Genus consists of 19 species and subspecies.
Humans the reservoir for 2 species of B. quintana and B bacilliformis.
Associated with bacillary angiomatosis, Oroya fever, trench fever and endocarditis.
Rik factors associated with B. quintana, B. bacilliformis and B. henselae include homelessness, exposure to human lice or B. quintana, cat scratches with B. henselae and visits the Andes where the sand-fly vector is found for B. bacilliformis.
Bartonella is a genus of Gram-negative bacteria, that are facultative intracellular parasites.
Mostly opportunistic pathogens, but can infect healthy people.
Bartonella species are transmitted by vectors: ticks, fleas, sand flies, and mosquitoes.
There are at least eight Bartonella species or subspecies that infect humans.
Bartonella species cause diseases such as Carrión’s disease, trench fever, cat-scratch disease, bacillary angiomatosis, peliosis hepatis, chronic bacteremia, endocarditis, chronic lymphadenopathy, and neurological disorders.
Bartonella henselae is the organism responsible for cat scratch disease.
Transmitting vectors are blood-sucking arthropods and the reservoir hosts are mammals.
After infection, the bacteria colonize endothelial cells.
Every five days, some of the Bartonella bacteria in the endothelial cells are released into the blood stream, where they infect erythrocytes.
Inside the erythrocytes, they reach a critical population density, and they simply wait until they are taken up with the erythrocytes by a blood-sucking arthropod.
Bartonella species are transmissible to humans through various other vectors, such as fleas, lice, and sand flies.
Of the more than 30 known Bartonella species, B. quintana transmitted by body live, and B. henselae transmitted by cats with claws that are contaminated with infected flea feces cause the most clinical infections.
There is a strong correlation between tick exposure and bartonellosis.
Bartonella bacteria are associated with cat-scratch disease.
Homeless intravenous drug users are at high risk for Bartonella infections, particularly B. elizabethae.
Bartonella infections produce a wide range of symptoms they can produce.
Bartonellosis course of the disease highly variable.
B. bacilliformis causes Carrion’s disease.
B. quintana causes trench fever, bacillary angiomatosis, and endocarditis.
B. clarridgeiae-incidental domestic cat- Cat scratch disease
B. henselae Incidental Domestic cat Cat scratch disease.
Bartonella endocarditis can lead to vasculitis manifested as glomerulonephritis.
Treatment
Treatment is dependent on which species or strain of Bartonella is found.
Bartonella species are susceptible to a number of standard antibiotics-macrolides and tetracycline.
Antibiotic effectiveness of antibiotic treatment in immunocompetent individuals is uncertain.
Immunocompromised patients are treated with antibiotics because they are particularly susceptible to systemic disease and bacteremia.
Effective antibiotics: trimethoprim-sulfamethoxazole, gentamicin, ciprofloxacin, and rifampin.
B. henselae is generally resistant to penicillin, amoxicillin, and nafcillin.
Homeless intravenous drug users are at a particularly high risk for Bartonella infections.
B. elizabethae seropositivity rates in the homeless drug population ranges from 12.5% in Los Angeles to 46% in New York City.
B. bacilliformis causes Carrion’s disease, and Patients can develop two clinical phases: an acute septic phase and a chronic eruptive phase associated with skin lesions.
B. bacilliformis causes a sudden, potentially life-threatening infection associated with high fever and hemolytic anemia and transient immunosuppression.
B. bacilliformis is considered the most deadly species.
It has a death rate of up to 90% during the acute phase, which typically lasts two to four weeks.
Peripheral blood smears show aniso and macrocytosis with many bacilli adherent to red blood cells.
Thrombocytopenia can be very severe.
Neurologic manifestations include: altered mental status, agitation, coma, ataxia, spinal meningitis, or paralysis.
Neurologic manifestations is seen in 20% of patients with acute infection, in which there is an about 50% mortality.
An overwhelming infection complication occurs with mainly Enterobacteriaceae, particularly Salmonella (both S. typhi and S. non-typhi, as well as reactivation of toxoplasmosis and other opportunistic infections .
Chronic manifestations consists of a benign skin eruption with raised, reddish-purple nodules,
The bacterium can be seen microscopically, if a skin biopsy is silver stained.
Cats usually become immune to cat scratch disease infection.
Humans may also acquire cat scratch fever through flea or tick bites from infected dogs, cats, coyotes, and foxes.
Trench fever, produced by Bartonella quintana infection, is transmitted by the human body louse Pediculus humanus corporis.
B bacilliformis associated with Oroya fever in persons in Peru, Ecuador and Colombia.
B bacilliformis and B quintana transmitted by arthropods.
Usually accompanied by high fever.
Liver and gut lesions are common in disseminated infection.