Prospective Evaluation of Light Scatter Technology Paired with Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry for Rapid Diagnosis of Urinary Tract Infections

摘要

Urinary tract infections (UTI) are a leading cause of health care visits in the United States (1). Consequently, urine cultures are one of the most frequently ordered tests in clinical microbiology laboratories (2). Given that culture requires 18 to 24 h for pathogen growth and an additional 18 to 48 h for identification (ID) and antimicrobial susceptibility testing (AST) results, rapid alternatives are needed to streamline therapy. Screening tests, including point-of-care leukocyte esterase and nitrite detection, exist; however, these tests often produce false negatives, particularly in the setting of low-colony-count bacteriuria (3, 4). More accurate laboratory-based rapid alternatives, including flow cytometry (5, 6) and automated image analysis (7, 8), have been proposed but have not been widely adopted. Matrix-assisted laser desorption ionization–time of flight mass spectrometry (MALDI-TOF MS) has recently been applied as a direct urine-screening tool. Several studies have evaluated this approach using a variety of centrifugation and filtration techniques to separate bacteria from substances that might interfere with MALDI-TOF MS (i.e., white blood cells) (9–17). Unfortunately, these protocols have shown limited promise. The procedures are laborious, and more importantly, they lack sensitivity, with a maximum of 88% sensitivity reported (16), limiting application as a screening tool.