Studies in Phylogeny, Development of Rapid IdentificationMethods, Antifungal Susceptibility, and Growth Rates of Clinical Strains of Sporothrix schenckii Complex in Japan

Genotyping of intraspecies polymorphisms of Sporothrix globosa using partial sequence of mitochondrial DNA

Restriction fragment length polymorphism (RFLP) of mitochondrial DNA (mtDNA) had been used for molecular identification of Sporothrix spp., which is the causative fungi of sporotrichosis and the most prevalent deep-seated dermatomycosis. Also, mtDNA-RFLP had been used to investigate the molecular epidemiology of sporotrichosis. While the current standard for molecular diagnosis is performed by sequence analysis of the calmodulin gene (CAL), correspondence between the results from CAL and mtDNA is of diagnostic and epidemiological interest. Here, we investigated the correspondence between CAL and mtDNA used for molecular identification of Sporothrix globosa and S. schenckii, which are two major species. We also investigated and propose molecular markers suitable to describe the epidemiology of S. globosa, which is considered as a species with few intraspecific polymorphisms. Eighty-seven strains morphologically identified as S. schenckii sensu lato were investigated. They were identified as group A (17 types, 17 strains) or B (14 types, 70 strains) by mtDNA-RFLP. Partial sequences of CAL, internal transcribed spacer, and spacer between atp9 and cox2 genes of mtDNA of these strains were determined. All group A strains corresponded to S. schenckii, and group B to S. globosa. The sequences of the amplicons targeted on the spacer region in mtDNA of S. globosa ranged 510-515 bp in length and exhibited 10 molecular variations, whereas CAL indicated seven molecular variations. In conclusion, most of the S. schenckii sensu lato strains isolated from Japanese sporotrichosis patients were confirmed as S. globosa, because group B, which comprised the majority of strains, matched perfectly with S. globosa by the CAL sequencing study. We proposed sequence variations in the spacer between atp9 and cox2 genes of mtDNA as a suitable molecular epidemiological marker for S. globosa.

Molecular identification of Sporothrix species in a hyperendemic area in Peru

To date, there have been no molecular typing studies to identify the Sporothrix species circulating in Abancay, a hyperendemic area of sporotrichosis in Peru. To identify six clinical isolates of the Sporothrix schenckii complex from Abancay, Peru, we used PCR-sequencing of the calmodulin gene, and a phylogenetic analysis was conducted with these and additional sequences from GenBank. All clinical isolates were identified as S. schenckii (sensu stricto). Phylogenetic analysis revealed that the six clinical isolates from Abancay, Peru clustered in a clade along with sequences from Costa Rica, Iran, South Africa, and four other sequences from Peru. These findings reveal the presence of S. schenckii (sensu stricto) in Abancay, Peru.

Molecular epidemiology of Sporothrix schenkii isolates in Malaysia

Sporothrix schenkii is a dimorphic fungus that causes infections in both humans and animals. We report on 25 S. schenkii isolates collected in 2017 from humans and cats clinically diagnosed with sporotrichosis, in Malaysia. These isolates were phenotypically identified as S. schenkii sensu lato and further defined as S. schenckii sensu stricto based on partial calmodulin gene sequence. Isolates from both humans and cats were genotypically identical but displayed phenotypic variation. Phylogenetic analyses based on partial calmodulin sequence showed that the Malaysian isolates clustered with global S. schenkii sensu stricto strains, in particular, of the AFLP type E. This analysis also revealed that partial calmodulin sequence alone was sufficient for classifying global S. schenckii sensu stricto strains into their respective AFLP types, from A to E. The genetically conserved S. schenkii sensu stricto species isolated from humans and cats is suggestive of a clonal strain present in Malaysia. To the best of our knowledge, this is the first report on molecular identification of Sporothrix schenkii strains from human infections in Malaysia. Further studies are required in order to elucidate the clonal nature of Malaysian S. schenkii isolates. Our findings indicate the presence of a predominant S. schenkii genotype in the environment, causing infections in both cats and humans in Malaysia.

