Drug sensitivity testing is important for determining the effectiveness of antimicrobial agents targeted at specific pathogens. This process guides the treatment decisions thus avoiding the misuse of antibiotics and helping to fight against antimicrobial resistance. However, the traditional methods of drug sensitivity testing can be time-consuming. In this article, we shall explore the various cost-effective methodologies associated with drug sensitivity testing which can help labs and healthcare providers to get the results in the most affordable manner.

Introduction to Drug Sensitivity Testing

Drug sensitivity testing, also known as susceptibility testing, assesses the effectiveness of drugs against microorganisms. This testing is essential for guiding the treatment of bacterial and fungal infections. By identifying the most effective antibiotic or antifungal agent, healthcare providers can tailor treatments to individual patients, reducing the risk of resistance development and ensuring better clinical outcomes.

Methods of Drug Sensitivity Testing 

Disk Diffusion Method

Among the test techniques used for drug sensitivity testing, the disk diffusion method or the Kirby-Bauer test stands out as one of the oldest and most popular techniques. In this method, disks impregnated with antibiotics are placed on an agar plate inoculated with the test organism. After incubation, the diameters of the zones of inhibition around the disks are measured to determine the susceptibility of the organism to the antibiotics.

Broth Microdilution Method

Broth microdilution method is considered as the reference standard method for determining the minimum inhibitory concentration of an antimicrobial agent. It works by serially diluting antibiotics into a liquid growth medium and inoculating the medium with the test organism. The MIC is the least concentration of an antibiotic agent that can inhibit the visible growth of the organism.

E-test Strips

E-test strips combine the simplicity of the disk diffusion test with the quantitative precision of broth microdilution. The test strip comprises a gradient of antibiotic concentrations and is placed on an agar plate which is inoculated with the test organism. The point at which the ellipse of growth inhibition intercepts the strip is the MIC.

Automated Systems

Automated systems such as VITEK 2 and BD Phoenix have the added advantage of being able to provide results for drug sensitivity testing quickly and accurately. The tools perform broth microdilution testing by applying the latest technology and with the provision of results in very short periods. While the initial investment in these systems is high, it lowers the cost of labor and increases throughput, hence cost-effective in a high-volume setting.

Colorimetric Assays

Colorimetric assays, such as the resazurin microtiter assay, are tests based on observable color changes that indicate the increase or decrease of the microbial population during antibiotic susceptibility testing. Essentially, the reduction of colorimetric dye by metabolically active cells provides a visual output on growth inhibition.

Agar Dilution Method

In the agar dilution method, varying concentrations of antibiotics are incorporated into agar plates that have been inoculated with the test organism. With this method, very accurate values of MIC are obtained, and it is generally applicable to most organisms.

Innovations in Cost-Effective Testing

Recent advances promise cheaper and more accessible ways of performing drug sensitivity testing. Some of the noted ones among them are:

Paper-Based Microfluidic Devices

Paper-based microfluidic devices are a very promising low-cost alternative for drug sensitivity testing. The devices can be easily applied for the test since they involve channels and wells made from patterned paper. Channels and detection zones are patterned on paper using techniques like wax printing. A liquid sample is applied to an inlet that flows through hydrophilic channels by capillary action. Reagents in detection zones react with the sample, to produce visible color changes. These devices require minimal use of reagents and can be easily transported and stored. Therefore, the technology enjoys wide use in low-resource functionalities and field applications.

Smartphone-Based Detection

Smartphone-based detection devices make use of the pervasion of smartphones for reading and analysis of the result from a test. These systems use the phone camera and custom software to capture images and interpret data from tests such as disk diffusion or microdilution. 

Lab-on-a-Chip Technologies

Lab-on-a-chip technologies miniaturize multiple laboratory processes on one single chip. It is much cheaper as tests for drug sensitivity can be done using very small amounts of reagents and samples. These technologies, though still under development, offer remarkable promise for making cost-effective diagnostics.

At Microbe Investigations Switzerland, we understand the importance of balancing cost-efficiency with accuracy in drug sensitivity testing. Our advanced testing services are designed to provide reliable and economical solutions, helping pharmaceutical companies and healthcare providers achieve optimal outcomes without compromising on quality. Our expert team utilizes state-of-the-art technology and methodologies to deliver precise results, ensuring your testing processes are both effective and affordable.

To learn more about our cost-effective approaches to drug sensitivity testing, or to schedule a consultation to discuss your specific needs, please contact our specialists today.