Biology:Sporothrix brasiliensis

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Short description: Species of fungus

Sporothrix brasiliensis
Scientific classification edit
Domain: Eukaryota
Kingdom: Fungi
Division: Ascomycota
Class: Sordariomycetes
Order: Ophiostomatales
Family: Ophiostomataceae
Genus: Sporothrix
Species:
S. brasiliensis
Binomial name
Sporothrix brasiliensis
Marimon, Gené, Cano & Guarro (2007)

Sporothrix brasiliensis is a fungus that is commonly found in soil. It is an emerging fungal pathogen that is causing disease in humans and cats mainly in Brazil and other countries in South America.

Similar to other species in Sporothrix genus, this fungus causes the disease sporotrichosis. However, it has been observed that more severe disease results from infection by Sporothrix brasiliensis compared to other species.[1] The fungus is a thermally dimorphic fungus as it is found in the mycelium phase at room temperature and as yeast in the warmer temperatures of host bodies.[2]

Morphology

The two morphologies displayed by Sporothrix brasiliensis are a hyphal form which occurs in the environment and a yeast form which occurs at higher temperatures (36 - 37 °C) such as within the bodies of mammals.

Hyphal Phase

The hyphal form of S.brasiliensis occurs at room temperature. Melaninization level of the hyphal form can vary from light (albino) to dark (pigmented) phenotypes. Sympodial conidia are obovoid shaped with a glassy (hyaline) appearance while sessile conidia are dark colored and globose.[3]

Yeast Phase

The yeast form of S.brasiliensis occurs at higher temperatures. Micro-morphologically the yeast takes the shape of an elongated cigar.[3]

Habitat and Ecology

S.brasiliensis is commonly found in the soil and is saprophytic in its mycelium phase. The main vector of the pathogen is thought to be cats which spread the fungus through bites and scratches as well as lesions found on the bodies of cats.[2][4] It is believed that the origin of the pathogen comes from the ingestion of rats by cats where it zoonotically spread to humans.

Epidemiology

Sporothrix brasiliensis was first described in the Southeastern region of Brazil and sporotrichosis caused by the fungus was endemic to the region prior to 1990. However disease has quickly spread to other parts of Brazil and neighboring countries in South America with reported cases in Argentina , Paraguay, Bolivia, Columbia and Panama.[2][5] A review in 2015 reported that of 5,814 cases of sporotrichosis in Brazil, 88% of cases were caused by S.brasiliensis.[6] The fungus has been isolated from intestinal and feline fecal samples which suggest that feces from infected cats may contaminate soil and contribute to the spread of the disease.[7]

Sporotrichosis

Cutaneous lesions caused by sporotrichosis on cat's paw

Sporotrichosis is traditionally associated with subcutaneous exposure of Sporothrix propagules typically through minor injury while coming in contact with plants, soil, or organic matter.[8] However zoonotic transmission through cats mainly through scratching, biting, or coming in contact with skin lesions has been the main mode of transmission for S.brasiliensis, constituting the current epidemic in South America.[2][4] While cutaneous infection is most common, pulmonary sporotrichosis from inhaling conidia, and disseminated sporotrichosis can also occur, primarily in individuals who are immunocompromised.[8] It is believed that S.brasiliensis is more virulent than other species that cause sporotrichosis like S.schenckii and results in larger, longer lasting lesion with a higher degree of local and systemic inflammation as demonstrated on mice.[1] A report in May 2020 reported a fatal case of pulmonary sporotrichosis caused by S.brasiliensis in a patient with no history of skin trauma or immunocompromise further supporting the notion of increased fungal virulence in S.brasiliensis relative to S.schenckii. [9]

Treatment

Sporotrichosis caused by S.brasiliensis is difficult to treat due to resistance to main antifungal therapies. Current treatment recommendations for both felines and humans mainly include the antifungal drug itraconazole.[2][7] Alternative therapies include the use of terbinafine and potassium iodine for cutaneous infection, and amphotericin B for severe pulmonary and disseminated forms of infection.[2]

Structure of itraconazole

Issues with Treatment

While itraconazole has shown moderate effectiveness against S.brasiliensis, strains of the fungus that display resistance against the drug have been documented.[10] In addition, the treatment of felines is particularly difficult as care requires prolonged intervals of time daily and many cats fail to respond well to therapies. As such abandonment of treatments is frequent and typically occurs with the observed healing of skin lesions.[7][11] Due to this the recurence of disease can typically occur with higher severity while increasing the chances of antifungal resistance strain development. Failure to complete treatment regimens also contributes to the continued spread of the disease to other cats and humans.

