Evaluation of a Novel Light Scattering Methodology for the Detection of Pathogenic Bacteria in Urine.

ABSTRACT

BACKGROUND: Urine culture, the gold standard for detecting and identifying bacteria in urine, is one of the highest volume tests in many microbiology laboratories. The inability to accurately predict which patients would benefit from culture leads not only to monopolization of laboratory resources, but also to unnecessary antimicrobial exposure as patients receive empirical treatment for suspected or presumed urinary tract infections (UTI) while awaiting culture results. A common approach to decrease unnecessary urine culture is screening samples using urinalysis (UA) parameters to determine those that should proceed to culture (reflex). In this study, we compared the performance of a novel uropathogen detection method to urinalysis for purposes of UTI screening. METHODS: Urine specimens submitted for culture (n = 194) were evaluated by urinalysis and a novel light scattering device (BacterioScan 216Dx UTI System) capable of detecting the presence of bacteria in urine. Sensitivity and specificity for prediction of a positive urine culture by UA and 216Dx were determined relative to urine culture results. A positive urine culture was defined as growth in culture of one or two uropathogens at concentrations of ≥50,000 CFU/mL. RESULTS: 194 urine samples were evaluated by UA, 216Dx, and urine culture. The 216Dx demonstrated a 100% [95%CI 88.43%-100.0%] sensitivity and 81.71% [95%CI 74.93%-87.30%] specificity for the detection of bacteriuria, vs UA with a sensitivity of 86.67% [95%CI 69.28%-96.24%] and specificity of 71.95% [95%CI 64.41%-78.68%] when compared to urine culture (diagnostic reference method). CONCLUSIONS: BacterioScan allows for an alternative method of screening with satisfactory sensitivity and improved specificity that may facilitate a reduction of unnecessary cultures. Additional studies are required to determine if a concomitant decrease in inappropriate antibiotic use can be realized with the 216Dx technology.