''Bartonella'' is a
genus
Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...
of
Gram-negative
Gram-negative bacteria are bacteria that do not retain the crystal violet stain used in the Gram staining method of bacterial differentiation. They are characterized by their cell envelopes, which are composed of a thin peptidoglycan cell wall ...
bacteria
Bacteria (; singular: bacterium) are ubiquitous, mostly free-living organisms often consisting of one biological cell. They constitute a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria were among ...
. It is the only genus in the family Bartonellaceae.
Facultative intracellular parasites, ''Bartonella'' species can infect healthy people, but are considered especially important as
opportunistic
Opportunism is the practice of taking advantage of circumstances – with little regard for principles or with what the consequences are for others. Opportunist actions are expedient actions guided primarily by self-interested motives. The term ...
pathogen
In biology, a pathogen ( el, πάθος, "suffering", "passion" and , "producer of") in the oldest and broadest sense, is any organism or agent that can produce disease. A pathogen may also be referred to as an infectious agent, or simply a germ ...
s.
''Bartonella'' species are transmitted by
vectors such as
tick
Ticks (order Ixodida) are parasitic arachnids that are part of the mite superorder Parasitiformes. Adult ticks are approximately 3 to 5 mm in length depending on age, sex, species, and "fullness". Ticks are external parasites, living by ...
s,
flea
Flea, the common name for the order Siphonaptera, includes 2,500 species of small flightless insects that live as external parasites of mammals and birds. Fleas live by ingesting the blood of their hosts. Adult fleas grow to about long, a ...
s,
sand flies, and
mosquito
Mosquitoes (or mosquitos) are members of a group of almost 3,600 species of small flies within the family Culicidae (from the Latin ''culex'' meaning " gnat"). The word "mosquito" (formed by ''mosca'' and diminutive ''-ito'') is Spanish for "li ...
es. 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
''Bartonella henselae'', formerly ''Rochalimæa henselae'', is a bacterium that is the causative agent of cat-scratch disease (bartonellosis).
''Bartonella henselae'' is a member of the genus ''Bartonella'', one of the most common types of bacter ...
'' is the organism responsible for
cat scratch disease
Cat-scratch disease (CSD) or felinosis is an infectious disease that most often results from a scratch or bite of a cat. Symptoms typically include a non-painful bump or blister at the site of injury and painful and swollen lymph nodes. People m ...
.
History
''Bartonella'' species have been infecting humans for thousands of years, as demonstrated by ''
Bartonella quintana
''Bartonella quintana'', originally known as ''Rochalimaea quintana'', and "''Rickettsia quintana''", is a bacterium transmitted by the human body louse that causes trench fever. This bacterial species caused outbreaks of trench fever affecting 1 ...
'' DNA in a 4000-year-old tooth.
The genus is named for
Alberto Leonardo Barton Thompson (1871–October 26, 1950), a
Peru
, image_flag = Flag of Peru.svg
, image_coat = Escudo nacional del Perú.svg
, other_symbol = Great Seal of the State
, other_symbol_type = Seal (emblem), National seal
, national_motto = "Fi ...
vian scientist.
Infection cycle
The currently accepted model explaining the infection cycle holds that the transmitting vectors are
blood-sucking
Hematophagy (sometimes spelled haematophagy or hematophagia) is the practice by certain animals of feeding on blood (from the Greek words αἷμα ' "blood" and φαγεῖν ' "to eat"). Since blood is a fluid tissue rich in nutritious pr ...
arthropod
Arthropods (, (gen. ποδός)) are invertebrate animals with an exoskeleton, a Segmentation (biology), segmented body, and paired jointed appendages. Arthropods form the phylum Arthropoda. They are distinguished by their jointed limbs and Arth ...
s 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
The endothelium is a single layer of squamous endothelial cells that line the interior surface of blood vessels and lymphatic vessels. The endothelium forms an interface between circulating blood or lymph in the lumen and the rest of the vessel ...
. Every five days, some of the ''Bartonella'' bacteria in the endothelial cells are released into the blood stream, where they infect
erythrocytes
Red blood cells (RBCs), also referred to as red cells, red blood corpuscles (in humans or other animals not having nucleus in red blood cells), haematids, erythroid cells or erythrocytes (from Greek ''erythros'' for "red" and ''kytos'' for "holl ...
. 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 cell m ...
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
Vertebrates () comprise all animal taxa within the subphylum Vertebrata () ( chordates with backbones), including all mammals, birds, reptiles, amphibians, and fish. Vertebrates represent the overwhelming majority of the phylum Chordata, ...
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,
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
''In vitro'' (meaning in glass, or ''in the glass'') studies are performed with microorganisms, cells, or biological molecules outside their normal biological context. Colloquially called "test-tube experiments", these studies in biology an ...
''—
macrolide
The Macrolides are a class of natural products that consist of a large macrocyclic lactone ring to which one or more deoxy sugars, usually cladinose and desosamine, may be attached. The lactone rings are usually 14-, 15-, or 16-membered. Macrol ...
s and
tetracycline
Tetracycline, sold under various brand names, is an oral antibiotic in the tetracyclines family of medications, used to treat a number of infections, including Acne vulgaris, acne, cholera, brucellosis, plague (disease), plague, malaria, and sy ...
, 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
Trimethoprim/sulfamethoxazole, sold under the brand name Bactrim among others, is a fixed-dose combination antibiotic medication used to treat a variety of bacterial infections. It consists of one part trimethoprim to five parts sulfamethoxazo ...
,
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
Ciprofloxacin is a fluoroquinolone antibiotic used to treat a number of bacterial infections. This includes bone and joint infections, intra abdominal infections, certain types of infectious diarrhea, respiratory tract infections, skin inf ...
, and
rifampin
Rifampicin, also known as rifampin, is an ansamycin antibiotic used to treat several types of bacterial infections, including tuberculosis (TB), ''Mycobacterium avium'' complex, leprosy, and Legionnaires’ disease. It is almost always used tog ...
; ''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
Amoxicillin is an antibiotic medication used to treat a number of bacterial infections. These include middle ear infection, strep throat, pneumonia, skin infections, and urinary tract infections among others. It is taken by mouth, or less c ...
, 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
Los Angeles ( ; es, Los Ángeles, link=no , ), often referred to by its initials L.A., is the largest city in the state of California and the second most populous city in the United States after New York City, as well as one of the world' ...
, to 33% in
Baltimore, Maryland
Baltimore ( , locally: or ) is the List of municipalities in Maryland, most populous city in the U.S. state of Maryland, fourth most populous city in the Mid-Atlantic (United States), Mid-Atlantic, and List of United States cities by popula ...
, 46% in
New York City
New York, often called New York City or NYC, is the List of United States cities by population, most populous city in the United States. With a 2020 population of 8,804,190 distributed over , New York City is also the L ...
, 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
List of Prokaryotic names with Standing in Nomenclature (LPSN) is an online database that maintains information on the naming and taxonomy of prokaryotes, following the taxonomy requirements and rulings of the International Code of 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