Highly sensitive bacterial susceptibility test against penicillin using parylene-matrix chip.

Area of Science:

• Biochemistry
• Analytical Chemistry
• Microbiology

Background:

• Beta-lactamase enzymes confer resistance to beta-lactam antibiotics by hydrolyzing them.
• Accurate quantification of this hydrolysis is crucial for antibiotic susceptibility testing.
• Traditional methods may face challenges with low molecular weight analyte quantification.

Purpose of the Study:

• To develop a highly sensitive bacterial antibiotic susceptibility test.
• To quantitate beta-lactamase-mediated hydrolysis of penicillin using a novel chip.
• To assess the minimum bacterial cell count required for reliable resistance screening.

Main Methods:

• Utilized a Parylene-matrix chip in conjunction with MALDI-TOF mass spectrometry.
• Developed a beta-lactamase assay to measure penicillin hydrolysis into penicilloic acid.
• Tested the assay on both antibiotic-resistant and antibiotic-susceptible Escherichia coli strains.

Main Results:

• The Parylene-matrix chip successfully quantified penicillin and penicilloic acid with minimal interference.
• The assay demonstrated high sensitivity in detecting beta-lactamase activity.
• A minimum of 1000 Escherichia coli cells were sufficient for antibiotic resistance screening.

Conclusions:

• The Parylene-matrix chip coupled with MALDI-TOF MS provides a sensitive and reliable method for bacterial antibiotic susceptibility testing.
• This approach minimizes interference from matrix fragments, improving analyte quantification.
• The assay is efficient, requiring a low number of bacterial cells for effective resistance screening.