Table 1. Characterization of the 149 bacterial strains analyzed and data summary of imipenem hydrolysis assay utilizing MALDI-TOF MS.
| MALDI-TOF analysis | ||||
| Strain type: No. of isolates | ||||
| (Location of isolates [No.of isolates]) | Range of the ratio of the area of imipenem/metabolite based on the time of incubation | No. of isolates detected as carbapenemase producers (disappearance of the peak at 300 m/z or ratio between the peak for imipenem and its metabolite being <0.5) based on the time of incubation | ||
| 2 h | 4 h | 2 h | 4 h | |
| Carbapenem-resistant strains (70) (imipenem MIC >8 mg/L) | 67 | 70 | ||
| K. pneumoniae KPC: 1 | <0.01 | <0.01 | 1 | 1 |
| K. pneumoniae NDM-1: 2 | <0.01 | <0.01 | 2 | 2 |
| P. aeruginosa VIM: 2 | <0.01 | <0.01 | 2 | 2 |
| P. aeruginosa IMP: 2 | <0.01 | <0.01 | 2 | 2 |
| A.baumannii blaOXA23-like: 57 (Marseille [17], Algeria [40]) | <0.01–1.77 | <0.01–0.23 | 54 | 57 |
| A.baumannii blaOXA24-like: 3 (Algeria) | <0.01 | 0.02–0.04 | 3 | 3 |
| A.baumannii blaOXA23-like+blaOXA24-like: 3 (Algeria) | <0.01–0.48 | <0.01–0.06 | 3 | 3 |
| Carbapenem-susceptible strains (79) (imipenem MIC £2 mg/L) | 0 | 0 | ||
| K. pneumoniae ESBL: 31 (Algeria) | ND | 0.64–14.84 | 0 | 0 |
| K. pneumoniae non ESBL: 4 (Algeria) | ND | 1.24–5.82 | 0 | 0 |
| Escherichia coli ATCC 25922 (1) | 1.64 | 1.17 | 0 | 0 |
| A. baumannii: 43 (Marseille [1], Algeria [42]) | 0.61–12.86 | 0.97–4.96 | 0 | 0 |