Acute clinical disease in cats following infection with a pathogenic strain of Bartonella henselae (LSU16)

Bartonella henselae is the causative agent of human cat scratch disease as well as several serious sequelae of infections, including bacillary angioma tosis and bacillary peliosis, Conflicting reports describe the pathogenesis of B. henselae in the cat. In this study, we characterized a strain of B. henselae termed LSU16. This strain was isolated on rabbit blood agar from a naturally infected 10-month-old female cat during a recurrent episode of b acteremia, The bacterial species was confirmed by PCR-restriction fragment length polymorphism analysis. Nine cats were infected intradermally with 5 x 10(7) CFU of LSU16, and clinical signs, antibody responses, and bacteremi a were monitored. All nine cats developed raised, erythematous areas at the site of inoculation within 72 h postinoculation; the swelling peaked at 14 days postinfection and was not palpable by 28 days postinfection, Fever de veloped in all nine cats between 6 and 16 days postinfection and lasted for 1 to 8 days. Between 6 and 16 days postinfection, all nine cats experience d lethargy which persisted 5 to 18 days. Seven of nine eats were bacteremic by day 7, and all nine cats had become bacteremic by 14 days postinfection . Bacteremia peaked at 14 to 28 days postinfection in all cats. In six of t he nine infected cats, bacterial numbers reached nondetectable levels durin g the 7th week postinfection; however, a single animal maintained bacteremi a to 18 weeks postinfection. All nine cats developed strong antibody respon ses to B. henselae, as determined by Western blot analysis and enzyme-linke d immunosorbent assay. Subsequently, three naive cats were injected intrade rmally with blood front cats infected with LSU16 from a pure culture, and f ive naive cats were injected with feces from fleas which had been feeding o n cats infected with a pure culture of LSU16. These cats developed signs si milar to those described in the previous experiment and were euthanized at 5 weeks postinfection, We conclude that B. henselae LSU16 is a virulent str ain of B. henselae in cats and propose that the virulence of B. henselae in cats is strain dependent.