Abstract:

Objective To investigate the role of matrix-assisted laser desorption/ionization time of flight mass spectrometry （MALDI-TOF MS） in the detection of pathogenic bacteria causing urinary tract infection. Methods A total of 1 000 midstream urine samples were collected and inoculated on solid media. Single colonies were identified by MALDI-TOF MS and Vitek 2 Compact. Midstream urine samples were directly detected by MALDI-TOF MS after pretreatment. Results Among the 1 000 midstream urine samples,215 cases with colony count ≥10⁵ CFU/mL were detected by culture method,and the positive detection rate was 21.5%. Among them,there were 162 cases isolated with single bacterium and 53 cases with mixed bacteria. The consistency rate for the identification of 215 cases by MALDI-TOF MS and Vitek 2 Compact was 100 %. Gram-negative bacteria accounted for 76.3%. Gram-positive bacteria accounted for 23.7%. Totally,185 cases with colony count ≥10⁵ CFU/mL were detected by MALDI-TOF MS directly,and the positive detection rate was 18.5%. Among them,145 cases of single bacterium were isolated,and 40 cases of mixed bacteria were found. The direct detection method had no false positive case. The positive detection rate was lower than that of culture method,and the positive leakage rate reached 14.0 %（30/215）. Conclusions MALDI-TOF MS for the direct detection of pathogenic bacteria from infectious midstream urine samples has the advantages of short identification and diagnosis time, low cost and good applicability.

Key words: Matrix-assisted laser desorption/ionization time of flight mass spectrometry, Urinary tract infection, Pathogenic bacterium