Relationships among genotypes, virulence and clinical forms of Sporothrix schenckii infection

This study explored the relationships among genotypes, virulence and clinical forms of Sporothrix schenckii. Genomic DNA from isolates of S. schenckii, collected from different clinical forms of sporotrichosis, was amplified by randomly amplified polymorphic DNA (RAPD). Suspensions of different isolates of S. schenckii were inoculated into healthy BALB/c mice to compare their virulence, and the numbers and distribution of spores were determined by histological analysis. RAPD analysis indicated that the isolates from different clinical forms of sporotrichosis belonged to different genotypes. The mice inoculated with isolates from disseminated sporotrichosis showed an earlier onset of illness and more severe lesions than those inoculated with isolates from lymphocutaneous sporotrichosis, which, in turn, showed an earlier onset of illness and more severe lesions than those inoculated with isolates from fixed cutaneous sporotrichosis. Healthy BALB/c mice injected with isolates from disseminated sporotrichosis died within 10 days, whereas isolates from lymphocutaneous sporotrichosis and fixed cutaneous sporotrichosis failed to cause death. Histologically, mice inoculated with isolates from disseminated sporotrichosis had more spores than those inoculated with isolates from lymphocutaneous sporotrichosis and fixed cutaneous sporotrichosis. Thus, different genotypes may be associated closely with the virulence of different clinical forms of S. schenckii infection.     

申克孢子丝菌的随机扩增DNA指纹分型

目的：对申克孢子丝菌进行基因分型研究,探索申克孢子丝菌的基因分型标准。方法：用光镜对2株标准株,4株环境分离株和24株临床分离菌株进行形态特征观察,再用随机扩增DNA指纹方法(RAPD)对DNA进行PCR扩增,根据扩增产物的电泳带型来分析DNA多态性。结果：30株菌株镜下可见2种形态结构;30株申克孢子丝菌的DNA指纹带型不同;多引物聚类分析表明,3条引物可将30株不同地区来源申克孢子丝菌分作11个型。结论：(1)在我国申克孢子丝菌中存在2种不同的形态结构。(2)申克孢子丝菌中存在不同的基因型。(3)RAPD法用于申克孢子丝菌菌株鉴定是一种快速、方便、可行的方法。     

Successful treatment of a disseminated Sporothrix schenckii infection and in vitro analysis for antifungal susceptibility testing

We report a case of a diabetic patient with localized osteoarticular sporotrichosis followed by widespread dissemination of the infection, which was successfully treated with amphotericin B. In addition, we evaluated the in vitro antifungal activity of 4 agents against both the mycelial and the yeast forms of the isolated fungus.     

Epidemiological and clinical comparisons of paediatric and adult sporotrichosis in Jilin Province,China

Sporotrichosis is endemic in Jilin Province of Northeast China. While paediatric cases make a substantial contribution to the epidemiological profile of sporotrichosis, the differences in the epidemiology and clinical manifestations of sporotrichosis between paediatric and adult patients remain unclear. We retrospectively reviewed the clinical records of 2968 cases of sporotrichosis (2113 adult patients aged ≥ 15 years and 855 paediatric patients aged < 15 years) over a nine-year period (01/01/2010-31/12/2018-). All the patients were diagnosed with sporotrichosis based on fungal culture of material from a skin lesion. In paediatric patients, the male:female ratio was 1.3:1, the incidence of sporotrichosis in the cold seasons was high (79.0%), most lesions occurred in the facial region (92.2%), and there was a preponderance of fixed cutaneous sporotrichosis (86.8%). In adult patients, the male:female ratio was 1:2.4, the incidence of sporotrichosis in the cold seasons was 66.0%, most lesions affected the extremities (48.6%) and the face (44.9%), and fixed cutaneous sporotrichosis was common (69.3%). The results indicate there were significant differences in the distribution of paediatric and adult sporotrichosis patients by sex, season with the highest occurrence of sporotrichosis, lesion sites and clinical types. Our results suggest that the epidemiology and clinical manifestations between paediatric and adult patients were different, and the route of infection of sporotrichosis in children may differ from that of adults in Jilin Province.     

