Relapsing bacteremia after blood transmission of Bartonella henselae to cats.

Objectives: To determine persistence of bacteremia, pathogenicity, and immunoglobulin kinetics after blood transmission of Bartonella henselae in cats.
Animals: 18 specific-pathogen-free (SPF) cats (16 weeks old) received blood or urine from 4 adult cats (2 SPF, 2 naturally infected with B henselae).
Procedure: SPF cats were inoculated with blood IV (n = 4), blood IM (n = 4), or urine sediment IM (n = 4) from 2 bacteremic cats (donors A and B). Control cats (2/route) received inoculum from culture-negative, seronegative SPF cats (donors C and D).
Results: 6 cats (5 blood, 1 urine) were transiently febrile during the 213-day observation period. Two bacteremic cats developed CNS abnormalities. Transient anemia was the only hematologic abnormality. Bacteremia was induced in 7 of 8 blood recipients by postinoculation day (PID) 11. Urine recipients (n = 6) did not become bacteremic or seroconvert by PID 108, but when challenge exposed IV with blood, 4 of 6 became infected. All infected cats developed relapsing bacteremia. Initially, colony counts for donor-A recipients were 10(3) greater than those for donor-B recipients; however, during relapses, counts were similar. Polymerase chain reaction-restriction fragment length polymorphism analysis of 16S rRNA gene and the intergenic spacer region revealed no differences among isolates derived from recipient cats. Bartonella henselae-specific antibodies were detected between PID 15 and 18 in donor-A, compared with PID 46 and 181 in donor-B recipients. The peak geometric mean titer of donor-A recipients was 1,448, versus 406 for donor-B recipients.
Conclusions and Clinical Relevance: Blood transmission of B henselae induced subtle clinical abnormalities; the biological behavior of the 2 donor strains differed; and relapsing bacteremia can persist in conjunction with variably high antibody titers.