Impedimetric method for measuring ultra-low E. coli concentrations in human urine

Area of Science:

• Biomedical Engineering
• Microbiology
• Sensor Technology

Background:

• Urinary tract infections (UTIs) are common, often caused by Escherichia coli (E. coli).
• Rapid and sensitive detection of E. coli in urine is critical for effective UTI diagnosis and management.
• Current diagnostic methods can be time-consuming, necessitating faster point-of-care solutions.

Purpose of the Study:

• To develop and validate an interdigitated gold microelectrode-based impedance sensor for E. coli detection in human urine.
• To monitor E. coli growth and quantify bacterial concentrations for UTI diagnosis.
• To investigate the impedance characteristics associated with bacterial growth and biofilm formation.

Main Methods:

• Fabrication of an interdigitated gold microelectrode sensor.
• Monitoring E. coli growth in human urine samples over a 12-hour period.
• Utilizing an equivalent electrical circuit model to analyze impedance variations.
• Correlating impedance changes with E. coli concentration and growth time.

Main Results:

• Successful monitoring of E. coli growth in urine over 12 hours.
• Maximum impedance changes observed at 10Hz frequency.
• Equivalent circuit analysis revealed double-layer capacitance changes due to bacterial attachment and biofilm formation.
• A strong linear correlation (R(2)>0.90) was established between impedance change and E. coli concentration.
• The sensor demonstrated high sensitivity in detecting E. coli concentrations ranging from 7×10^0 to 7×10^8 cells/ml.

Conclusions:

• The developed impedance sensor is highly sensitive and capable of detecting a wide range of E. coli concentrations in urine.
• The sensor provides a rapid and effective method for UTI diagnosis based on E. coli detection.
• Impedance analysis offers valuable insights into bacterial growth dynamics and biofilm formation on electrode surfaces.