Bartonella

Bartonella is a genus of Gram-negative bacteria. It is the only genus in the family Bartonellaceae.<ref name="BrennerO'Connor1993">Template:Cite journal</ref><ref name=Peters>Template:Cite journal</ref> Facultative intracellular parasites, Bartonella species can infect healthy people, but are considered especially important as opportunistic pathogens.<ref name=Baron>Template:Cite book</ref> Bartonella species are transmitted by vectors such as fleas, sand flies, and mosquitoes. At least eight Bartonella species or subspecies are known to infect humans.<ref name=Chomel_2005>Template:Cite journal</ref>

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.<ref name="tooth">Template:Cite journal</ref> The genus is named for Alberto Leonardo Barton Thompson (1871–October 26, 1950), a Peruvian scientist.<ref>Template:Cite journal</ref>

Infection cycle

Though some studies have found "no definitive evidence of transmission by a tick to a vertebrate host,"<ref name="Angelakis">Template:Cite journal</ref><ref name="Telford">Template:Cite journal</ref> Bartonella species are well-known to be transmissible to both animals and humans through various other vectors, such as fleas, lice, and sand flies.<ref name="Billeter">Template:Cite journal</ref><ref>Vilcins I, Kosoy M, Old JM, Deane EM (2009). Bartonella-like DNA detected in Ixodes ticks (Acari: Ixodida) infesting koalas (Phascolarctos cinereus) in Victoria, Australia. Vector-Borne & Zoonotic Diseases. 9(5), 499-503. DOI: 10.1089/vbz.2008.0132 </ref> 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."<ref name="Mosbacher">Template:Cite journal</ref> All current Bartonella species identified in canines are human pathogens.<ref name="Chomel_2006">Template:Cite journal</ref>

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.<ref name=Rolain_2004>Template:Cite journal</ref>

Bartonella pathophysiology in humans
Species	Human reservoir or incidental host?	Animal reservoir	Pathophysiology	Distribution
B. bacilliformis	Reservoir		Causes Carrion's disease (Oroya fever, Verruga peruana)	Peru, Ecuador, and Colombia
B. quintana	Reservoir	Japanese macaque	Causes trench fever, bacillary angiomatosis, and endocarditis	Worldwide
B. clarridgeiae	Incidental	Domestic cat	Cat scratch disease
B. elizabethae	Incidental	Rat	Endocarditis
B. grahamii	Incidental	Mouse	Endocarditis and neuroretinitis
B. henselae	Incidental	Domestic cat	Cat scratch disease, bacillary angiomatosis, peliosis hepatis, endocarditis, bacteremia with fever, neuroretinitis, meningitis, encephalitis	Worldwide
B. koehlerae	Incidental	Domestic cat
B. naantaliensis	Reservoir	Myotis daubentonii
B. vinsonii	Incidental	Mouse, dog, domestic cat	Endocarditis, bacteremia
B. washoensis	Incidental	Squirrel	Myocarditis
B. rochalimae	Incidental	Unknown	Carrion's disease-like symptoms
References:<ref>Template:Cite journal</ref><ref>Template:Cite journal</ref><ref>Template:Cite journal</ref><ref>Template:Cite journal</ref><ref name=Rolain_2004 />

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.<ref name=Rolain_2004 /> 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, ciprofloxacin, and rifampin; B. henselae is generally resistant to penicillin, amoxicillin, and nafcillin.<ref name=Rolain_2004 />

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,<ref>Template:Cite journal</ref> to 33% in Baltimore, Maryland,<ref>Template:Cite journal</ref> 46% in New York City,<ref>Template:Cite journal</ref> and 39% in Sweden.<ref>Template:Cite journal</ref>

Phylogeny

The currently accepted taxonomy is based on the List of Prokaryotic names with Standing in Nomenclature (LPSN).<ref name="LPSN"/> The phylogeny is based on whole-genome analysis.<ref name="Hördt">Template:Cite journal</ref>

External links

• Bartonella genomes and related information at PATRIC, a Bioinformatics Resource Center funded by NIAID
• New Bartonella Species That Infects Humans Discovered