Annals of Clinical Microbiology, The official Journal of the Korean Society of Clinical Microbiology
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Young Bok Lee, Mingyu Kim, Dong Soo Yu
Ann Clin Microbiol 2025 March, 28(1):1. Published on 30 December 2024.
(This article belongs to the Special Issue on Current Epidemiology and Laboratory Diagnosis of Fungal Infections in Korea.)
Cutaneous dermatophyte infections, dermatophytosis, are common worldwide, affecting various age groups and body parts. Despite advancements in antifungal therapies, the prevalence of dermatophytosis continues to increase, posing significant challenges for diagnosis and treatment. This review provides an overview of the prevalence, clinical features, and diagnostic methods for dermatophytosis in Korea. A comprehensive review of domestic reports and research on dermatophytosis in Korea was conducted using data from KoreaMed. This study covers the various clinical presentations, age distributions, seasonal trends, and types of dermatophytes identified in different body areas. Dermatophytosis in Korea have shown changing patterns in terms of prevalence and causative species. Trichophyton rubrum remains the most common causative organism, with varying presentations depending on the site of infection, such as tinea pedis, tinea corporis, tinea capitis, tinea faciei, and onychomycosis. Diagnostic practices largely depend on the potassium hydroxide smear test, which has limited sensitivity, particularly for onychomycosis. Recent trends indicate an increase in the incidence of dermatophytosis among older adults, which may be linked to underlying health conditions and lifestyle changes. Dermatophytosis in Korea exhibit diverse clinical manifestations influenced by factors such as patient age, body site, and seasonal variation. Improved diagnostic methods are needed to enhance the accuracy and guide appropriate treatment, especially with the emergence of antifungal-resistant strains. This review aims to provide a better understanding of the current state of dermatophytosis in Korea and contribute to more effective management and prevention strategies.
Eun Ha Lee, Chi Rac Hong
Ann Clin Microbiol 2025 March, 28(1):2. Published on 30 December 2024.
(This article belongs to the Special Issue on Current Epidemiology and Laboratory Diagnosis of Fungal Infections in Korea.)
Purpose: The human gut mycobiome comprises diverse fungal species and plays a crucial role in health and disease, despite its relatively low abundance compared to bacterial populations. This review provides an overview of the mycobiome’s composition, developmental patterns, and dysbiosis in various pathological conditions. As well, the complex interactions of fungal communities within the gut microbiome are discussed.
Current content: The development of the gut mycobiome follows patterns similar to those of the bacterial microbiome, with birth mode, diet, and age being key determinants. In contrast to the bacterial trends, mycobiome diversity increases during childhood and old age. Recent studies have revealed variations in the mycobiome composition across different ethnic groups. Mycobiome dysbiosis is associated with autoimmune, gastrointestinal, and cardiovascular diseases. Certain fungi, notably Candida albicans, are relatively more abundant in pathological states. Fungal metabolic activity, particularly secondary metabolite production, can significantly affect disease progression. Bacterial–fungal interactions in the gut microbiome are complex and modulated by environmental factors, such as diet and antibiotic use. Moreover, the gut mycobiome modulates therapeutic efficacy. Gut fungi enhance the bioactivity of compounds derived from natural products through biotransformation, including their anticancer and anti-inflammatory effects. This suggests the potential of the gut mycobiome to optimize the therapeutic efficacy of natural products.
Conclusion: This review highlights the relevance of the gut mycobiome as both a diagnostic biomarker and a therapeutic target. Future research should focus on elucidating the causal relationships between mycobiome alterations and disease states, and further explore bacterial–fungal interactions within the gut ecosystem.
Jayoung Kim
Ann Clin Microbiol 2024 December, 27(4):217-219. Published on 20 December 2024.
(This article belongs to the Special Issue on Current Epidemiology and Laboratory Diagnosis of Fungal Infections in Korea.)
Jayoung Kim
Ann Clin Microbiol 2024 December, 27(4):221-230. Published on 20 December 2024.
(This article belongs to the Special Issue on Current Epidemiology and Laboratory Diagnosis of Fungal Infections in Korea.)
