The polymerase chain reaction(PCR) assay was used for rapid diagnosis from blood and organ samples experimentally infected with Listeria monocytogenes. This method used a pair of primers based on a unique region in the 16S rRNA sequence of L monocytogenes.
Procedure A was based on dilution of the blood sample followed by lysis of bacterial cell and direct analysis of the lysate with PCR. In artificially infected blood samples with L monocytogenes, it was possible to detect fewer than 40 cells per ml of blood. However, L monocytogenes was detected low rates on infected organs by the direct PCR.
In procedure B, enrichment cultivation was used to increase numbers of bacteria before lysis and PCR. L monocytogenes was detected from 23 samples of 24 liver and spleen, respectively, and 18 samples of 24 blood were found to be positive by PCR on a subset of 72 organ samples, whereas L monocytogenes were detected on 63 organ samples in classical culture technique. It was required to analyze including enrichment steps were 6h and 18h on the procedure A and B, respectively.
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