Abstract
Urinary tract infections (UTIs) are very common and are becoming a concern in the medical community due to the growing prevalence of antimicrobial resistance in causative pathogens. The poor analytic performance or long time requirements of current diagnostic tests contribute to this problem, as antibiotic treatment often needs to be administered before the cause of the infection is confirmed, which frequently leads to prescription of antibiotics based solely on often inadequate preliminary clinical observations or test results. Matrix Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry (MALDI-TOF-MS) has been successfully used to identify cultured microorganisms, but protocols that employ MALDI to directly identify microorganisms in clinical samples are still under development. This study aims to develop a simple, fast, and cost-effective MALDI method that could potentially diagnose UTIs by accurately detecting Escherichia coli in clinical urine samples. The protocol was developed using cultured E. coli, which was smeared directly onto the MALDI plate then overlaid with α-Cyano-4-hydroxycinnamic acid (HCCA) matrix. The samples were identified using Bruker MALDI Biotyper software. Using this protocol, MALDI could reliably identify E. coli samples with high Bruker Biotyper quality values. Clinical urine samples were spotted directly onto the MALDI plate either without preparation or after a simple centrifugation, then overlaid and analyzed in the same way. MALDI was able to identify E. coli in some samples, but in many cases identification failed. Further work is required to determine the cause of the failures, and what can be done to improve the analysis quality to increase the likelihood of successful detection.