References

  1. ↑ 1.0 1.1 Batista-Duharte, Alexander; Téllez-Martínez, Damiana; Roberto de Andrade, Cleverton; Portuondo, Deivys Leandro; Jellmayer, Juliana Aparecida; Polesi, Marisa Campos; Carlos, Iracilda Zeppone (2018-12-01). "Sporothrix brasiliensis induces a more severe disease associated with sustained Th17 and regulatory T cells responses than Sporothrix schenckii sensu stricto in mice" (in en). Fungal Biology 122 (12): 1163–1170. doi:10.1016/j.funbio.2018.08.004. ISSN 1878-6146. PMID 30449354. https://www.sciencedirect.com/science/article/pii/S1878614618302228. 
  2. ↑ 2.0 2.1 2.2 2.3 2.4 2.5 Etchecopaz, Alejandro; Toscanini, María A.; Gisbert, Amelia; Mas, Javier; Scarpa, Miguel; Iovannitti, Cristina A.; Bendezú, Karla; Nusblat, Alejandro D. et al. (2021-02-26). "Sporothrix brasiliensis: A Review of an Emerging South American Fungal Pathogen, Its Related Disease, Presentation and Spread in Argentina". Journal of Fungi 7 (3): 170. doi:10.3390/jof7030170. ISSN 2309-608X. PMID 33652625. 
  3. ↑ 3.0 3.1 Marimon, Rita; Cano, Josep; Gené, Josepa; Sutton, Deanna A.; Kawasaki, Masako; Guarro, Josep (October 2007). "Sporothrix brasiliensis, S. globosa, and S. mexicana, Three New Sporothrix Species of Clinical Interest" (in en). Journal of Clinical Microbiology 45 (10): 3198–3206. doi:10.1128/JCM.00808-07. ISSN 0095-1137. PMID 17687013. 
  4. ↑ 4.0 4.1 Rodrigues, Anderson Messias; Teixeira, Marcus de Melo; Hoog, G. Sybren de; Schubach, Tânia Maria Pacheco; Pereira, Sandro Antonio; Fernandes, Geisa Ferreira; Bezerra, Leila Maria Lopes; Felipe, Maria Sueli et al. (2013-06-20). "Phylogenetic Analysis Reveals a High Prevalence of Sporothrix brasiliensis in Feline Sporotrichosis Outbreaks" (in en). PLOS Neglected Tropical Diseases 7 (6): e2281. doi:10.1371/journal.pntd.0002281. ISSN 1935-2735. PMID 23818999. 
  5. ↑ "Sporothrix brasiliensis | Fungal Diseases | CDC" (in en-us). 2021-10-25. https://www.cdc.gov/fungal/diseases/sporotrichosis/brasiliensis.html. 
  6. ↑ Zhang, Y.; Hagen, F.; Stielow, B.; Rodrigues, A.M.; Samerpitak, K.; Zhou, X.; Feng, P.; Yang, L. et al. (2015-12-23). "Phylogeography and evolutionary patterns in Sporothrix spanning more than 14 000 human and animal case reports". Persoonia - Molecular Phylogeny and Evolution of Fungi 35 (1): 1–20. doi:10.3767/003158515X687416. PMID 26823625. PMC 4713101. https://www.ingentaconnect.com/content/nhn/pimj/2015/00000035/00000001/art00001;jsessionid=4t3ih6jdjrq9r.x-ic-live-02. 
  7. ↑ 7.0 7.1 7.2 Gremião, Isabella Dib Ferreira; Martins da Silva da Rocha, Elisabeth; Montenegro, Hildebrando; Carneiro, Aroldo José Borges; Xavier, Melissa Orzechowski; de Farias, Marconi Rodrigues; Monti, Fabiana; Mansho, Wilson et al. (2021-03-01). "Guideline for the management of feline sporotrichosis caused by Sporothrix brasiliensis and literature revision" (in en). Brazilian Journal of Microbiology 52 (1): 107–124. doi:10.1007/s42770-020-00365-3. ISSN 1678-4405. PMID 32990922. PMC 7966609. https://doi.org/10.1007/s42770-020-00365-3. 
  8. ↑ 8.0 8.1 Mahajan, Vikram K. (2014-12-29). "Sporotrichosis: An Overview and Therapeutic Options" (in en). Dermatology Research and Practice 2014: e272376. doi:10.1155/2014/272376. ISSN 1687-6105. PMID 25614735. 
  9. ↑ do Monte Alves, Manoella; Pipolo Milan, Eveline; da Silva-Rocha, Walicyranison Plinio; Soares de Sena da Costa, Alexandre; Araújo Maciel, Bruno; Cavalcante Vale, Pedro Henrique; de Albuquerque, Paulo Roberto; Lopes Lima, Soraia et al. (2020-05-26). "Fatal pulmonary sporotrichosis caused by Sporothrix brasiliensis in Northeast Brazil". PLOS Neglected Tropical Diseases 14 (5): e0008141. doi:10.1371/journal.pntd.0008141. ISSN 1935-2727. PMID 32453723. 
  10. ↑ Rodrigues, Anderson Messias; de Hoog, G. Sybren; de Cássia Pires, Débora; Brihante, Raimunda Sâmia Nogueira; da Costa Sidrim, José Júlio; Gadelha, Marcos Fabio; Colombo, Arnaldo Lopes; de Camargo, Zoilo Pires (2014-04-23). "Genetic diversity and antifungal susceptibility profiles in causative agents of sporotrichosis". BMC Infectious Diseases 14 (1): 219. doi:10.1186/1471-2334-14-219. ISSN 1471-2334. PMID 24755107. 
  11. ↑ Chaves, A. R.; de Campos, M. P.; Barros, M. B. L.; do Carmo, C. N.; Gremião, I. D. F.; Pereira, S. A.; Schubach, T. M. P. (March 2013). "Treatment Abandonment in Feline Sporotrichosis - Study of 147 Cases: Feline Sporotrichosis Abandonment Therapy" (in en). Zoonoses and Public Health 60 (2): 149–153. doi:10.1111/j.1863-2378.2012.01506.x. PMID 22898261. https://onlinelibrary.wiley.com/doi/10.1111/j.1863-2378.2012.01506.x. 

Wikidata ☰ Q10676463 entry



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