DNA Microarray for Antibiotic Susceptibility Testing
Most bacteria are resistant to multiple antibiotics and other drugs, reducing the effectiveness of clinical drug therapy. Microarray analysis has been widely used to detect antibiotic resistance genes in metagenomic samples isolated from various clinical sources. Creative Biolabs offers well-established and innovative One-Stop-Shop live biotherapeutic product (LBP) development solutions. We can also support the strain safety assessment of LBP for regulatory approval.
Overview of DNA Microarray
The microarray technology was developed in the 1990s, with a variety of probes fixed to a supporting surface to detect specific genes. DNA microarrays are powerful tools for studying all aspects of prokaryotes, as they allow simultaneous monitoring of the expression of all genes in any bacterium. The essence of microarray technology is a parallel hybridization of a mixture of labeled nucleic acids called targets with thousands of individual nucleic acid species called probes that can be identified by their spatial location in a single experiment. The positions of specific probes on the array are called spots or features. The probe is fixed to a solid scaffold and the target is applied as a solution to the fluorescently labeled array for hybridization.
Fig.1 Main steps in transcription analysis with microarrays. (Ehrenreich, 2006)
Types of DNA Microarrays
Currently, there are three types of DNA microarrays widely used :(1) microarrays, in which probes are directly synthesized in situ on the surface of the chip. What the other two types have in common is that separate synthesis probes are printed on special glass slides. Depending on the nature of the probes, they can be classified into (2) double-stranded DNA microarrays and (3) oligonucleotide DNA microarrays.
They are produced by the chemical synthesis of the oligonucleotides directly on the coated quartz surface of the array. This technology allows very high feature densities. For this reason, they are called high-density oligonucleotide arrays.
There are two different technologies: contact printers and contactless printers. Contact printers recognize features through various types of pins. Noncontact printers use bubble jet or inkjet technology analogous to computer printers.
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Double-stranded DNA Microarrays
There are two main types of probes used by DNA microarray printers: double-stranded DNA and oligonucleotides. Double-stranded DNA is usually amplified by polymerase chain reaction (PCR). The advantages of double-stranded DNA microarrays are high hybridization specificity, sensitivity, and low cost.
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Oligonucleotide DNA Microarrays
The use of synthetic oligonucleotides as probes is an alternative to double-stranded DNA. Their initial disadvantage of lower specificity and sensitivity as a result of short oligonucleotides of 25-bp length has been overcome by using longer probes with a length of 50 to 70 bp. This short probe length is a major advantage of oligoprobes.
DNA microarrays and DNA chips are other promising techniques for screening susceptibility. The DNA array uses a cDNA fragment probe on a nylon membrane. Each DNA chip has a glass or silicon platform to attach the probe. Specific hybridization between labeled probe and target and its recognition help to determine resistance. Microarray technology addresses the limitations of traditional drug resistance gene detection techniques because of its simplicity, specificity, and high throughput, allowing multiple specific genes to be detected in a single reaction. DNA microarray techniques have been reported to simultaneously detect genes in multiple drug-resistant isolates.
The development and validation of microbiota-management tools for probiotics and LBP is complex. Creative Biolabs is flexible to meet the unique needs of LBP client projects. With our extensive experience in microbial analysis, we can help you answer critical questions during product development. If you are interested in our DNA microarrays services for AST, please contact us for further information.
Reference
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Ehrenreich, A. DNA microarray technology for the microbiologist: an overview. Applied microbiology and biotechnology. 2006, 73(2): 255-273.
For Research Use Only. Not intended for use in food manufacturing or medical procedures (diagnostics or therapeutics). Do Not Use in Humans.
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