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Table 4 Identification by MALDI-TOF (direct and SepsiTyper (ST) methods) of Gram-positive cocci from positive blood cultures appearing monomicrobial at the Gram-stain, that resulted to be polymicrobial after subculture*

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 MALDI-TOF MS with score (S) of: No. of unidentified isolates Unidentified second species Total samples
S < 1.7 1.7 ≤ S < 2 2.0 ≥ S <2.3 S ≥ 2.3  
Direct ST Direct ST Direct ST Direct ST Direct ST
S. aureus    1      1    S. capitis  
S. epidermidis 1    1        E. faecalis  
S. capitis      1 1a      E. faecium  
S. capitis    1 1a        S. epidermidis  
S. hominis      1      1 S. haemolyticus  
S. hominis      1    1    S. epidermidis  
E. faecium     1    1     S. epidermidis  
Total (%) 1 (14 %)   2 (29 %) 3 (43 %) 3 (43 %) 1 (14 %) 1 (14 %) 2 (29 %)   1 (14 %)   7
  1. *Using the results obtained with the routine methods by MALDI-TOF and Vitek 2 as comparators
  2. aST correctly identified only the second species