The Significance Of UC-3500 And UF-5000 Urine Analytical System Combined With MALDI-TOF MS Technique In Urinary Tract Infection Diagnosis

Objective:To evaluate the significance of UC-3500 and UF-5000 urine analytical system combined with MALDI-TOF MS(Matrix-assisted laser desorption ionization time-of-flight mass spectrometry)technique in screening patients with urinary tract infection(UTI).Methods:During Jul to Sep 2018,1510 midstream urine samples were collected from patients with suspected UTI.The specimens were divided into two parts:one for urine culture;the other for the analysis of mass spectrometry,leukocyte lipase(LEU),nitrite(NIT),leukocyte count(WBC),bacterial counts(BACT),bacterial gram typing(BACT-Info)and yeast count(YLC)by MALDI-TOF MS and urine assembly line.Finally,the results of midstream urine culture was considered as the criterion.Meanwhile,the receiver operating characteristic curve(ROC curve)was used to determine the cut-off and accuracy of urine sediment WBC and BACT in the diagnosis of UTI,and the consistency between BACT-Info and culture results in UF-5000 system was assessed.In addition,urine specimens were enriched in bacteria after differential centrifugation.Subsequently,these microorganisms were directly identified by MALDI-TOF MS,which were compared with those of midstream urine culture.Results:Of 1510 specimens,488 pathogenic microorganisms were separated by culture.The coincidence rates of Gram-negative bacteria and Gram-positive bacteria identified by UF-5000 was 93.2%and 87.8%,and the total in bacteria was 75.4%.The coincidence rate of YLC was 84.93%.The optimal parameter was NIT+WBC+BACT in the diagnosis of UTI,and its accuracy was 89.74%.The cut-off value of urinary sediment WBC counts in the diagnosis of UTI was 63.85/μl,and BACT was 407.4/μl.Compared with culture,the accuracy rate of Escherichia coli directly identified by MALDI-TOF MS was up to 92.3%.Conclusions:The assembly line of UC-3500 and UF-5000 combined with MALDI-TOF MS direct identification technology displays a high coincidence rate in the diagnosis of UTI,which can provide a reliable basis for its early diagnosis and reasonable treatement.