Detection of pneumococcus from whole blood, buffy coat and serum samples by PCR during bacteremia in mice

Whole blood, purified leukocyte fraction and serum were investigated as specimens for the detection of pneumococcal bacteremia by polymerase chain reaction (PCR) in mice. The PCR findings were compared to the blood culture results. Samples were taken from animals 3 and 12 h after intraperitoneal bacterial challenge. The pneumococcal culture was positive in 27% and 77% of blood samples at 3 and 12 h after challenge, respectively. All whole blood samples were positive by PCR at both time points. Of the buffy coat samples, two of the three pools were PCR-positive at 3 h and all pools at 12 h after bacterial challenge. In the serum sample group, only 40% of the sera were PCR-positive at 3 h, while at 12 h 90% of the samples were PCR-positive. According to these results, whole blood seems to be the best specimen for the detection of pneumococcal DNA by PCR in bacteremic mice.