drug susceptibility by hybridisation on a biochip. (A) The scheme of the biochip for hybridisation. The subgroups are depicted as boxes. Each subgroup corresponds to a single variable amino acid position or variable nucleotide. One gel element within each subgroup contained an oligonucleotide matching the wild-type sequence (bold circles). (B) Hybridisation of a wild-type DNA sample on the biochip. (C) Hybridisation of a DNA sample containing the following mutations indicated by arrows: gyrA (S91P, TCG > CCG) and gyrA (S95T, AGC > ACC).