| Autor: |
Caterino-de-Araujo, Adele, de los Santos-Fortuna, Elizabeth, Zandoná-Meleiro, Mônica Cristina, Calore, Edenilson Eduardo, Calore, Nilda Maria Perez |
| Zdroj: |
Pathology - Research and Practice; January 2000, Vol. 196 Issue: 5 p321-327, 7p |
| Abstrakt: |
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 equias the causative agent of pleuro-pulmonary infection. Immunochemical characterization of the R. equiisolate 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. equifor 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. equistrains 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 hyphothesis 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. equiinfection in human beings that suggests a relationship between pleural malakoplakia and the virulence-associated antigen of 20-kDa. |
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