Application of Laser Light Scattering Technology in Rapid Diagnosis of Urinary Tract Infections and Antimicrobial Susceptibility Testing in a Tertiary Children’s Hospital

Abstract

BackgroundTimely and accurate microbiology testing is crucial in the diagnosis and management of urinary tract infections (UTIs). The ability to rapidly screen for potential UTIs can lead to early rule out and judicious use of antimicrobial therapy. This study examines the application of laser scattering for bacterial detection and antimicrobial susceptibility testing (AST) directly from urine.MethodsResidual urine samples collected for routine culture were tested using the BacterioScan™ 216Dx™ UTI System and 216R AST System. Continuous collection of light refraction patterns generated growth curve that was used to determine whether the sample was likely positive or negative for bacteria. Further curve analysis ruled out mixed flora at lower concentrations, and “qualified” samples were identified directly on MALDI-TOF MS. AST for ampicillin, cefazolin, ceftriaxone and ciprofloxacin was performed concurrently on the instrument. Samples were incubated for up to 16 hours with results available as early as 2 hours.Results210 urine samples were tested. After 3 hours of incubation on the BacterioScan, 70 (33.3%) and 140 (67.7%) urine samples were reported as positive and negative for bacterial growth, respectively. 136/140 (97.1%) of the negative samples were either no growth (67.6%) or insignificant (32.4%) growth by culture. The remaining 4 (2.9%) were catheter (3) or surgical (1) samples that grew <10K CFU/mL uropathogens, which is below the assay’s LOD. 33/70 (47.1%) samples were tested on the 216R AST System; 37/70 (52.9%) samples omitted by curve analysis showed no or questionable significant growth by culture. Comparator data were available for 26/33 samples. Ampicillin and ceftriaxone demonstrated categorical agreement of 100%, while cefazolin and ciprofloxacin had 96% and 88% agreement, respectively, with 4% major errors for cefazolin and 12% minor errors for ciprofloxacin.ConclusionThe 216Dx UTI System could be utilized as a screening platform to rule out UTIs within 3 hours, with AST available after an additional 2–6 hours for suspect UTI positive samples. This could potentially prevent unnecessary antimicrobial therapy. Preliminary data are promising but testing of additional clinical samples is warranted.Disclosures A. Tomaras, BacterioScan, Inc: Employee, Salary Achaogen: Consultant, Consulting fee Forge Therapeutics: Consultant, Consulting fee Pfizer: Consultant, Consulting fee Spero Therapeutics: Consultant, Consulting fee