Taxonomy includes classification, nomenclature, and identification. Identification assigns unknown fungi to species based on their strain characteristics. Traditionally, fungal taxonomy relied on morphological, physiological, and biochemical traits. However, advancements in molecular phylogeny, especially multilocus sequence analysis (MLSA), have revolutionized fungal taxonomy. MLSA combines phylogenetic and genetic approaches. Although effective, MLSA may not fully reflect biodiversity or distinguish between closely related species. Polyphasic taxonomy integrates genotypic, phylogenetic, chemotaxonomic, and phenotypic data into a consensus classification system. Polyphasic taxonomy was first applied to Rhodotorula glutinis in 2001 and is now widely accepted. Phenotypic traits, such as protein profiles and chemotaxonomic markers, analyzed using techniques such as matrix-assisted laser desorption ionization-time of flight mass spectrometry, are effective for yeast and filamentous fungi. Genotypic data from DNA/RNA sequencing, compared with data from databases such as Index Fungorum and MycoBank, aids species identification and synonym verification. Despite its practicality, the polyphasic approach lacks strict guidelines, resulting in varied interpretations.
Yong Jun Kwon, Jong Hee Shin
Ann Clin Microbiol 2024 December, 27(4):231-244. Published on 20 December 2024.
(This article belongs to the Special Issue on Current Epidemiology and Laboratory Diagnosis of Fungal Infections in Korea.)
Purpose: Candidemia is a common cause of nosocomial bloodstream infections associated with high mortality rates. Its incidence varies significantly across countries and hospitals, and its epidemiology is a subject of continuous investigation. This review aims to provide a comprehensive analysis of candidemia in Korea, addressing its changing epidemiology, species distribution, antifungal resistance, and clinical implications.
Current content: In Korea, Candida albicans remains the most common isolate in blood cultures; however, infections caused by non-albicans Candida species are increasing. The 30day mortality rates for patients with candidemia vary considerably across different Candida species, with Candida tropicalis at 47.0%, C. albicans at 36.4%, Candida glabrata at 34.7%, and Candida parapsilosis at 22.5%. Recent Korean studies have highlighted the clonal spread of bloodstream infections caused by C. parapsilosis with the Erg11p Y132F mutation, and certain isolates are becoming endemic to specific healthcare settings. C. glabrata poses a significant threat; this species is increasingly resistant to antifungal medications and multidrug-resistant isolates are emerging. Whole-genome sequencing analysis elucidates the transmission dynamics of clonal bloodstream isolates of C. glabrata among patients receiving antifungal therapy. This analysis demonstrates varying degrees of fluconazole susceptibility and distinct Pdr1p mutation profiles, identifying the molecular mechanisms underlying multidrug resistance. Furthermore, the first nosocomial outbreak of Candida auris underscores the importance of multicenter surveillance for identifying and managing C. auris outbreaks.
Conclusion: The changing epidemiology of candidemia, along with the continued emergence of antifungal resistance among bloodstream isolates of non-albicans Candida species warrants continuous monitoring of candidemia in Korea. By integrating clinical, microbiological, and public health perspectives, healthcare systems can develop robust strategies to optimize therapeutic approaches, prevent nosocomial transmission, and ultimately reduce morbidity and mortality associated with these life-threatening infections.
Eun Jeong Won
Ann Clin Microbiol 2024 December, 27(4):245-255. Published on 16 December 2024.
(This article belongs to the Special Issue on Current Epidemiology and Laboratory Diagnosis of Fungal Infections in Korea.)
Candidemia is the most common healthcare-associated invasive fungal infection with high crude mortality rates. It primarily affects critically ill or severely immunocompromised patients, complicating early diagnosis and prompting the initiation of appropriate antifungal therapy. The gold standard for diagnosing candidemia is blood culture; however, the sensitivity of this test is low and requires at least two days for species identification. These limitations have led to the development of alternative diagnostic methods that are more sensitive and have shorter turnaround times. Here, we review the currently available methods for the nonculturebased diagnosis of candidemia, including (i) immunological diagnostics targeting Candida-related antigens, (ii) human antibodies to Candida-related antigens, and (iii) molecular diagnostics. The strengths, uses, and limitations of each methodology are discussed. Immunological diagnostics targeting Candida-related antigens and human antibodies to these antigens provide supportive evidence for diagnosing candidemia. Advances in molecular diagnostics have shown promising results in facilitating early candidemia diagnosis, potentially improving patient outcomes.
