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Antimicrobial Susceptibility Testing

Antimicrobial susceptibility test is an experimental method to detect the sensitivity of test bacteria to antimicrobial drugs. Antimicrobial susceptibility test is mainly used to detect whether antimicrobial drugs have an inhibitory effect on pathogenic microorganisms in vitro. And then this can be used clinically to guide the selection of therapeutic drugs and to understand the changes in the resistance of common pathogens in the region. Knowledge of antibiotics that are sensitive to bacteria can transform the choice of antibiotics from empirical therapy to targeted therapy.

The basis of the drug susceptibility test method is to expose bacteria to antibiotics and observe their response ("phenotypic test") or specific genetic testing ("genetic test"). At present, the main methods of clinical microbiology laboratory for drug susceptibility testing include paper diffusion method, dilution method (including agar and broth dilution method), antibiotic concentration gradient quantitative method and automated instruments.

Our Antimicrobial Susceptibility Testing Services

  • Phenotypic method

The phenotypic method test is a test based on the exposure of bacteria to antibiotics. The most common used is the paper susceptibility test.

Drug sensitive paper is a filter paper containing a certain amount of antibacterial drugs. The paper diffusion method is to stick a drug sensitive paper on the surface of agar that has been inoculated with the test bacteria. The drug in the paper diffuses in the agar, and the concentration of the antibacterial drug decreases logarithmically as the diffusion distance increases.

High Throughput Screening (HTS) ServicesFigure 1. Schematic representation of disk diffusion assay for evaluation of antibacterial activity.

Workflow of antimicrobial susceptibility detection is as shown in Figure 1:

Step 1: Preparation of disk containing antibiotics samples.
Step 2: A bacterial culture is sowed in petri dish containing culture medium with agar.
Step 3: Disks of filter paper soaked with control solution or different concentrations of test sample are placed over the culture medium.
Step 4: After incubation, bacterial colonies will grow throughout the dish and formation of zones of growth inhibition will be observed if the sample exerted antibacterial effect. Finally, measure the zone of inhibition, calculate and analyze.

  • Genetic method

Genetic testing is a method to detect the presence of antibiotic resistance genes in bacterial genomes through polymerase chain reaction, DNA chip and loop-mediated isothermal amplification. Compared with phenotypic methods, these tests have the advantage of being direct and rapid.

Our Advantages

  • Gives a guidance for antibiotic treatment options
  • Integrate into GLP and GMP environments with full traceability
  • Produce rapid, objective interpretation of results
  • Active/proactive product line development ensures optimal drug and microbial combinations

Our Capabilities

  • Aminoglycoside
  • Beta-Lactam
  • Cephalosporin
  • Macrolide
  • Penicillin
  • Quinolone
  • Tetracycline
  • Additional Antibiotic

We combine infection and analytical expertise to provide our clients with the most powerful portfolio of antiviral and antimicrobial in vitro testing services. Facing an increasing demand for new antiviral and antimicrobial compounds for the treatment of infectious diseases, Creative Diagnostics can test these compounds in vitro to determine their potential efficacy in vivo models.


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We Are Providing Our Clients Antiviral & Antibacterial Services

Having extensive knowledge in cell biology and the application of cell-based assays to benefit clients in the drug and vaccine development industry

Offering comprehensive solutions to drive your projects to completion

Delivering prompt quotations and competitive prices

Providing quality science and personalized customer service

Antiviral Services - Creative Diagnostics

Creative Diagnostics provides expertise in antiviral (or antibacterial) assays and cell-based antiviral (or antibacterial) compound screening to other biotechnology and pharmaceutical companies.

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