[2][3] Facultative intracellular parasites, Bartonella species can infect healthy people, but are considered especially important as opportunistic pathogens.

Drugs of particular effectiveness include trimethoprim-sulfamethoxazole, gentamicin, ciprofloxacin, and rifampin; B. henselae is generally resistant to penicillin, amoxicillin, and nafcillin.

[14] 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,[19] to 33% in Baltimore, Maryland,[20] 46% in New York City,[21] and 39% in Sweden.

[22] The currently accepted taxonomy is based on the List of Prokaryotic names with Standing in Nomenclature (LPSN).