Description, Causes and Risk Factors:
The genus Bartonella is composed of 21 species, including B. bacilliformis, species previously classified in Rochalimaea and Grahamella genus. The genus Bartonella belongs to the alpha proteaobacteria group, close to Brucella, Afipia, Agrobacterium and Rhizobium genus. Bartonella is considered as a facultative intracellular bacterium. In vivo, B. bacilliformis and B. quintana can be observed in red blood cells in bacteriemic subjects. B. henselae, B. clarridgeiae, B. Koehlerae can be isolated and detected in blood and red blood cells (RBC) of bacteremic cats. Those bacteria also demonstrate a tropism for endothelial cells, which is correlated to their capacity to induce angioproliferatives lesions (verruga peruana for B. bacilliformis, and bacillary angiomatosis for B. henselae and B. quintana).
Formerly the type species of the genus Rochalimaea, this organism causes trench fever and in AIDS patients is associated with septicemia and endocarditis; arthropod vector is Pediculus humanus, the body louse.
Bartonella quintana, a pathogen that is restricted to human hosts and louse vectors, was first characterized as the agent of trench fever. The disease was described in 1915 on the basis of natural and experimental infections in soldiers. It is now recognized as a re-emerging pathogen among homeless populations in cities in the United States and Europe and is responsible for a wide spectrum of conditions, including chronic bacteremia, endocarditis, and bacillary angiomatosis.
Bartonella quintana is a fastidious aerobic Gram-negative (bacillus). The infection caused by this microorganism, trench fever, was first documented in soldiers during World War I, but has now been seen Europe, Asia and North Africa. Its primary vector is known to be "Pediculus humanus" variety corporis, also known as the human body louse.
Humans are the only known animal host for this bacterium in vivo. The bacterium infects endothelial cells and can infect erythrocytes by binding and entering with a large vacuole. Once inside they begin to proliferate and cause nuclear atypia (this is known as intraerythrocytic B. quintana colonization). This leads to apoptosis being suppressed, pro-inflammatory cytokines are released and vascular proliferation increases. All of these processes result in patients possessing systemic symptoms (chills, fever, diaphoresis), bacteremia and lymphatic enlargement. A major role in B.quintana infection is its lipopolysaccharide (LPS) covering which is an antagonist of the Toll-like receptor 4 (TLR-4). The reason why this infection might persist is because this organism also results in monocytes over-producing interleukin-10 (IL-10), thus weakening the immune response. B.quintana also induces lesions seen in bacillary angiomatosis that protrude into vascular lumina, often occluding blood flow. The enhanced growth of these cells is believed to be due to the secretion of angiogenic factors, thus inducing neovascularization. Release of an icosahedral particle, 40 nm in length, has been detected in cultures of quintana's close relative, henselae. This particle contains a 14-kb linear DNA segment, however its function in Bartonella pathophysiology is still unknown. In Trench Fever or B.quintana-induced endocarditis patients, Bacillary Angiomatosis lesions are also seen. Notably, endocarditis is a new manifestation of the infection, not seen in WWI troops.
The complete genomes for Bartonella quintana (1,581,384 bp) and Bartonella henselae (1,931,047 bp) have been sequenced and comparative studies conducted. The two pathogens maintain several similarities in being transmitted by insect vectors, using mammalian reservoirs, infecting similar cell types (endothelial cells and erythrocytes) and causing vasculoproliferative changes in immunocompromised hosts. A primary difference between the two pathogens is their reservoir ecology. Whereas B. quintana is a specialist, using only the human as a reservoir, B. henselae is more promiscuous and is frequently isolated from both cats and humans. Genome comparison elucidated a high degree of overall similarity.
Gangrene feet and body parts.
The clinical manifestations of B.quintana infection are highly variable. The incubation period is now known to be 5-20. The infection can start out as an acute onset of a febrile episode, relapsing febrile episodes, or as a persistent typhoidal illness. Commonly seen are maculopapular rashes, conjunctivitis, headache and myalgias, with splenomegaly being less common. Most patients present with pain in the lower legs (shins), sore muscles of the legs and back, and hyperaesthesia of the shins. Rarely is B.quintana infection fatal, unless endocarditis develops and goes untreated. Weightloss, and thrombocytopenia are sometimes also seen. Recovery can take up to a month long.
To have a definite diagnosis of infection with Bartonella quintana, requires specific tests either serological, cultures, or nucleic acid amplification techniques. To differentiate between different species, immunofluorescence assays that use mouse antisera are used, as well as DNA hybridization and restriction fragment length polymorphisms, or citrate synthase gene sequencing.
On the basis of available information, use of doxycycline, erythromycin, or azithromycin to treat B. quintana infections is recommended. Treatment of uncomplicated B. quintana bacteremia for 4-6 weeks and treatment of B. quintana endocarditis (in a person who does not undergo valve surgery) for 4-6 months are recommended, with the addition of a bactericidal agent (such as a third-generation cephalosporin or an aminoglycoside) during the initial 2-3 weeks of therapy for endocarditis.
NOTE: The above information is educational purpose. The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition.
DISCLAIMER: This information should not substitute for seeking responsible, professional medical care.
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