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Detection of Pneumococcus from whole blood, buffy coat and serum samples by PCR during bacteremia in mice
P Salo1, K Laitinen, M Leinonen
1National Public Health Institute, Department in Oulu, Finland.
Abstract:
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.
Insights
Whole blood is the optimal specimen for detecting pneumococcal bacteremia using polymerase chain reaction (PCR) in mice. This method proved more sensitive than blood cultures and other sample types for identifying pneumococcal DNA.
Area of Science:
- Microbiology
- Molecular Biology
- Animal Models
Background:
- Pneumococcal bacteremia is a significant cause of morbidity and mortality.
- Accurate and rapid detection of pneumococcal bacteremia is crucial for effective treatment.
- Polymerase chain reaction (PCR) offers a sensitive method for detecting microbial DNA.
Purpose of the Study:
- To evaluate different specimens for the detection of pneumococcal bacteremia in mice using PCR.
- To compare PCR-based detection with traditional blood culture methods.
- To determine the optimal specimen type for pneumococcal DNA detection via PCR.
Main Methods:
- Whole blood, leukocyte fraction (buffy coat), and serum were collected from mice at 3 and 12 hours post-challenge.
- Mice were challenged intraperitoneally with Streptococcus pneumoniae.
- Samples were analyzed using PCR for pneumococcal DNA and compared to blood culture results.
Main Results:
- Pneumococcal culture positivity increased from 27% at 3 hours to 77% at 12 hours post-challenge.
- All whole blood samples were PCR-positive at both 3 and 12 hours.
- Leukocyte fraction showed 67% and 100% PCR positivity at 3 and 12 hours, respectively.
- Serum samples demonstrated 40% PCR positivity at 3 hours and 90% at 12 hours.
Conclusions:
- Whole blood is the superior specimen for detecting pneumococcal bacteremia in mice using PCR.
- PCR detection in whole blood provides higher sensitivity and earlier detection compared to serum or leukocyte fractions.
- The findings support the use of whole blood PCR for rapid and accurate diagnosis of pneumococcal bacteremia in animal models.