Phenotypic and molecular characterisation of Sporothrix globosa of diverse origin from India

Sporotrichosis is one of the neglected tropical diseases causing subcutaneous chronic granulomatous lesion by thermally dimorphic fungi belonging to Sporothrix species. Sporothrix brasiliensis, Sporothrix mexicana and Sporothrix globosa are the common pathogenic species. In Asian countries, S. globosa constitutes nearly 99.3% of all Sporothrix species. We studied 63 cases of sporotrichosis of geographically diverse origin from India and Sporothrix isolates were characterised for its growth in different media, temperatures, ability to assimilate sugars and antifungal susceptibility profile. Molecular characterization was performed by sequencing of the calmodulin (CAL), beta tubulin (BT) and translational elongation factor 1-alpha (TEF-1α) and typing by fluorescent amplified fragment length polymorphism (FAFLP). In patients who presented with fixed (49.2%), lymphocutaneous lesions (23.8%), in 26.9% the details were not known, none had systemic dissemination. All the isolates tested were Sporothrix globosa and that could grow up to 35 °C and unable to grow at and beyond 37 °C. The assimilation of sucrose, ribitol and raffinose helps in identifying S. globosa. Sequences of CAL or BT or TEF-1α can differentiate S. globosa from other species in the complex. FAFLP results exhibited low genetic diversity. No correlation was noted between genotypes and clinical presentation, or geographic distribution. Itraconazole, terbinafine and posaconazole showed good in vitro antifungal activity against S. globosa whereas fluconazole and micafungin had no activity. S. globosa of Indian origin is relatively less pathogenic than other pathogenic Sporothrix species as it does not cause systemic dissemination and in the diagnostic laboratory, incubation of the cultures below 37 °C is essential for effective isolation.

The Diagnosis of Fungal Neglected Tropical Diseases (Fungal NTDs) and the Role of Investigation and Laboratory Tests: An Expert Consensus Report

The diagnosis of fungal Neglected Tropical Diseases (NTD) is primarily based on initial visual recognition of a suspected case followed by confirmatory laboratory testing, which is often limited to specialized facilities. Although molecular and serodiagnostic tools have advanced, a substantial gap remains between the desirable and the practical in endemic settings. To explore this issue further, we conducted a survey of subject matter experts on the optimal diagnostic methods sufficient to initiate treatment in well-equipped versus basic healthcare settings, as well as optimal sampling methods, for three fungal NTDs: mycetoma, chromoblastomycosis, and sporotrichosis. A survey of 23 centres found consensus on the key role of semi-invasive sampling methods such as biopsy diagnosis as compared with swabs or impression smears, and on the importance of histopathology, direct microscopy, and culture for mycetoma and chromoblastomycosis confirmation in well-equipped laboratories. In basic healthcare settings, direct microscopy combined with clinical signs were reported to be the most useful diagnostic indicators to prompt referral for treatment. The survey identified that the diagnosis of sporotrichosis is the most problematic with poor sensitivity across the most widely available laboratory tests except fungal culture, highlighting the need to improve mycological diagnostic capacity and to develop innovative diagnostic solutions. Fungal microscopy and culture are now recognized as WHO essential diagnostic tests and better training in their application will help improve the situation. For mycetoma and sporotrichosis, in particular, advances in identifying specific marker antigens or genomic sequences may pave the way for new laboratory-based or point-of-care tests, although this is a formidable task given the large number of different organisms that can cause fungal NTDs.

