1/2. Detection of the 20-kDa virulence-associated antigen of rhodococcus equi in malakoplakia-like lesion in pleural tissue obtained from an AIDS patient.A malakoplakia-like lesion was detected in a pleural biopsy from an AIDS patient presenting clinical and radiologic features of pneumonia. Cultures of bronchoalveolar lavage and pleural fluid evidenced rhodococcus equi as the causative agent of pleuro-pulmonary infection. Immunochemical characterization of the R. equi isolate showed the presence of a strain similar to the ATCC 33704 reference strain presenting the capsular antigen of serotype 4, and the intermediate virulence-associated antigen of 20-kDa. Histopathology of the patient's pleural biopsy showed plaques of macrophages interspersed with lymphocytes, and intracytoplasmic cocci and bacilli in macrophages, which were variably acid-fast positive. immunohistochemistry of cocci, bacilli and their degradation products resulted strongly positive when stained with a mouse monoclonal antibody (MAb) produced against the 20-kDa antigen. This finding could have important implications for the pathogenicity of R. equi for human beings, since we do not know yet all the factors involved in the formation of malakoplakia. Indeed, the results obtained in the present study, taken together with the results obtained for pigs inoculated with R. equi strains of intermediate virulence (Madarame et al. 1998), raise the possibility that most strains presenting the 20-kDa antigen may be capable of inducing malakoplakia. If this hypothesis is confirmed by immunohistochemical analysis of human pulmonary malakoplakia cases due to R. equi, the detection of this antigen may be extremely helpful in the diagnosis and treatment of such patients. This is the first report of R. equi infection in human beings that suggests a relationship between pleural malakoplakia and the virulence-associated antigen of 20-kDa.- - - - - - - - - - ranking = 1keywords = antigen (Clic here for more details about this article) |
2/2. Dermatophilus congolensis and "hairy" leukoplakia.The authors report the first human case (to our knowledge) of infection of the oral mucosa by Dermatophilus congolensis. Septate branching filaments morphologically identical to those of D. congolensis were identified in the lingual epithelium of a male homosexual employed as an animal handler. This actinomycete is the cause of dermatophilosis, a proliferative exudative dermatitis affecting many animal species. Clinical features suggested "hairy" leukoplakia (HL), a hyperkeratotic tongue lesion for which human papillomavirus (HPV) and Epstein-Barr virus (EBV) have been implicated as etiologic agents. Immunoperoxidase staining for HPV capsid antigen was negative. Direct immunofluorescent staining with a conjugate specific for D. congolensis identified the bacterial structures as those of this species while excluding morphologically similar organisms.- - - - - - - - - - ranking = 0.1keywords = antigen (Clic here for more details about this article) |