Marker Pen Device with Concentration Gradient Nib for Antibiotic Susceptibility Testing

Area of Science:

• Biomedical Engineering
• Microfluidics
• Microfabrication

Background:

• Pen-based devices offer flexible patterning, low cost, and small volumes for various applications.
• These devices are useful for pH and glucose measurement, and microchannel/microarray fabrication.
• A novel gradient nib marker pen was developed for bacteria antibiotic susceptibility testing (AST).

Purpose of the Study:

• To develop a gradient nib marker pen device for generating simultaneous, varying antibiotic concentrations.
• To assess the utility of this device in bacteria antibiotic susceptibility testing (AST).
• To establish a quantitative method for determining antibiotic concentrations based on bacterial growth inhibition.

Main Methods:

• The gradient nib marker pen deposits antibiotic gradients onto a target surface.
• Polyester fiber nibs with uniform porosity and unidirectional orientation create visible gradient patterns.
• Bacterial growth inhibition zones were analyzed using Image J software by converting images to 8-bit grayscale.

Main Results:

• The device successfully generated antibiotic gradients, leading to observable bacterial growth inhibition zones.
• Quantitative analysis of inhibition zones revealed distinct gray values corresponding to bacterial viability.
• A clear relationship was established between gray values and bacterial density within the inhibition zones.

Conclusions:

• The gradient nib marker pen provides a convenient method for quantitative antibiotic concentration determination.
• This device eliminates the need for traditional serial dilution tubes, nutrient media, and varied antibiotic dilutions.
• The method offers a streamlined approach for antibiotic susceptibility testing by correlating image gray values with bacterial density.