Examples of individual hybridisation results. Experiments using E. coli (A) and S. aureus (B) were done as dilution series near their limit of detection. E. coli shows a much lower detection limit of 10 bacteria per assay than S. aureus with 103 bacteria per assay. Even at lowest sensitivity level specific hybridisation patterns can still be obtained. Grey, black and white bars represent specific and non-specific signals as well as positive controls (BSrev is the hybridisation control and pr_FW and pr_FW T7 are PCR amplification controls). Error bars represent the mean of 6 replicate spots on the microarray. These figures only display intensities of spot signals which were flagged positive automatically by the GenePix Software. However for statistical analysis (quantile normalisation) all signals were evaluated. Results were controlled by visual inspection of image files.