Bartonella henselae as a cause of acute-onset febrile illness in cats

Breitschwerdt, Edward B; Broadhurst, Jack J; Cherry, Natalie A

By E-test and disk diffusion assays, pradofloxacin had greater antimicrobial activity against feline B henselae isolates than enrofloxacin and azithromycin 40 and appeared to be an effective treatment for case 2; however, post-treatment BAPGM enrichment blood culture was not performed. Based upon negative culture and PCR results, cats treated with orbifloxacin appeared to clear their B henselae infections. 9 A combination of antibiotics with different modes of action, such as doxycycline and a fluoroquinolone, may be required for therapeutic elimination of B henselae in cats; however, data confirming that a combination of doxycycline and pradofloxacin (as used in case 2) eliminates B henselae infections, rather than suppressing the infection, are currently lacking. Azithromycin has often been used to treat feline bartonellosis; however, based upon in vitro testing, cat and human B henselae strains rapidly developed genetic resistance to macrolides through a single nucleotide mutation in the 23S rRNA gene. 41 Currently, no studies have investigated antimicrobial resistance in B henselae isolates obtained from azithromycin-treated cats, and there are no studies confirming the efficacy of azithromycin as a sole antibiotic for the treatment of feline bartonellosis.