Effect of Doxycycline or Orbifloxacin Administration on Bartonella spp and Hemoplasma Assay Results in Naturally Exposed Cats

The purpose of this study was to evaluate the effect of successful treatment for Bartonella spp, Mycoplasma hemofelis or Candidatus Mycoplasma haemominutum infection of cats on results of diagnostic test results commonly available to veterinary practitioners through commercial diagnostic laboratories. Evidence of infection or exposure to Bartonella spp, M hemofelis or Candidatus M. haemominutum was detected in 15 cats with fever. Doxycycline (50 mg) or orbifloxacin (22.7 mg) were administered empirically by mouth for 28 days to 12 cats with laboratory evidence of Bartonella spp infection alone and three cats with laboratory evidence of Bartonella spp and M. hemofelis or Candidatus M. haemominutum co-infection with the laboratory tests repeated on Day 35 and 58 (10 cats) or Day 35 alone (5 cats). While clinical illness in all 15 cats rapidly resolved, all nine cats that were PCR positive for Bartonella spp on Day 0 were still PCR positive on Day 35. Four of the six cats tested on Day 58 were still positive. Only one cat that was positive for Bartonella spp antibodies detected by ELISA on Day 0 was negative on Day 35 and Day 58. Of the 3 cats that were PCR positive for M. hemofelis or ‘Candidatus M. haemominutum’ on Day 0, only 1 cat (Candidatus M. haemominutum’) was PCR positive on Day 35 or Day 58. The results of the study support the recommendation that cats with suspected clinical bartonellosis should be evaluated concurrently by PCR (or culture) and serology. There appears to be little indication for following Bartonella spp assay results within the first 30 days using the treatment protocols described herein.