Beyond Domestic Cats: Environmental Detection of Sporothrix brasiliensis DNA in a Hyperendemic Area of Sporotrichosis in Rio de Janeiro State, Brazil

Abstract

In Brazil, sporotrichosis has transitioned from a rural to urban disease, driven by a shift in the initiation of infection from the accidental inoculation of organic matter to the traumatic implantation of the fungus by cats. Since the emergence of zoonotic sporotrichosis caused by Sporothrix brasiliensis, investigations have largely ignored the environmental habitat of the pathogen due to its association with domestic cats. Therefore, we investigated 18 environmental samples collected from rural areas of two cities where zoonotic sporotrichosis is endemic, but where domestic cats are scarce. We utilized traditional culture methods, and samples were also examined with two molecular methods used for the clinical diagnosis of sporotrichosis: a nested-PCR targeting the ITS region and a species-specific PCR targeting the calmodulin gene. No Sporothrix colonies were identified by traditional culture methods. However, the nested-PCR and the species-specific PCR for S. brasiliensis were positive for 18 and 5 samples, respectively. Sequencing revealed that positive results with the nested-PCR were due to non-specific amplification of other Ophiostomatales DNA, rather than Sporothrix spp. Three of the five amplicons from the species-specific PCR were suitable for sequencing and confirmed the presence of S. brasiliensis DNA. Hence, we confirmed that S. brasiliensis, as with other Sporothrix species, has an environmental habitat. Our findings underscore the challenges of nested-PCR for Sporothrix environmental studies and highlight that sequencing must follow PCR protocols to definitively identify Sporothrix spp. in environmental samples.

Current Progress on Epidemiology, Diagnosis, and Treatment of Sporotrichosis and Their Future Trends

“…Higher temperatures, heavy rainfall, and flooding are associated with an increase in emerging zoonotic diseases [ 166 , 167 ]. Medically relevant Sporothrix can be detected in the soil of endemic areas where it remains for years [ 168 , 169 ], and it is interesting to hypothesize that water from floods and inundations, a phenomenon increasingly common in Brazil, may also promote the diffusion of Sporothrix propagules in the soil.…”

Trends in Molecular Diagnostics and Genotyping Tools Applied for Emerging Sporothrix Species

“…[ 1 , 6 , 7 , 8 , 9 ]. Therefore, the drivers of the emergence of pathogenicity in a genus whose core is mostly saprophytic is an intriguing phenomenon which is still poorly understood [ 10 , 11 , 12 , 13 , 14 , 15 , 16 ].…”

Special Issue “Sporothrix and Sporotrichosis 2.0”

“…However, few efforts have been carried out to understand the ecological niche of Sporothrix spp. in this geographical area [ 14 ]. Here, Almeida-Silva et al reported the isolation of 18 environmental samples from the hyperepidemic area of Rio de Janeiro, in particular from rural areas with a low cat population density, and were not capable to isolate any fungal colony with morphology similar to Sporothrix spp.…”

“…Here, Almeida-Silva et al reported the isolation of 18 environmental samples from the hyperepidemic area of Rio de Janeiro, in particular from rural areas with a low cat population density, and were not capable to isolate any fungal colony with morphology similar to Sporothrix spp. [ 14 ]. However, molecular strategies such as nested-PCR and the species-specific PCR for S. brasiliensis were positive for 18 and 5 samples, respectively [ 14 ].…”

“…[ 14 ]. However, molecular strategies such as nested-PCR and the species-specific PCR for S. brasiliensis were positive for 18 and 5 samples, respectively [ 14 ]. Further characterization of amplicons generated by the nested-PCR indicated that were false positive due to amplification of other Ophiostomatales DNA, but three of the five amplicons produced by species-specific PCR were indeed from S. brasiliensis [ 14 ].…”