 mL of silver nitrate solution (2.5 mM). The resulting solution was incubated for 3 days. Antifungal susceptibility of 30 fungal isolates of Aspergillus and Candida to fluconazole and itraconazole, as well as the activity of Cur-Ag NPs against the isolates, were determined, both alone and in combination, using broth microdilution according to the Clinical and Laboratory Standards Institute guidelines.

Cur-Ag NPs demonstrated promising antifungal activity, particularly against Candida species. The geometric mean value of the minimum inhibitory concentration of Cur-Ag NPs was significantly lower than that of fluconazole for all the studied fungi. Similarly, it was lower than those of itraconazole in C. albicans and A. fumigatus. The minimum fungicidal concentrations of Cur-Ag NPs were markedly better than those of fluconazole but still inferior to those of itraconazole.

Cur-Ag NPs demonstrated indisputable antifungal activity and great potential that can be harnessed to combat fungal infections, particularly those caused by azole-resistant strains of Aspergillus and Candida.

Invasive fungal infections caused by Cyberlindnera fabianii have recently increased despite its low virulence potential. Limited information in widely used commercial biochemical identification systems, leads to underestimation of Cy. fabianii infections in the clinical setting.

Case report: 

We report a case of prosthetic joint infection in a patient who had a previous history of total knee replacement surgery. Cy. fabianii was recovered from intraoperative culture specimens identified by Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry and confirmed using molecular assays. It was initially misidentified as Candida utilis by phenotypic identification.

Due to the emergence of uncommon yeast species, it is important to accurately identify and perform antifungal susceptibility testing for uncommon yeast isolates for appropriate management.

The COVID-19 pandemic may be an aggravating risk factor for the delay of the diagnoses of serious illnesses, such as oral squamous cell carcinoma, as well as poor management of patients with underlying morbidities, the onset of oral lesions, and antifungal susceptibility to opportunistic fungal infections. Oral candidiasis is one of the most common oral features of COVID-19.

Case Report: 

This study aimed to report an 83-year-old female diagnosed with oral carcinoma who developed oropharyngeal candidiasis after falling ill with COVID-19. In late 2020, this patient was hospitalized for COVID-19 pneumonia. A fissured tongue with white scars appeared after the COVID-19 recovery that caused pain, dysphasia, and dysarthria. The sequencing result based on the internal transcribed spacer rDNA region confirmed Candida glabrata. Its antifungal susceptibility showed susceptibility to nystatin, fluconazole, and caspofungin, but resistance to the other azoles and amphotericin B.

Risk of fungal infections, such as Candida seems to be high in patients with severe COVID-19, mainly affecting the oral mucosa. However, whether they are directly attributed to COVID-19 or other surrounding factors is unknown.