Current Medical Mycology最新文献

Background and purpose: This study aimed to assess the effect of Allium cepa ethanolic extract (ACE) loaded polyacrylonitrile (PAN) and polyvinyl pyrrolidone (PVP) nanofibers on Candida albicans (C. albicans) CDR1 and CDR2 genes expression.

Materials and methods: The minimum inhibitory concentrations (MICs) of ACE against C. albicans ATCC 10231 and clinical fluconazole (FLC)-resistant C. albicans PFCC 93-902 were determined using the Clinical and Laboratory Standards Institute (CLSI) protocol (M27-Ed4) at a concentration range of 45.3-5800 µg/ml. The nanofibers containing ACE (60 wt%) were fabricated using the electrospinning technique. The expression of the CDR1 and CDR2 genes was studied in the fungus exposed to ACE-loaded nanofibers and 0.5×MIC concentration of FLC using the real-time polymerase chain reaction.

Results: MIC₅₀ and MIC₉₀ of ACE against FLC-resistant C. albicans were 725 and 1450 μg/mL, respectively. The expression of CDR1 (4.5-fold) and CDR2 (6.3-fold) were down-regulated after the exposure of FLC-resistant C. albicans to ACE-loaded nanofibers (P<0.05). Furthermore, the expression of CDR1 (2.8-fold) and CDR2 (3.2-fold) were up-regulated in FLC-treated C. albicans (P<0.05).

Conclusion: The results revealed that nanofibers containing ACE interact with drug-resistant genes expressed in C. albicans. Further studies are recommended to investigate the mode of action and other biological activities of ACE-loaded nanofibers against C. albicans and other pathogenic fungi.

Background and purpose: Coronavirus disease 2019 (COVID-19) has become a significant clinical challenge in healthcare settings all over the world. Critically ill COVID-19 patients with acute respiratory distress syndrome may be at increased risk of co-infection with pulmonary aspergillosis. This study aimed to describe a clinical case of proven pulmonary aspergillosis caused by Aspergillus tubingensis in a 59-year-old man with a history of hospitalization due to COVID-19 infection.

Case report: The Covid-19 infection was confirmed by positive nasopharyngeal polymerase chain reaction. He had a cavitary lesion measured 20 mm in diameter with intracavitary soft tissue density in the left lung in the first chest computerized tomography scan. After 25 days, he showed two cavitary lesions in both lungs which raised suspicion of fungal infection; hence, the patient underwent a trans-thoracic biopsy of the cavitary lesion. The direct examination and culture of the biopsy material revealed Aspergillus species. To confirm the Aspergillus species identification, the beta-tubulin region was sequenced. The patient was treated with oral voriconazole.

Conclusion: This report underlined the importance of early diagnosis and management of invasive fungal infections in severe COVID-19 patients.

Background and purpose: The predominant cause of candidiasis was Candida albicans which has recently changed to non-Candida albicans Candida (NCAC) (i.e., Candida spp. other than the C. albicans). The NCAC spp., earlier considered non-pathogenic or minimally virulent, are now considered a primary cause of morbidity and mortality in immunocompromised individuals. Given the NCAC spp.has become more common in clinical cases, this study aimed to determine the prevalence of NCAC spp. in different clinical specimens and assess a few of their virulence factors.

Materials and methods: Routine samples for bacterial culture and sensitivity that showed colony characteristics, like Candida on Blood Agar and microscopic features resembling Candida spp., were processed further. Candida isolates underwent tests for chlamydospore formation and biochemical tests, including sugar fermentation and sugar assimilation tests. These were grown at 42oC, and their colony color was identified using HiCrome^TM Candida Differential Agar (HiMedia Laboratories Pvt. Ltd., Mumbai, India), HiCandida ^TM Identification Kit (HiMedia Laboratories Pvt. Ltd., Mumbai, India), and VITEK-2® Compact (Biomérieux, France). Virulence factors, such as adherence to buccal epithelial cells (ABEC), biofilm formation, hemolytic activity, and production of coagulase enzyme were also tested.

Results: Mean age of the patients was 38.46 years with a male-female ratio of 1.36:1. In total, 137 Candida isolates were recovered; 45.3%, 19.7%, and 13.9% of the isolates were isolated from urine, vaginal swabs, and oropharyngeal swabs, respectively. Moreover, 55 (40.1%) isolates were those of C. albicans and 82 (59.9%) isolates belonged to NCAC spp., with C. tropicalis (23.4%) contributing highest among NCAC species. Furthermore, C. albicans (3; 50%) was the most common spp. in cases of candidemia. Haemolysin production (85.5%) and ABEC (78.2%) were the major virulence factors in C. albicans. C. tropicalis (59.4%) and C. dubliniensis (50%) showed maximum ABEC. Biofilm forming capacity was higher in C. tropicalis (78.1%) than C. albicans (67%).

Conclusion: Results of this study suggest varied prevalence and virulence based on geographical locations, even within a subcontinent. It clearly indicates the emergence of the NCAC spp. and their predominance in different body fluids. Identification of Candida to the spp. level should become a routine in all laboratories.

Background and purpose: The most common etiological agents of human dermatophytosis in various parts of the world are Trichophyton rubrum, Trichophyton interdigitale, and Epidermophyton floccosum. The main aim of this study was to design and evaluate a simple and straightforward multiplex polymerase chain reaction (PCR) assay for reliable identification/differentiation of these species in clinical isolates.

Materials and methods: The reliable sequences of several molecular targets of dermatophytes species were used to design a multiplex PCR for the identification of common pathogenic dermatophytes. The isolates and clinical specimens examined in this study included seven standard strains of dermatophytes, 101 isolates of dermatophytes and non-dermatophyte molds/yeasts which had already been identified by sequencing or PCR-restriction fragment length polymorphism (RFLP), and 155 clinical samples from patients suspected of cutaneous mycoses.

Results: Species-specific primer pairs for T. rubrum and T. interdigitale/T. mentagrophytes were designed based on the sequence data of the translation elongation factor 1-alpha gene, and the primers for E. floccosum targeted the specific sequence of the internal transcribed spacer region (ITS). The multiplex PCR successfully detected T. rubrum, T. interdigitale/T. mentagrophytes, and E. floccosum strains that were identified by sequencing or PCR-RFLP. However, the primer pairs selected for T. interdigitale/T. mentagrophytes cross-reacted with Trichophyton tonsurans. In testing the PCR system directly for clinical samples, the proportion of positive multiplex PCR was higher than positive culture (68.1% vs. 55.4%, respectively).

Conclusion: The multiplex assay could detect three common agents out of several causal agents of dermatophytosis, namely T. rubrum, T. interdigitale, and E. floccosum. Therefore, by adding pan-dermatophyte primers it can be used as a comprehensive detection/identification test.