Failure to detect Bartonella henselae infection in synovial fluid from sufferers of chronic arthritis

Bartonella henselae causes granulomatous and indolent infection in the immu ne competent human, and angioproliferation in the context of persistent inf ection and impaired immunity. This bacterium is found in up to 40% of house hold cats, from which humans acquire it by either a cat scratch or a bite ( hence the name, cat-scratch disease). Approximately 5% of Australian and US blood donors have serological evidence of past infection, but most associa ted illnesses are mild or subclinical. A number of lines of evidence prompt ed us to consider a relationship between rheumatoid arthritis (RA) and Bart onella infection. These include epidemiological associations with household pet exposure; apparent responsiveness of some RA cases to tetracycline the rapy; the granulomatous and angioproliferative nature of Bartonella lesions ; the insidiousness and high seroprevalence of this infection in the commun ity; and even reported Bartonella infection mimicking juvenile RA. In a sma ll group of patients with chronic arthritides, we found no direct evidence of humoral antibodies to, nor of persistent infection with, Bartonella hens elae in synovial fluid. While larger and more invasive studies are likely t o provide more confident exclusions of this hypothesis, this suggests that persistent Bartonella infection is unlikely to play a major role in RA.