Diagnostic System and Process for Rapid Bacterial Infection Diagnosis

Abstract

Methods and devices for monitoring the viability of a biofilm comprising Pseudomonas aeruginosa bacteria by detecting pyocyanin are provided.

What is claimed is: 
     
         1 . A method of monitoring viability of a biofilm comprising  Pseudomonas aeruginosa  bacteria, the method comprising:
 (a) introducing a fluid sample into a microfluidic device including a working electrode and a reference electrode;   (b) performing an electrochemical measurement to detect pyocyanin in the fluid sample; and   (c) determining a concentration of pyocyanin in the fluid sample by using a previously determined correlation between pyocyanin concentration and current flow through the working electrode, the correlation comprising a linear relationship of increasing current flow with increasing pyocyanin concentration;   wherein the pyocyanin concentration is the fluid sample provides a measure of the viability of the biofilm.   
     
     
         2 . The method of  claim 1 , wherein the microfluidic device is disposed in a contact lens case, a urine bag, a urine collection cup, a medication pump, a water pipe, a bioreactor, or a water pump. 
     
     
         3 . The method of  claim 1 , further comprising estimating a number of viable cells of  Pseudomonas aeruginosa  in the biofilm based on the concentration of pyocyanin determined in step (c). 
     
     
         4 . The method of  claim 1 , wherein the electrochemical measurement is selected from the group consisting of squarewave voltammetry, linear sweep voltammetry, staircase voltammetry, cyclic voltammetry, normal pulse voltammetry, differential pulse voltammetry, and chronoamperometry. 
     
     
         5 . The method of  claim 4 , wherein the electrochemical measurement is square wave voltammetry and the current flow is measured in response to one or more square wave potentials. 
     
     
         6 . The method of  claim 1 , wherein:
 the microfluidic device comprises a second working electrode;   the working electrode is one of an oxidizing electrode and a reducing electrode, and the second working electrode is the other of the oxidizing electrode and the reducing electrode; and   the concentration of pyocyanin is measured as current flow through the oxidizing electrode and the reducing electrode.   
     
     
         7 . The method of  claim 1 , wherein 10 μL or less of the fluid sample volume is introduced. 
     
     
         8 . The method of  claim 1 , further comprising in step (a), continuously introducing the fluid sample into the microfluidic device. 
     
     
         9 . The method of  claim 8 , further comprising repeating steps (a), (b), and (c). 
     
     
         10 . The method of  claim 1 , wherein a capillary or wicking material is disposed at or near an inlet of the microfluidic device to draw the fluid sample into the device. 
     
     
         11 . The method of  claim 1 , wherein the microfluidic device is worn by a patient or implanted in a patient. 
     
     
         12 . The method of  claim 1 , wherein the microfluidic device is embedded in a wound dressing or within or adjacent to an absorbent pad for a wound dressing. 
     
     
         13 . The method of  claim 1 , wherein the fluid sample is from a human with cystic fibrosis, ventilator-associated pneumonia, a chronic wound, a burn wound, a surgical implant, or a surgical site. 
     
     
         14 . The method of  claim 11 , wherein
 the microfluidic device comprises a second working electrode;   the working electrode is one of an oxidizing electrode and a reducing electrode, and the second working electrode is the other of the oxidizing electrode and the reducing electrode; and   the concentration of pyocyanin is measured as current flow through the oxidizing electrode and the reducing electrode.   
     
     
         15 . The method of  claim 14 , further comprising applying a potential suitable for oxidizing the pyocyanin at the oxidizing electrode and a potential suitable for reducing the pyocyanin at the reducing electrode. 
     
     
         16 . The method of  claim 14 , wherein the oxidizing electrode and the reducing electrode are separated by a distance of about 200 to 100 nm. 
     
     
         17 . The method of  claim 1 , wherein the microfluidic device is in communication with a potentiostat operable to control voltage at the working electrode and the reference electrode.