Table 1.
Results of the Carba NP test
| Species (n)a | Carbapenemase detected (n)a | MIC(s) (μg/ml) |
Test resultb | ||
|---|---|---|---|---|---|
| Imipenem | Meropenem | Ertapenem | |||
| Non-carbapenemase producersc | |||||
| Citrobacter freundii (3) | None | 2–3 | 0.5–3 | 1.5–12 | − |
| Enterobacter aerogenes (4) | None | 0.5–4 | 0.06–1.5 | 0.12–16 | − |
| Enterobacter cloacae (28) | None | 0.19–6 | 0.06 to ≥32 | 0.25 | − |
| Escherichia coli (20) | None | 0.023–3 | 0.023–12 | 0.008 to ≥32 | − |
| Klebsiella oxytoca (1) | None | 0.25 | 0.25 | 1 | − |
| Klebsiella pneumoniae (18) | None | 0.19–4 | 0.016–12 | 0.016 to ≥32 | − |
| Morganella morganii (1) | None | 2 | 0.12 | 0.25 | − |
| Providencia stuartii (1) | None | 1.5 | 0.12 | 0.5 | − |
| Pantoea spp. (1) | None | 0.38 | 0.047 | 0.19 | − |
| Serratia fonticola (1) | None | 0.38 | 4 | − | |
| Serratia marcescens (6) | None | 0.38–4 | 0.023–0.5 | 0.25–2 | − |
| Pseudomonas aeruginosa (15)d | None | 6 to ≥32 | 3 to ≥32 | ND | − |
| Carba NP test-positive carbapenemase producerse | |||||
| Citrobacter freundii (3) | KPC (2) | 6–12 | 2–6 | 6–4 | + |
| NDM (1) | 4 | 1.5 | 6 | + | |
| Citrobacter youngae (1) | KPC | 16 | 6 | ≥32 | + |
| Enterobacter cloacae (25) | KPC (11) | 0.75 to ≥32 | 0.38 to ≥32 | 0.75 to ≥32 | + |
| NDM (4) | 2 to ≥32 | 0.75 to ≥32 | 2 to ≥32 | + | |
| NMC/IMI (6) | ≥32 | 6 to ≥32 | 16 to ≥32 | + | |
| VIM (4) | 6–24 | 6–32 | 2–24 | + | |
| Escherichia coli (33) | KPC (5) | 1–16 | 0.25 to ≥32 | 0.5 to ≥32 | + |
| NDM (10) | 4 to ≥32 | 2 to ≥32 | 12 to ≥32 | + | |
| OXA-48 (14) | 0.5–8 | 0.25–2 | 0.5 to ≥32 | + | |
| VIM (3) | 2–12 | 0.5–24 | 0.125–16 | + | |
| IMP-27 (1) | 0.5 | 4 | 3 | + | |
| Klebsiella oxytoca (3) | KPC (2) | 8–32 | 3–16 | 8–16 | + |
| OXA-48 (1) | 3 | 0.75 | 3 | + | |
| Klebsiella pneumoniae (28) | KPC (7) | 8 to ≥32 | 2 to ≥32 | 3 to ≥32 | + |
| NDM (13) | 3 to ≥32 | 2 to ≥32 | 4 to ≥32 | + | |
| OXA-48 (5) | 0.75–24 | 0.38–8 | 1 to ≥32 | + | |
| OXA-181 (3) | 12 to ≥32 | ≥32 | ≥32 | + | |
| Morganella morganii (3) | NDM | 8 to ≥32 | 0.38 to ≥32 | 0.38–12 | + |
| Pseudomonas putida (1) | IMP and VIM | ≥32 | ≥32 | ≥32 | + |
| Pantoea spp. (1) | KPC | 12 | 8 | 24 | + |
| Raoultella planticola (1) | KPC | 2–16 | 0.75 to ≥32 | 0.75–16 | + |
| Raoultella terrigena (2) | KPC | 16 | ≥32 | 16 | + |
| Serratia marcescens (5) | SME (4) | ≥32 | 12 to ≥32 | 4 to ≥32 | + |
| KPC (1) | ≥32 | 24 | ≥32 | + | |
| Pseudomonas aeruginosa (11)d | IMP (5) | ≥32 | ≥32 | ≥32 | + |
| VIM (6) | ≥32 | ≥32 | ND | + | |
| Carba NP test-negative carbapenemase producersc | |||||
| Enterobacter cloacae (1)f | NMC-A | ≥32 | 3 | 4 | − |
| Escherichia coli (4) | GES-5 (1) | ≥32 | ≥32 | ≥32 | − |
| OXA-48 (3) | 1.5–3 | 0.38–1 | 1.5–4 | − | |
| Klebsiella pneumoniae (13)f | OXA-48 (10) | 0.25–12 | 0.094–32 | 0.25 to ≥32 | − |
| OXA-181 (3) | 1–32 | 0.38 to ≥32 | 3 to ≥32 | − | |
| Proteus mirabilis (1) | IMP-27 | 4 | 4 | 4 | − |
| Providencia rettgeri (1)f | NDM-1 | ≥32 | ≥32 | 16 | − |
| Providencia stuartii (1) | NDM-1 | ≥32 | ≥32 | ≥32 | − |
| Serratia marcescens (6) | GES-5 (2) | ≥32 | ≥32 | ≥32 | − |
| SME-1 (4) | ≥32 | ≥32 | ≥32 | − | |
| Pseudomonas aeruginosa (2)d | GES-5 | ≥32 | ≥32 | ND | − |
n, number of isolates tested.
Carba NP test results: −, negative (red); +, positive (yellow/orange). All the results shown in this table were obtained using 3 to 4 10-μl loopfuls resuspended in 200 μl of the lysis buffer. The same results were obtained using the original protocol (1 10-μl loopful resuspended in 100 μl of the lysis buffer), except for some OXA-48-producing isolates (n = 15) that were detected only by the modified protocol.
Negative by PCR analysis for blaKPC, blaNDM, blaOXA-48-like, blaVIM, blaIMP, and blaGES-type genes (6, 7).
CLSI guidelines do not recommend ertapenem testing for Pseudomonas.
Positive by PCR analysis for at least one of blaKPC, blaNDM, blaOXA-48-like, blaVIM, blaIMP, and blaGES-type genes.
Mucoid strains. Five out of 10 OXA-48-producing K. pneumoniae isolates were mucoid.