Table 2.
Identification by MALDI-TOF (direct method) of Gram-negative bacilli from positive blood cultures appearing monomicrobial at the Gram-stain, that resulted to be polymicrobial after subculture*
| Species | Identification by use of direct method MALDI- TOF MS | Total samples | |||
|---|---|---|---|---|---|
| Correct, with score (S) of: | Unidentified species | ||||
| 1.7 ≤ S < 2 | 2.0 ≥ S < .3 | S ≥ 2.3 | |||
| Klebsiella pneumoniae | 1 | Escherichia coli | 1 | ||
| Klebsiella pneumoniae | 1 | Proteus mirabilis | 1 | ||
| Klebsiella pneumoniae | 2 | Acinetobacter baumannii | 2 | ||
| Klebsiella pneumoniae | 1 | Acinetobacter calcoaceticus | 1 | ||
| Klebsiella pneumoniae | 1 | Serratia marcescens | 1 | ||
| Escherichia coli | 1 | Pseudomonas aeruginosa | 1 | ||
| Enterobacter aerogenes | 1 | Candida guillermondii | 1 | ||
| Pseudomonas aeruginosa | 1 | Klebsiella pneumoniae | 1 | ||
| Pseudomonas aeruginosa | 1 | Candida tropicalis | 1 | ||
| Acinetobacter baumannii | 1 | Klebsiella pneumoniae | 1 | ||
| Acinetobacter baumannii | 1 | Staphylococcus epidermidis | 1 | ||
| Stenotrophomonas maltophilia | 1 | Candida glabrata | 1 | ||
| No identification | Lactobacillus paracasei and Candida krusei | 1 | |||
| No identification | Serratia marcescens and Klebsiella oxytoca | 1 | |||
| Total (%) | 2 (13.3) | 8 (53.3) | 3 (20 %) | 15 | |
*Using the results obtained with the routine methods by MALDI-TOF and Vitek 2 as comparators. No isolates were misidentified. No isolates were identified with scores ≤ 1.7