Bacteria Genomes - BARTONELLA QUINTANA

Bartonella species are facultative intracellular bacteria associated with a number of emerging anthropozoonoses. They have been detected in or isolated from diverse vertebrate hosts, including humans, various intradomicillary mammals, and a wide range of wild animals, which serve as natural vertebrate hosts. Various hematophagous arthropods have been implicated in the ecoepidemiology of Bartonella species. Bartonella are a group of small, weakly-staining, Gram-negative bacteria, includes three species of human medical importance.

Bartonella quintanalives and multiplies within the gut of the body louse and then can be transmitted to humans. Transmission to people can occur by rubbing infected louse feces into abraded (scuffed) skin or into the conjunctivae (whites of the eyes).

The human pathogen Bartonella quintana causes trench fever, a disease that affected more than one million soldiers during World War I and has re-emerged among homeless individuals in some urban areas. Trench fever can be either slow or rapid in onset. In the rapid onset form, there is an incubation period of 8-30 days, after which there is a sudden development of symptoms, ncluding severe headache, myalgia and pain in the lower body from the lumbar region to the shins. Shin pain is characteristic of the disease and splenomegaly is common. Rigors were common in World War I. A short lived rash that may only last a few hours is often observed. The spleen is often enlarged. The fever associated with the disease lasts a few days followed by remission and relapse after 5-6 days. There may be several rounds of remission and relapse. In some cases, the fever is typhoid-like. Depression and neurological sequelae are common and endocarditis may be found. The disease can recur for years, so patients may need to be monitored.

Bartonella quintana has episodically emerged as a cause of infection among distinct and diverse populations during the 20th century. Although first identified during World War I B. quintana infections were rarely recognised from the end of World War II until the 1980s when the organism reemerged as an opportunistic pathogen among HIV-infected persons. In this population, B. quintana has been identified as a cause of bacillary angiomatosis, endocarditis, and bacteremia and has been isolated from AIDS patients in France and the United States. Although cases of B. quintana bacteremia among homeless persons have so far been reported only from France and Seattle, Washington, the problem is probably not confined to these locations. B. quintana is a fastidious and slow-growing bacterium that generally requires special culturing techniques for isolation. The full spectrum of disease caused by B. quintana is still unfolding.

The complete genomes for Bartonella quintana (1,581,384 bp) and Bartonella henselae (1,931,047 bp) have been sequenced and comparative studies conducted. The two pathogens maintain several similarities in being transmitted by insect vectors, using mammalian reservoirs, infecting similar cell types (endothelial cells and erythrocytes) and causing vasculoproliferative changes in immunocompromised hosts. A primary difference between the two pathogens is their reservoir ecology. Whereas B. quintana is a specialist, using only the human as a reservoir, B. henselae is more promiscuous and is frequently isolated from both cats and humans. Genome comparison elucidated a high degree of overall similarity.

Bartonella can be killed by common disinfectants including ethanol, hypochlorite, and formaldehyde however no vaccination is currently available.

References:

Proc. Natl. Acad. Sci. U S A. 101(26):9716-21 (2004)
http://www.cdc.gov/ncidod/eid/vol2no2/jackson.htm
http://www.merck.com/mrkshared/mmanual/section13/chapter159/159j.jsp
http://www.medterms.com/script/main/art.asp?articlekey=8096