Myeong Hee Kim
Ann Clin Microbiol 2024 December, 27(4):257-265. Published on 20 December 2024.
(This article belongs to the Special Issue on Current Epidemiology and Laboratory Diagnosis of Fungal Infections in Korea.)
Cryptococcosis is a major invasive fungal infection affecting both immunocompromised and immunocompetent hosts worldwide and is mainly caused by Cryptococcus neoformans and Cryptococcus gattii. C. neoformans accounts for 90% of all infections and primarily causes central nervous system infections. Although C. gattii is primarily found in tropical and subtropical regions, infections have recently been reported in temperate areas such as Korea. Genetic studies in Korea indicated that most C. neoformans strains are of the VNIST5 type and show genetic homogeneity. In contrast, genetic studies on C. gattii are limited. Cryptococcosis is diagnosed using microscopy, serological tests, culture, and molecular tests. Although it can be detected in the cerebrospinal fluid or body fluids using the India ink method, confirmation through culture is essential for a definitive diagnosis. Cryptococcal antigen testing is economical, highly sensitive, and specific; therefore, it is widely used for the diagnosis of cryptococcosis. Molecular methods have recently been introduced; however, their applications remain limited. The recommended treatment for cryptococcal infections includes amphotericin B alone or in combination with flucytosine or fluconazole. Secondary resistance to flucytosine and fluconazole is common. The Clinical and Laboratory Standards Institute and European Committee on Antimicrobial Susceptibility Testing recommend the broth microdilution method. Several commercial methods for antifungal susceptibility testing have been developed and are currently in use; however, more data are required to establish breakpoints.
Young Ah Kim
Ann Clin Microbiol 2024 December, 27(4):267-270. Published on 20 December 2024.
Enterobacter species were isolated from the sputum of an 84-year-old female patient with fever, chills, cellulitis in the right elbow, and pyogenic arthritis in the left shoulder. The bacteria were identified using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) and whole-genome sequencing (WGS). This strain was defined as a carbapenem-resistant Enterobacterales (CRE) by the MicroScan NG MIC 44 panel without applying the revised guidelines of the Korea Disease Control and Prevention Agency properly. MALDI-TOF MS is commonly used to determine species, but the accurate identification of Enterobacter subspecies remains challenging. An Etest or disk diffusion test is recommended to confirm ertapenem resistance when an isolate exhibits resistance solely to ertapenem among carbapenems.
Dong Heon Shin, Joon Kim, Wee Gyo Lee
Ann Clin Microbiol 2024 December, 27(4):271-277. Published on 3 December 2024.
Prototheca wickerhamii is an achlorophyllic algae that rarely acts as an opportunistic pathogen in humans. We report the case of a 66-year-old female patient with a history of diabetes mellitus who presented with a pus-like discharge from face, facial redness, and swelling. The patient was admitted to the emergency room with worsening facial pain. Gram staining from pus-like discharge revealed yeast like features; however, an isolated colony on a blood agar plate was not identified using VITEK 2 (Biomerieux) or matrix-assisted laser desorption/ionization time-of flight mass spectrometry (MALDI-TOF) using VITEK®MS (Biomerieux). Lactophenol cotton blue staining of the colony revealed characteristic sporangia and endospore features. After performing the protein extraction procedure for filamentous fungi (mold) isolates using ethanol and formic acid, MALDI-TOF MS identified the colony as Prototheca wickerhamii, with 99.9% confidence. This case indicates that Prototheca spp. require specialized sample preparation steps, such as the ethanol/formic acid extraction procedure, for identification using MALDI-TOF MS.
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