MP24-03 DIRECT DETECTION OF URINARY TRACT INFECTION FROM URINE SAMPLES USING MATRIX-ASSISTED LASER DESORPTION IONIZATION-TIME OF FLIGHT MASS SPECTROMETRY

Abstract

INTRODUCTION AND OBJECTIVES: Traditionally, the microbiological confirmation of urinary tract infection (UTI) takes 2-3 days. Before the results are available, clinicians initiate treatment with antibiotics. These antibiotics are in many cases unnecessary, inefficient or cover a wider spectrum of microorganism than necessary and as results, the antibiotics resistance bacteria may be possible to produce. Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry (MALDI-TOF MS) becomes a rapid tool of the identification of bacteria and yeast. Thus, we collected urine specimens and compared between the results of conventional confirmation and these of directly identification by MALDI-TOF MS. METHODS: Urine samples were gathered from patients with UTI symptoms processed by conventional culture between January and September 2015 in Kobe University Hospital. These specimens grow in culture and analyzed the conventional confirmation and MALDI-TOF MS identification by Vitek MS system (bioM erieux). According to the manufacture, a score 2.0 indicated species identification, a score between 1.7 to 2.0 indicated genus identification and a score of < 1.7 indicates no identification. RESULTS: We tested these specimens [gram positive rods (GPR): 3.48 %, gram positive cocci (GPC): 33.7 %, gram negative rods (GNR): 59.3 % and Candida species: 3.52 %] isolated by conventional confirmation. The bacteria isolated directly by MALDI-TOF MS ( 2.0) were 66.7 % of GPR, 24.1% of GPC, 70.6% of GNR and no Candida species, and the bacteria ( 1.7) were 66.7 % of GPR, 44.8 % of GPC, 88.2 % of GNR and none of Candida species from urine samples. The most relevant bacteria was Escherichia coli (34.9 %), followed by Staphylococcus aureus (8.14 %) and Staphylococcus epidermidis (8.14 %). CONCLUSIONS: MALDI-TOF MS showed high rate of accuracy about 90% for the identification of GNR, but not GPR, GPC and Yeast. This strategy could become a rapid (15 minutes per sample) and accurate diagnostic method of especially in GNR-causing UTI so far and further improvement is necessary for application to GPR, GPC and Yeast by for instance revised condition setting. This may accomplish a strong possibility to improve the adequacy of UTI treatment in terms of reducing the time of empiric antibiotic treatment or allowing for the earlier withdrawal of unnecessary antibiotics.