Molecular Identification, Antifungal Susceptibility, and Geographic Origin of Clinical Strains of Sporothrix schenckii Complex in Mexico

Sporotrichosis is a subcutaneous mycosis caused by Sporothrix schenckii complex. The disease has been reported worldwide. However, the incidence of the etiological agent varies in its geographic distribution. We studied 39 clinical isolates of Sporothrix schenckii from diverse regions in Mexico, collected from 1998 to 2016. Molecular identification was performed by sequence analysis of the partial calmodulin gene. In vitro antifungal susceptibility to amphotericin B (AMB), itraconazole (ITC), voriconazole (VRC), posaconazole (PSC), fluconazole (FLC), terbinafine (TRB), caspofungin (CSF), anidulafungin (ANF), and micafungin (MCF) was evaluated. Thirty-eight isolates of S. schenckii complex were divided into five supported clades in a phylogenetic tree. The predominant clinical form was lymphocutaneous (92.3%), fixed cutaneous (5.1%), and disseminated (2.5%). Terbinafine exhibited the best in vitro antifungal activity, while fluconazole was ineffective against Sporothrix schenckii complex. Our results showed diverse geographic distribution of clinical isolates in eight states; definitive identification was done by CAL gen PCR-sequencing. In Mexico, S. schenckii is considered to be an etiological agent of human sporotrichosis cases, and lymphocutaneous is the most prevalent form of the disease. This study revealed four clades of S. schenckiisensu stricto by phylogenetic analysis. Furthermore, we report one case of S. globosa isolated from human origin from the North of Mexico.

Sporotrichosis by Sporothrix schenckii senso stricto with itraconazole resistance and terbinafine sensitivity observed in vitro and in vivo: Case report

We report a case of a patient with lymphocutaneous sporotrichosis in the right upper limb. The fungus was identified as Sporothrix schenckii senso stricto by calmodulin gene sequencing. The initial treatment was itraconazole (200 mg/day), but in vitro antifungal susceptibility demonstrated high resistant to this and another six antifungals, with exception to terbinafine. The lesions did not regress with itraconazole treatment. Thus, 500 mg/day of terbinafine was prescribed and clinical cure was obtained after four months.

Comparison of two in vitro antifungal sensitivity tests and monitoring during therapy of Sporothrix schenckii sensu stricto in Malaysian cats

BACKGROUND

Feline sporotrichosis is common in Malaysia. Thermosensitivity and effects of azole treatment on fungal susceptibility are unknown.

OBJECTIVES

To evaluate thermotolerance and antifungal susceptibility of feline Malaysian Sporothrix isolates, compare microdilution (MD) and E-test results, and investigate changes in susceptibility during azole therapy.

METHODS

Sporothrix schenckii sensu stricto was isolated from 44 cats. Thermotolerance was determined via culture at 37°C for 7 days. Susceptibility to itraconazole (ITZ), ketoconazole (KTZ) and terbinafine (TRB) was assessed in 40 isolates by MD; to amphotericin B (AMB), KTZ, ITZ, fluconazole (FLC) and posaconazole (POS) by E-test. Results were statistically compared by Pearson's Product Moment. In eight ketoconazole treated cats, susceptibility testing to itraconazole and ketoconazole was repeated every two months for six months.

RESULTS

Thermotolerance was observed in 36 of 44 (82%) isolates. Assuming that isolates growing at antifungal concentrations ≥4 mg/mL were resistant, all were resistant on E-test to FLC and AMB, 11 (28%) to POS, 6 (15%) to ITZ and 1 (3%) to KTZ. On MD, 27 of 40 (68%) were resistant to TRB, 2 (5%) to ITZ and 3 (8%) to KTZ. There was no correlation between E-test and MD results (KTZ r = 0.10, P = 0.54, and ITZ r = 0.11, P = 0.48). MD values for ITZ and KTZ did not exceed 4 mg/L during KTZ therapy.

CONCLUSION

The majority of feline isolates in Malaysia are thermosensitive. Lack of correlation between E-test and MD suggests that the E-test is unreliable to test antifungal susceptibility for Sporothrix spp. compared to MD. KTZ was the antifungal drug with the lowest MIC. Prolonged KTZ administration may not induce changes in antifungal susceptibility.