title: Multiplex pathogen identification for polymicrobial urinary tract infections using biosensor technology: a prospective clinical study.
abstract: OBJECTIVE
  Rapid diagnosis of urinary tract infection would have a significant beneficial impact on clinical management, particularly in patients with structural or functional urinary tract abnormalities who are highly susceptible to recurrent polymicrobial infections. We examined the analytical validity of an electrochemical biosensor array for rapid molecular diagnosis of urinary tract infection in a prospective clinical study in patients with neurogenic bladder.
  
  
  METHODS
  The electrochemical biosensor array was functionalized with DNA probes against 16S rRNA of the most common uropathogens. Spinal cord injured patients at a Veterans Affairs hospital were recruited into the study. Urine samples were generally tested on the biosensor within 1 to 2 hours of collection. Biosensor results were compared with those obtained using standard clinical microbiology laboratory methods.
  
  
  RESULTS
  We successfully developed a 1-hour biosensor assay for multiplex identification of pathogens. From July 2007 to December 2008 we recruited 116 patients, yielding a total of 109 urine samples suitable for analysis and comparison between biosensor assay and standard urine culture. Of the samples 74% were positive, of which 42% were polymicrobial. We identified 20 organisms, of which Escherichia coli, Pseudomonas aeruginosa and Enterococcus species were the most common. Biosensor assay specificity and positive predictive value were 100%. Pathogen detection sensitivity was 89%, yielding a 76% negative predictive value.
  
  
  CONCLUSIONS
  To our knowledge we report the first prospective clinical study to successfully identify pathogens within a point of care time frame using an electrochemical biosensor platform. Additional efforts to improve the limit of detection and probe design are needed to further enhance assay sensitivity.
authors.affiliation: Department of Urology, Stanford University School of Medicine, Stanford, California 94305-5118, USA.
authors.forename: Kathleen E
authors.initials: KE
authors.lastname: Mach
authors.forename: Christine B
authors.initials: CB
authors.lastname: Du
authors.forename: Hardeep
authors.initials: H
authors.lastname: Phull
authors.forename: David A
authors.initials: DA
authors.lastname: Haake
authors.forename: Mei-Chiung
authors.initials: MC
authors.lastname: Shih
authors.forename: Ellen Jo
authors.initials: EJ
authors.lastname: Baron
authors.forename: Joseph C
authors.initials: JC
authors.lastname: Liao
mesh_terms: D015374:Biosensing Techniques; D005260:Female; D006801:Humans; D008297:Male; D011446:Prospective Studies; D001750:Urinary Bladder, Neurogenic / Q000150:complications; D014552:Urinary Tract Infections / Q000209:etiology / Q000382:microbiology*