Wednesday, September 7, 2011

DNA microarray and antibiotics resiostence detection

Microarrays represent a tool for parallel detection of thousands of
different DNA sequences in a single experiment. Combination of PCR-
based amplification steps with subsequent microarray-based detection of
amplicons on a microarray facilitates the sensitive and highly specific
detection of PCR products. Besides that, hybridization to oligonucleotide
capture probes enables the detection of resistance mutations without the
need for additional sequencing (Strommenger et al., 2007).DNA microarrays apply nucleic acid molecules (commonly
referred to as probes) that are immobilized on solid supports, tonterrogate nucleic acid molecules (referred to as targets) from a sample.
They make use of the unique feature of nucleic acids to form duplex
structures among complementary molecules and have evolved from
membrane-based blotting methods (Southern et al. 1999).
In contrast to the use of Nylon or nitrocellulose membranes as
support materials, the introduction of rigid, impermeable, flat substrates,
such as glass, enabled the drastic miniaturization of DNA arrays and
facilitated fluorescence-based detection and automated array manufacture
and handling (Schena et al. 1995; Southern et al. 1999).
Examples of microarrays developed to detect antibiotic resistance:
Several oligonucleotide microarrays have been developed to detect
multiple antibiotic resistance genes and mutations (Frye et al., 2006).
• In 2001, Hamels et al. (2001) published the first report on a
diagnostic microarray for the identification of nosocomially
important MRSA isolates. This array enabled the detection of the
species-specific marker femA, together with mecA, the gene for
PBP2a, which is responsible for methicillin resistance.
• Lee et al. (2002) described a microarray for the detection of
different types of β-lactam antibiotic resistance genes in gram-
negative bacteria (including PSE, OXA, FOX, MEN, CMY, rEM,
SHY, OXY, AmpC).
• An oligonucleotide microarray system which enables the
simultaneous detection of 10 different antibiotic resistance genes
and mutations (mecA, aacA-aphD, tetK, tetM, vat(A), vat(B),
vat(C), erm(A), erm(C), grlA mutation) in multiresistant S. aureus
was developed by Strommenger et al. (2007).

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