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Table 1 Identification of Gram-negative bacilli from monomicrobial positive blood cultures by MALDI-TOF (direct method)*

From: Rapid and reliable identification of Gram-negative bacteria and Gram-positive cocci by deposition of bacteria harvested from blood cultures onto the MALDI-TOF plate

  No. of isolates   
Species Identification by use of direct method MALDI-TOF MS with score (S) of: No. of unidentified isolates Total (%)
S < 1.7 1.7 ≤ S < 2 2.0 ≥ S <2.3 S ≥ 2.3 Direct MALDI-TOF MS Routine MALDI-TOF MS
Klebsiella pneumoniae    4 40    44 (37.3 %)
Escherichia coli     23    23 (19.5 %)
Enterobacter aerogenes    1 4    5 (4.3 %)
Enterobacter cloacae    1 4    5 (4.3 %)
Enterobacter cancerogenus     1    1 (0.8 %)
Klebsiella oxytoca     3    3 (2.6 %)
Proteus mirabilis     3    3 (2.6 %)
Serratia marcescens    1 1    2 (1.7 %)
Citrobacter freundii     1    1 (0.8 %)
Pseudomonas aeruginosa   3 1 9    13 (11 %)
Acinetobacter baumannii    10 2    12 (10.2 %)
Acinetobacter lwoffii    1 1    2 (1.7 %)
Pseudomonas stutzeri    1     1 (0.8 %)
Stenotrophomonas maltophilia      1 1 1 (0.8 %)
Bacteroides fragilis     1    1 (0.8 %)
Fusobacterium nucleatum 1       1 (0.8 %)
Total (%) 1 (0.8 %) 3 (2.5 %) 20 (17 %) 93 (78.9 %) 1 (0.8 %)   118
  1. *Using the results obtained with the routine methods by MALDI-TOF and Vitek 2 as comparators
  2. No isolates were misidentified. No isolates were unidentified by Vitek 2