不同地区申克孢子丝菌基因分型研究

目的:探讨申克孢子丝菌基因分型特征与菌种来源的关系。方法:采用随机扩增DNA指纹方法(RAPD)对来源于不同地区的31株申克孢子丝菌临床分离株进行DNA多态性分析。结果:①筛选出4个具有较好扩增片段的引物。②31株菌的DNA带型不完全相同,具有一定的遗传变异性,与菌株的地区来源有关。③同一患者不同部位取材的菌株间DNA型可不同。结论:随机扩增DNA多态性方法可用于申克孢子丝菌的DNA分型,其DNA带型与菌株的地区来源有关。     

The NLRP3 inflammasome contributes to host protection during Sporothrix schenckii infection

Sporotrichosis is a mycosis caused by fungi from the Sporothrix schenckii species complex, whose prototypical member is Sporothrix schenckii sensu stricto. Pattern recognition receptors (PRRs) recognize and respond to pathogen‐associated molecular patterns (PAMPs) and shape the following adaptive immune response. A family of PRRs most frequently associated with fungal recognition is the nucleotide‐binding oligomerization domain‐like receptor (NLR). After PAMP recognition, NLR family pyrin domain‐containing 3 (NLRP3) binds to apoptosis‐associated speck‐like protein containing a caspase recruitment domain (ASC) and caspase‐1 to form the NLRP3 inflammasome. When activated, this complex promotes the maturation of the pro‐inflammatory cytokines interleukin‐1β (IL‐1β) and IL‐18 and cell death through pyroptosis. In this study, we aimed to evaluate the importance of the NLRP3 inflammasome in the outcome of S. schenckii infection using the following three different knockout (KO) mice: NLRP3^−/−, ASC^−/− and caspase‐1^−/−. All KO mice were more susceptible to infection than the wild‐type, suggesting that NLRP3‐triggered responses contribute to host protection during S. schenckii infection. Furthermore, the NLRP3 inflammasome appeared to be critical for the ex vivo release of IL‐1β, IL‐18 and IL‐17 but not interferon‐γ. Additionally, a role for the inflammasome in shaping the adaptive immune response was suggested by the lower frequencies of type 17 helper T (Th17) cells and Th1/Th17 but not Th1 cells in S. schenckii‐infected KO mice. Overall, our results indicate that the NLRP3 inflammasome links the innate recognition of S. schenckii to the adaptive immune response, so contributing to protection against this infection.     

Unusual fatty acid in Sporothrix schenckii

Sporothrix schenckii was isolated from a specimen from a 75-year-old woman with lymphatic sporotrichosis on the left forearm. A mass of fungi was cultured in liquid Sabouraud dextrose broth for three months. Crude lipids were extracted from the cultured fungal mass. Total fatty acids and free fatty acids were isolated, purified, and then analyzed using thin-layer chromatography, gas liquid chromatography, and mass spectrometry. Total fatty acid composition consisted of seven molecular species of C15:0 (2.5%), C16:1 (2.5%), C16:0 (64.5%), 2-Me-C16:0 (5.1%), C17:0 (2.0%), C18:1 (18.0%) and C18:0 (5.3%). Free fatty acid composition consisted of eight species of C14:0 (2.0%), C15:1 (4.1%), C16:1 (7.5%), C16:0 (68.5%), C17:0 (0.6%), C18:2 (2.0%), C18:1 (14.5%) and of C18:0 (0.9%). 2-Me-C16:0 was detected in the fungus for the first time.     

Sporotrichosis in north-east India

Reports on the occurrence of sporotrichosis in some parts of north-east India are scarce. We report here five cases of lymphocutaneous sporotrichosis from north-east India, including one from Sikkim State and four from distant places in the north-eastern part of West Bengal. All patients were full or part-time farmers or gardeners. Diagnosis of sporotrichosis was confirmed by isolation of Sporothrix schenckii in culture and in vitro conversion of the isolates to yeast form. The cases were treated with 50% solution of potassium iodide.     

Role of TLR-2 and Fungal Surface Antigens on Innate Immune Response Against Sporothrix schenckii

Sporotrichosis is an infection caused by the dimorphic fungus Sporothrix schenckii. Toll-like receptors (TLRs) play an important role in immunity, since they bind to pathogen surface antigens and initiate the immune response. However, little is known about the role of TLR-2 and fungal surface antigens in the recognition of S. schenckii and in the subsequent immune response. This study aimed to evaluate the involvement of TLR-2 and fungal surface soluble (SolAg) and lipidic (LipAg) antigens in phagocytosis of S. schenckii and production of immune mediators by macrophages obtained from WT and TLR-2^-/- animals. The results showed that TLR-2^-/- animals had had statistical lower percentage of macrophages with internalized yeasts compared to WT. SolAg and LipAg impaired phagocytosis and immunological mediator production for both WT and TLR-2^-/-. The absence of TLR-2 led to lower production of the cytokines TNF-α, IL-1β, IL-12 and IL-10 compared to WT animals. These results suggest a new insight in relation to how the immune system, through TLR-2, recognizes and induces the production of mediators in response to the fungus S. schenckii.