A Method for Processing Digital Images of Colorimetric Biochips for Quantitative Determination of Bacterial Antibiotic Resistance Genes

Methods of molecular genetic analysis based on the colorimetric biochip technology have shown their effectiveness in identifying antibiotic resistance genes in bacteria. For the quantitative determination of nucleic acids, a comparative study of methods for converting digital color images of biochips into monochrome black-and-white versions using RGB and CMYK color models has been carried out. A 19-mer single-stranded oligonucleotide and two model mRNAs corresponding to the genes of two types of clinically relevant beta-lactamases (CTX-M and NDM) were studied as objects. The widest range of staining intensity and the best analytical characteristics for the determination of all types of studied nucleic acids were obtained using the red channel of the RGB color model. The detection limits were 0.10 +/- 0.02 pmol/mu L for the 19-mer oligonucleotide, and 3.0 +/- 0.2 and 8.0 +/- 0.6 amol/mu L for mRNA of beta-lactamases CTX-M-116 and NDM-1, respectively. The developed method can be used for the quantification of genes responsible for the multiple resistance of bacteria to antimicrobial drugs.