Risk Factors for Bartonella species Infection in Blood Donors from Southeast Brazil.

Bacteria from the genus Bartonella are emerging blood-borne bacteria, capable of causing long-lasting infection in marine and terrestrial mammals, including humans. Bartonella are generally well adapted to their main host, causing persistent infection without clinical manifestation. However, these organisms may cause severe disease in natural or accidental hosts. In humans, Bartonella species have been detected from sick patients presented with diverse disease manifestations, including cat scratch disease, trench fever, bacillary angiomatosis, endocarditis, polyarthritis, or granulomatous inflammatory disease. However, with the advances in diagnostic methods, subclinical bloodstream infection in humans has been reported, with the potential for transmission through blood transfusion been recently investigated by our group. The objective of this study was to determine the risk factors associated with Bartonella species infection in asymptomatic blood donors presented at a major blood bank in Southeastern Brazil. Five hundred blood donors were randomly enrolled and tested for Bartonella species infection by specialized blood cultured coupled with high-sensitive PCR assays. Epidemiological questionnaires were designed to cover major potential risk factors, such as age, gender, ethnicity, contact with companion animals, livestock, or wild animals, bites from insects or animal, economical status, among other factors. Based on multivariate logistic regression, bloodstream infection with B. henselae or B. clarridgeiae was associated with cat contact (adjusted OR: 3.4, 95% CI: 1.1-9.6) or history of tick bite (adjusted OR: 3.7, 95% CI: 1.3-13.4). These risk factors should be considered during donor screening, as bacteremia by these Bartonella species may not be detected by traditional laboratory screening methods, and it may be transmitted by blood transfusion.

Bartonella spp. bacteremia in blood donors from Campinas, Brazil.

Bartonella species are blood-borne, re-emerging organisms, capable of causing prolonged infection with diverse disease manifestations, from asymptomatic bacteremia to chronic debilitating disease and death. This pathogen can survive for over a month in stored blood. However, its prevalence among blood donors is unknown, and screening of blood supplies for this pathogen is not routinely performed. We investigated Bartonella spp. prevalence in 500 blood donors from Campinas, Brazil, based on a cross-sectional design. Blood samples were inoculated into an enrichment liquid growth medium and sub-inoculated onto blood agar. Liquid culture samples and Gram-negative isolates were tested using a genus specific ITS PCR with amplicons sequenced for species identification. Bartonella henselae and Bartonella quintana antibodies were assayed by indirect immunofluorescence. B. henselae was isolated from six donors (1.2%). Sixteen donors (3.2%) were Bartonella-PCR positive after culture in liquid or on solid media, with 15 donors infected with B. henselae and one donor infected with Bartonella clarridgeiae. Antibodies against B. henselae or B. quintana were found in 16% and 32% of 500 blood donors, respectively. Serology was not associated with infection, with only three of 16 Bartonella-infected subjects seropositive for B. henselae or B. quintana. Bartonella DNA was present in the bloodstream of approximately one out of 30 donors from a major blood bank in South America. Negative serology does not rule out Bartonella spp. infection in healthy subjects. Using a combination of liquid and solid cultures, PCR, and DNA sequencing, this study documents for the first time that Bartonella spp. bacteremia occurs in asymptomatic blood donors. Our findings support further evaluation of Bartonella spp. transmission which can occur through blood transfusions.

Bartonella clarridgeiae bacteremia detected in an asymptomatic blood donor.

Human exposure to Bartonella clarridgeiae has been reported only on the basis of antibody detection. We report for the first time an asymptomatic human blood donor infected with B. clarridgeiae, as documented by enrichment blood culture, PCR, and DNA sequencing.

Blood cell findings resembling Bartonella spp.

Some Bartonella species are able to invade red blood cells (RBC) and may cause persistent infection in the susceptible host. Use of transmission electron microscopy (TEM) demonstrates, inside erythrocytes, the typical triple-walled agents. However, when examining ultrathin sections of blood cells, the authors have, on several occasions, detected intraerythrocytic abnormalities that mimic but are not typical of Bartonella spp. Small endovesicles, pseudoinclusions, cavities, and irregular hemoglobin granules distribution, resulting in regions of increased or decreased electron density, may be observed in the erythrocytes and platelets, which may be confused with bartonellas. So far, detailed ultrastructural findings of Bartonella spp. in blood cells have not yet been described. Aiming to improve TEM interpretation of blood cells changes, in routine examination of blood sections of patients with suspected bartonellosis, the authors studied the morphological findings they have observed, and present their putative nature, according to information in the literature.

Bartonella henselae infects human erythrocytes.

Bartonella henselae, a facultative intracellular bacterium, has been known as the agent of cat scratch disease, bacillary angiomatosis, peliosis hepatis, endocarditis, and bacteremic syndrome in humans. Bartonella species can cause intraerythrocytic infections and have been isolated from the bloodstream of patients by several methods. It was demonstrated that B. bacilliformis and B. quintana infect human endothelial cells and human erythrocytes and B. henselae infects erythrocytes of cats. The aim of this study was to investigate through transmission electron microscopy whether B. henselae infects mature human erythrocytes. One red blood cell (RBC) unit received an experimentally standard strain of B. henselae. Blood aliquots were collected from the infected unit immediately after inoculation, at 30 min and 1, 5, 10, and 72 h for ultrastructural evaluation. B. henselae was seen adhering to human erythrocytes 10 h after inoculation and inside the erythrocyte after 72 h. This study demonstrates that B. henselae adheres to and invades mature human erythrocytes. The results favor the possibility that erythrocytes can serve as a primary target in Bartonella spp. infections. From this observation, further studies are warranted to prevent Bartonella spp. transfusional transmission.