Total bacterial DNA, total <i>Escherichia coli</i> and total <i>Lactobacillus</i> 16S rDNA copy numbers from DNA extracted from seven Gram stained and unstained slides spiked with <i>Escherichia coli</i> and <i>Lactobacillus</i>.

<p>Slides were spiked with mixture of mixture of 10?8 and 10?5 cfu/ml of <i>E.coli</i> and <i>Lactobacillus</i>. For each pair one replicate was Gram stained while the other was left unstained. After DNA extraction from stained and unstained slides, samples were preamplified using 8F-1492R degenerate bacterial primers for different cycles and analyzed for 16S rDNA copies using species and genera specific quantitative PCR.