Establishment of multiplex PCR for screening Escherichia coli and Salmonella in Chinese herbal medicine

The purpose is to study a multiplex PCR method for screening qualified Chinese herbal medicine granules for pharmaceutical enterprises. In this experiment, the uidA gene in Escherichia coli genome, inv A gene in Salmonella genome and 16S rDNA were used as target genes. Three pairs of primers were selected to establish and optimize the multiplex PCR system for the detection of bacteria in drugs. The amplified products were 194 bp, 362 bp and 1374 bp, respectively. The specificity of the multiplex PCR was verified by 11 strains of bacteria. The results showed that the sensitivity of multiplex PCR detection could reach $10^{3}-10^{4}$ CFU/ml at the cell level; bacteria were found in two of the six drugs tested in the market; bacteria were found in all the four drugs that did not pass the drug test, but none of the tested drugs had Escherichia coli and Salmonella. The results showed that the multiplex PCR detection method could detect Escherichia coli and Salmonella in Chinese herbal medicine granules rapidly, accurately and efficiently, which provided reference for the preliminary screening of Chinese herbal medicine granules.