Retrospective clinical and microbiologic analysis of metagenomic next-generation sequencing in the microbiological diagnosis of cutaneous infectious granulomas.

BACKGROUND: Cutaneous infectious granulomas (CIG) are localized and chronic skin infection caused by a variety of pathogens such as protozoans, bacteria, worms, viruses and fungi. The diagnosis of CIG is difficult because microbiological examination shows low sensitivity and the histomorphological findings of CIG caused by different pathogens are commonly difficult to be distinguished. OBJECTIVE: The objective of this study is to explore the application of mNGS in tissue sample testing for CIG cases, and to compare mNGS with traditional microbiological methods by evaluating sensitivity and specificity. METHODS: We conducted a retrospective study at the Department of Dermatology of Sun Yat-sen Memorial Hospital, Sun Yat-sen University from January 1st, 2020, to May 31st, 2024. Specimens from CIG patients with a clinical presentation of cutaneous infection that was supported by histological examination were retrospectively enrolled. Specimens were delivered to be tested for microbiological examinations and mNGS. RESULTS: Our data show that mNGS detected Non-tuberculosis mycobacteria, Mycobacterium tuberculosis, fungi and bacteria in CIG. Compared to culture, mNGS showed a higher positive rate (80.77% vs. 57.7%) with high sensitivity rate (100%) and negative predictive value (100%). In addition, mNGS can detect more pathogens in one sample and can be used to detect variable samples including the samples of paraffin-embedded tissue with shorter detective time. Of the 21 patients who showed clinical improvement within a 30-day follow-up, eighteen had their treatments adjusted, including fifteen who continued treatment based on the results of mNGS. CONCLUSIONS: mNGS could provide a potentially rapid and effective alternative detection method for diagnosis of cutaneous infectious granulomas and mNGS results may affect the clinical prognosis resulting from enabling the patients to initiate timely treatment.

Epidemiology and Clinical Findings of Tinea Capitis: A 23-Year Retrospective, Single-Center Study in Guangzhou, China.

BACKGROUND: Tinea capitis (TC) is one of the most common public health concerns due to its high incidence in preadolescent children. The epidemiological and clinical characteristics of TC vary depending on geographical regions and have changed over the past decades. OBJECTIVES: This study aimed to identify epidemiological changes in recent decades, including the prevalence and clinical and mycological characteristics of TC in southern China. METHODS: We conducted a retrospective study at the Department of Dermatology of Sun Yat-sen Memorial Hospital, Sun Yat-sen University from June 1997 to August 2020. RESULTS: We retrospectively evaluated 401 TC patients. Of these, 157 patients (39.2%) were preschool children aged 3-7 years and the majority were males. However, the prevalence in children under 3 years old is on the rise (from 19.67% during 1997-2010 to 32.49% during 2011-2020). Grey patches were the most common clinical pattern and mostly occurred in children (71.3%), while the proportion of grey patches and black dots was almost the same in adults. Although Microsporum canis (76%) was the most common causative organism, the number of the T. mentagrophytes complex, as a zoophilic fungus, has increased more than that of the anthropophilic fungi T. violaceum in the recent decade. There was a significant difference in the portion of sex among different age groups, and the gender difference was more notable in the adult group, which showed that the TC prevalence in females was 9 times that in males. In males, M. canis and the T. mentagrophytes complex were the two most common causative fungi, while M. canis and T. violaceum were the two most common causative fungi in females. Additionally, approximately 61.7% of black dot TCs occurred in females. For treatment, oral antifungal therapeutics were widely used in most patients with different treatment durations, although without a significant difference in efficacy (P = 0.106). CONCLUSIONS: In the last decade, the prevalence of TC in children under 3 years old increased, and boys dramatically outnumbered girls. In adults, the TC prevalence in females is nine times that in males, and most TCs occurring in females are presented as black dots. Moreover, the zoophilic T. mentagrophytes complex has replaced T. violaceum and is now the second most prevalent organism, followed by M. canis of TC.