Molecular diagnosis of Bartonella spp. in HIV-infected patients

Abstract

The genus Bartonella includes more than 30 species of bacteria, of which B. bacilliformis, B. quintana and B. henselae are the three most important species in human diseases. Bacterial transmission occurs through arthropods such as fleas, lice or sand flies, as well as scratching or biting of cats, depending on the bacterial species involved. Included in the spectrum of diseases caused by these bacteria are cat scratch disease, bacillary angiomatosis, chronic bacteremia, lymphadenopathy, trench fever, neurological disorders, infectious endocarditis, and liver peliosis. Bartonella spp. infections have been described in animals from different regions of Brazil. However, the prevalence of infections in humans has been less studied. The diagnosis of Bartonella infection in humans is particularly difficult in clinical practice because, besides a lack of familiarity in several physicians with the disease, laboratory diagnostic tests are rarely available. These methods consist of serological tests, histopathological examination, culture and molecular tests. Each one has its advantages and limitations. HIV-immunosuppressed patients may have severe infections with B. quintana or B. henselae. Therefore, timely diagnosis and implementation of therapy are of paramount importance in preventing infection complications. In this context, the present project is based on the hypothesis that the real prevalence of human infections with Bartonella spp. in Brazil is inaccurately known, especially in patients living with HIV. This is a cross-sectional study that aims to evaluate the prevalence of Bartonella spp. in patients with HIV, using different methodologies. Seroprevalence will be evaluated by semi-quantitative IgG antibodies against B. quintana and B. henselae. Bacterial culture of blood samples will be performed in culture media specifically prepared and under conditions recommended for isolation of Bartonella spp. Real time polymerase chain reaction will be performed in all blood samples and those cultures that isolated bacteria. In positive isolates will also be performed sequencing and phylogenetic analysis. These methods allow, besides the identification of species in a more sensitive way, genotyping studies of Brazilian isolates of Bartonella spp. in the context of HIV immunosuppression. The results of the present study may contribute to the development of new lines of research, especially those of clinical and epidemiological aspects and will contribute, especially, the diagnosis of bartonellosis in immunosuppressed patients. (AU)