EFFICACY OF ENROFLOXACIN OR DOXYCYCLINE FOR TREATMENT OF BARTONELLA-HENSELAE OR BARTONELLA-CLARRIDGEIAE INFECTION IN CATS

Enrofloxacin and doxycycline are antimicrobial agents used to tret bac terial diseases of cats. In vitro susceptibility data indicate that ei ther drug should be effective against Bartonella species. In vivo effi cacies of these drugs for eradication of chronic Bartonella henselae o r Bartonella clarridgeiae infections were examined in 18 experimentall y infected cats and 25 naturally exposed cats treated with enrofloxaci n (22.7 mg given orally [PO] every 12 h [q12h] [14 days, n = 10; 28 da ys, n = 13]) or with doxycycline (25 mg PO q12h [14 days, n = 9; 28 da ys, n = 8]) or not treated (n = 3). Plasma drug concentrations were de termined in experimental cats by high-performance liquid chromatograph y. Only 23 of 43 cats enrolled ultimately met inclusion criteria. Bact eremia was eliminated for 12 to 25 weeks posttreatment in four of seve n cats receiving 14 days of enrofloxacin, five of seven cats receiving 28 days of doxycycline. Defining a negative result by blood culture a s treatment success may be erroneous; these results may reflect the in sensitivity of blood culture or the relapsing nature of Bartonella bac teremia. Our results suggest that MICs obtained with axenic media do n ot predict antimicrobial activity against intracellular Bartonella, th at a long treatment course is required to eliminate infection, and tha t duration of therapy correlates with pretreatment bacterial load. Giv en current concern about the development of antimicrobial resistance, we would reserve recommendation for treatment to cats owned by an immu nocompromised individual or as an alternative to euthanasia of a pet.