''Bartonella'' is a
genus of
Gram-negative bacteria. It is the only genus in the family Bartonellaceae.
, ''Bartonella'' species can infect healthy people, but are considered especially important as
opportunistic pathogens.
''Bartonella'' species are transmitted by
vectors such as
ticks,
fleas,
sand flies
Sandfly (or sand fly) is a colloquial name for any species or genus of flying, biting, blood-sucking dipteran (fly) encountered in sandy areas. In the United States, ''sandfly'' may refer to certain horse flies that are also known as "greenhea ...
, and
mosquitoes. At least eight ''Bartonella'' species or
subspecies
In biological classification, subspecies is a rank below species, used for populations that live in different areas and vary in size, shape, or other physical characteristics (morphology), but that can successfully interbreed. Not all species ...
are known to infect humans.
''
Bartonella henselae'' is the organism responsible for
cat scratch disease.
History
''Bartonella'' species have been infecting humans for thousands of years, as demonstrated by ''
Bartonella quintana'' DNA in a 4000-year-old tooth.
The genus is named for
Alberto Leonardo Barton Thompson (1871–October 26, 1950), a
Peruvian scientist.
Infection cycle
The currently accepted model explaining the infection cycle holds that the transmitting vectors are
blood-sucking arthropods and the
reservoir hosts are
mammal
Mammals () are a group of vertebrate animals constituting the class Mammalia (), characterized by the presence of mammary glands which in females produce milk for feeding (nursing) their young, a neocortex (a region of the brain), fur or ...
s. Immediately after infection, the bacteria colonize a primary niche, the
endothelial cells. Every five days, some of the ''Bartonella'' bacteria in the endothelial cells are released into the blood stream, where they infect
erythrocytes. The bacteria then invade a
phagosomal
In cell biology, a phagosome is a vesicle formed around a particle engulfed by a phagocyte via phagocytosis. Professional phagocytes include macrophages, neutrophils, and dendritic cells (DCs).
A phagosome is formed by the fusion of the ce ...
membrane inside the erythrocytes, where they multiply until they reach a critical population density. At this point, they simply wait until they are taken up with the erythrocytes by a blood-sucking arthropod.
Though some studies have found "no definitive evidence of transmission by a tick to a
vertebrate host,"
''Bartonella'' species are well-known to be transmissible to both animals and humans through various other vectors, such as fleas, lice, and sand flies.
Recent studies have shown a strong correlation between tick exposure and
bartonellosis
Bartonellosis is an infectious disease produced by bacteria of the genus ''Bartonella''.
''Bartonella'' species cause diseases such as Carrión's disease, trench fever, cat-scratch disease, bacillary angiomatosis, peliosis hepatis, chronic bacter ...
,
including human bartonellosis. ''Bartonella'' bacteria are associated with cat-scratch disease, but a study in 2010 concluded, "Clinicians should be aware that . . . a history of an animal scratch or bite is not necessary for disease transmission."
All current ''Bartonella'' species identified in canines are human pathogens.
Pathophysiology
''Bartonella'' infections are remarkable in the wide range of symptoms they can produce. The course of the diseases (acute or chronic) and the underlying pathologies are highly variable.
Treatment
Treatment is dependent on which species or strain of ''Bartonella'' is found in a given patient. While ''Bartonella'' species are susceptible to a number of standard antibiotics ''
in vitro''—
macrolides and
tetracycline, for example—the efficacy of antibiotic treatment in immunocompetent individuals is uncertain.
Immunocompromised patients should be treated with antibiotics because they are particularly susceptible to systemic disease and bacteremia. Drugs of particular effectiveness include
trimethoprim-sulfamethoxazole,
gentamicin
Gentamicin is an antibiotic used to treat several types of bacterial infections. This may include bone infections, endocarditis, pelvic inflammatory disease, meningitis, pneumonia, urinary tract infections, and sepsis among others. It is not e ...
,
ciprofloxacin, and
rifampin; ''B. henselae'' is generally resistant to
penicillin
Penicillins (P, PCN or PEN) are a group of β-lactam antibiotics originally obtained from ''Penicillium'' moulds, principally '' P. chrysogenum'' and '' P. rubens''. Most penicillins in clinical use are synthesised by P. chrysogenum using ...
,
amoxicillin, and nafcillin.
Epidemiology
Homeless intravenous drug users are at high risk for ''Bartonella'' infections, particularly ''B. elizabethae''. ''B. elizabethae'' seropositivity rates in this population range from 12.5% in
Los Angeles, to 33% in
Baltimore, Maryland
Baltimore ( , locally: or ) is the most populous city in the U.S. state of Maryland, fourth most populous city in the Mid-Atlantic, and the 30th most populous city in the United States with a population of 585,708 in 2020. Baltimore was ...
, 46% in
New York City, and 39% in
Sweden
Sweden, formally the Kingdom of Sweden,The United Nations Group of Experts on Geographical Names states that the country's formal name is the Kingdom of SwedenUNGEGN World Geographical Names, Sweden./ref> is a Nordic country located on ...
.
Phylogeny
The currently accepted taxonomy is based on the
List of Prokaryotic names with Standing in Nomenclature (LPSN).
The phylogeny is based on whole-genome analysis.
References
External links
* August 30. 2014
''People's Pharmacy Radio Podcast: Bartonella''website
* May 18, 201
''Bartonella spp. bacteremia and rheumatic symptoms in patients from Lyme disease-endemic region''
Medical publication, North Carolina State University, Raleigh, North Carolina, USA.
''Bartonella''
genomes and related information a
PATRIC
a Bioinformatics Resource Center funded b
NIAID
{{Taxonbar, from1=Q135006, from2=Q4865719
Bartonellaceae
Bacteria genera
Tropical diseases