Evaluation and use of a nested polymerase chain reaction assay in cats experimentally infected with Bartonella henselae genotype I and Bartonella henselae genotype II

Cats have been shown to be infected with Bartonella henselae genotype I, B. henselae genotype II, and B. clarridgeiae. Feline bartonellosis infections and the strains involved in these infections are important in both veterin ary and human medicine. Nucleic acid amplification methods such as polymera se chain reaction (PCR) are being used in both research and diagnostics as tools for understanding many infectious diseases. Bartonella bacteremia in cats is detected by blood culture; however, because of the limitations of c ulture (delayed turnaround time and sensitivity limits), PCR may be a more efficient method for identifying infected cats. Three distinct PCR assays t hat could differentiate among B. henselae genotype I, B. henselae genotype II, and B. clarridgeiae were developed and used to detect as few as 3.2 org anisms. Fourteen cats experimentally infected with B. henselae genotype I a nd B. henselae genotype II were followed by bacterial culture and PCR throu gh the course of infection, including periods of primary and relapsing bact eremia. The PCR assay was positive in I I of the 14 cats for periods of 1-9 weeks after culture became negative. Of the 223 blood specimens that were culture negative, the PCR assay was positive in 38 (17%) of the specimens. Two of the 14 cats developed relapsing bacteremia. The 2 B. henselae genoty pes were amplified in the cats and the bacteremic phase of these infections as determined by PCR lasted for a longer period than previously determined by culture. Using laboratory assays such as PCR to understand the strains involved in feline bartonellosis and the course of the infection is importa nt in the understanding of these zoonotic agents.