The oral route in the pathogenesis of paracoccidioidomycosis: An experimental study in BALB/c mice infected with P-brasiliensis Conidia

Due to the high frequency of oral mucosal lesions observed in paracoccidioi domycosis patients, it was advocated that the infection was acquired by the traumatic implantation of the etiologic agent Paracoccidioides brasiliensi s. Although at present this theory is considered invalid, it has not yet be en excluded in experimental studies. In order to determine if intra-oral in oculation could explain the pathogenesis of paracoccidioidomycosis, 64 BALB /c mice were inoculated intra-orally with 850.000 viable P. brasiliensis co nidia into the mandibular body. Animals were sacrificed at various time int ervals up to 20 weeks and cultures were made from gingiva, lungs, spleen, a nd liver. Additionally, histopathological studies of the mandibular body we re also performed. P. brasiliensis was isolated from all gingival tissues d uring the interval 24-72 h, indicating that the infection was active. Durin g the 5-10 week period, the infection appeared to have been controlled at t he inoculation site as cultures showed a significant reduction in colony fo rming units (CFU); however, at the 15-20 week period such control was lost and the fungus was recovered once more. Dissemination to other body sites w as rare; thus, the lungs were involved in just one animal (2%), the liver i n two (3%) and the spleen in seven (11%). The infection became established as proven by positive organ cultures, but the dissemination pattern did not correspond to the one observed in humans. Based on these findings, the intra-oral traumatic route does not appear to mimic the natural history of paracoccidioidomycosis.