What is Bartonella?

Bartonella is the name given to a genus of bacteria. Most of these are parasitic bacteria, i.e. those that exist within a host cell (i.e. intracellular). As a rule, endothelial cells or erythrocytes, i.e. red blood cells, act as host cells. Bartonella can be transmitted by a number of insects and cause various infectious diseases in humans or other vertebrates. In humans, these various forms of disease are grouped together under the name Bartonellosis. Bartonella was named after the Peruvian microbiologist Alberto Leonardo Barton.

What are the characteristics of Bartonella bacteria?

Bartonella occur in filamentous, rod or droplet form and have a scale of between 0.5 and 0.6 x 1.0 micrometres. Bartonella belong to the gram-negative bacteria and are not obligate intracellular. This means that they also live outside of cells, i.e. they can be cultivated on culture medium, for example. However, this requires haemin, a series of complex compounds made of iron ion and chloride ion.

Which infections can be caused by Bartonella?

People with a weakened immune system tend to get Bartonella infections (bartonellosis) more often. This is especially true of children and older people. Bartonella, which is usually transmitted by insects, can cause various rare diseases, such as the following:

• Bartonella alsatica: can cause endocarditis.
• Bartonellabacilliformis: can cause the so-called Carrion disease, i.e. Oroya fever and Verruga peruana.
• Bartonella clarridgeiae: can be the trigger for the so-called cat scratch disease.
• Bartonellaelizabethae: can cause endocarditis.
• Bartonellagrahamii: can cause lymphadenopathy or retinitis.
• Bartonellahenselae:  can cause the so-called cat scratch disease, bacillary angiomatosis, bacillary peliosis, bacteraemia or endocarditis.
• Bartonella koehlerae: can be the trigger for endocarditis.
• Bartonellaquintana: can cause five-day fever, bacillary angiomatosis, chronic bacteraemia or endocarditis.
• Bartonella rochalimae: can cause bacteraemia, fever or splenomegaly.
• Bartonella tamiae: can be the trigger for bacteraemia, fever, myalgia or exanthema.
• Bartonella vinsonii arupensis: can cause endocarditis or febrile illness.
• Bartonellavinsonii berkhoffii: can cause endocarditis.
• Bartonella washoensis: can be the trigger for myocarditis or meningitis.

How can you get infected with Bartonella?

Bartonella bacteria are transmitted to humans by a vector. This is possible in the following ways:

• mainly through fleas and/or clothes lice,
• through sand flies,
• through contact with flea-infested animals, for example through animal bites or scratches,
• by ticks,
• through needle bites.

What symptoms are caused by Bartonella?

A Bartonella infection can trigger various diseases and symptoms. In the case of the so-called cat disease, which can be transmitted by a flea bite, a cat bite or a scratch of the cat, a papule forms after about a week at the transmission site, which in the further course develops into a pustule. Immunocompromised individuals may develop fever and/or a rare eye disease and/or infection of the bones, liver or spleen.

According to recent case reports from a research group investigating PCR and DNA sequencing, different Bartonella pathogens can lead to chronic intravascular infection, which can last for months to years. It is also possible for neuropsychiatric symptoms to develop (Balakrishnan et al. 2016).

What complications can arise from a Bartonella infection?

A Bartonella infection can lead to the following complications:

• Inflammation of the inner lining of the heart (endocarditis),
• infectious vascular disease (basilar angiomatosis),
• Retinitis,
• Epilepsy,
• aseptic meningitis,
• Enlargement or swelling of the liver and spleen (hepatosplenomegaly),
• Tonsillitis,
• Arteritis of the brain,
• Inflammation of the brain tissue (encephalitis)

How is a Bartonella infection diagnosed?

A Bartonella can be diagnosed either by direct pathogen detection or by indirect pathogen detection. For the direct detection, a blood culture is required, which, however, has the disadvantage that it is positive in only 25 per cent of all cases, even with a so-called special procedure . However, direct detection can also be achieved by a PCR test or a cellular fatty acid profile. Indirect pathogen detection, on the other hand, is carried out by serological detection using immunofluorescence. As a rule, serological tests show a high IgG titre against Bartonella. However, it is only possible to detect genus-specific antibodies at . Differentiation between the different Bartonella pathogens is not possible.

How is a Bartonella infection treated?

In healthy people with an intact immune system, even acute illnesses clear up on their own over time and usually do not require antibiotic therapy. This is the case, for example, with an uncomplicated infection Bartonella henselae. So far, there are no medical studies that prove that the addition of antibiotics would shorten the duration of the disease.

However, if it is a complicated Bartonella infection involving, for example, the central nervous system, antibiotics should be prescribed. According to current guidelines, a treatment period of between at least four and six weeks is recommended. In people with a weakened immune system, local application of painkilling drugs (analgesics) and local heat can be used in addition . Furthermore, anti-inflammatory drugs can be used. However, cortisone, i.e. the so-called steroids, should be avoided, as these can promote the formation of fistulas.