Table 1.
Discrepancies and error in the conventional identification method (Vitek 2) and MALDI-TOF for the identification of 507 Gram-negative bacteria
| Final identification (no of isolates) | No of isolates | ||||||
|---|---|---|---|---|---|---|---|
| Conventional identification method (Vitek 2) | VITEK MS identification | Bruker MS identification | 16S rRNA sequence result (number of discrepant organisms sequenced) | ||||
| No ID | Mis-ID | No ID | Mis - ID | No ID | Mis-ID | ||
| Escherichia coli (181) | 0 | 0 | 0 | 0 | 0 | 0 | |
| Klebsiella pneumoniae (71) | 0 | 0 | 0 | 0 | 0 | 1 (score <1.7) | K. pneumoniae (1) |
| Klebsiella oxytoca (2) | 0 | 0 | 0 | 0 | 0 | 0 | |
| Pseudomonas aeruginosa (66) | 0 | 0 | 0 | 0 | 0 | 0 | |
| Acinetobacter baumannii (39) | 0 | 0 | 0 | 0 | 0 | 1 (Acinetobacter genomospecies 13TU)*, 3 (score <1.7) | A. baumannii (4) |
| Acinetobacter lwoffii (2) | 0 | 0 | 0 | 0 | 0 | 1 (score <1.7) | A. lwoffii (1) |
| Salmonella spp. (29) | 0 | 0 | 0 | 0 | 0 | 1 (score <1.7) | Salmonella spp. (1) |
| Enterobacter cloacae (14) | 0 | 0 | 0 | 0 | 0 | 0 | |
| Enterobacter aerogenes (7) | 0 | 0 | 0 | 0 | 0 | 0 | |
| Enterobacter asburiae (5) | 0 | 0 | 0 | 0 | 0 | 0 | |
| Pantoea agglomerans (1) | 0 | 0 | 0 | 0 | 0 | 0 | |
| Proteus mirabilis (17) | 0 | 0 | 0 | 0 | 0 | 0 | |
| Stenotrophomonas maltophilia (18) | 0 | 0 | 0 | 0 | 0 | 1 (score <1.7) | S. maltophilia (1) |
| Serratia marcescens (15) | 0 | 0 | 0 | 0 | 0 | 0 | |
| Citrobacter koseri (9) | 0 | 0 | 0 | 0 | 0 | 0 | |
| Citrobacter freundii (1) | 0 | 0 | 0 | 0 | 0 | 0 | |
| Morganella morganii (7) | 0 | 0 | 0 | 0 | 0 | 0 | |
| Achromobacter xylosoxidans (5) | 0 | 0 | 0 | 0 | 0 | 2 (Acinetobacter spp.) | A. xylosoxidans (2) |
| Providencia rettgeri (4) | 0 | 2 (Providencia stuartii) | 0 | 2 (P. stuartii) | 0 | 1 (score <1.7) | P. rettgeri (2) |
| Burkholderia cepacia (2) | 0 | 0 | 0 | 0 | 0 | 1 (score <1.7) | B. cepacia (1) |
| Sphingomonas paucimobilis (2) | 0 | 0 | 0 | 0 | 0 | 2 (score <1.7) | S. paucimobilis (2) |
| Aeromonas hydrophila/caviae (2) | 0 | 0 | 0 | 0 | 0 | 2 (Aeromonas jandaei) | A. hydrophila/caviae (2) |
| Ralstonia solanacearum (1) | 0 | 1(Ralstonia pickettii) | 0 | 1 (R. pickettii) | 0 | 1 (Ralstonia insidiosa) | R. solanacearum (1) |
| Chryseobacterium indologenes (1) | 0 | 0 | 0 | 0 | 0 | 0 | |
| Plesiomonas shigelloides (1) | 0 | 0 | 0 | 0 | 0 | 0 | |
| Vibrio parahaemolyticus (1) | 0 | 0 | 0 | 0 | 0 | 0 | |
| Campylobacter jejuni (1) | 0 | 0 | 0 | 0 | 0 | 0 | |
| Bordetella pertussis (1) | 0 | 0 | 0 | 0 | 0 | 0 | |
| Bordetella parapertussis (1) | 0 | 0 | 0 | 0 | 0 | 0 | |
| Yersinia enterocolitica (1) | 0 | 0 | 0 | 0 | 0 | 0 | |
No ID = no identification in spite of its presence in database; Mis-ID = misidentification; *Current name is Acinetobacter nosocomialis.