TABLE 1.
MICs of imipenem, meropenem, and ceftazidime for 29 clinical A. baumannii isolates, identification of β-lactamase genes and upstream IS elements by PCR, and LC-MS/MS detection of β-lactamase proteins
| Isolate no. | MIC (mg/liter)a |
blaOXA-51-like/OXA-51-like |
blaOXA-23-like/OXA-23-like |
blaOXA-40-like/OXA-40-like |
blaADC-like/ADC-like |
Other β-lactamases |
PFGE type | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| IPM | MEM | CAZ | PCR | IS | LC-MS/MS | PCR | IS | LC-MS/MS | PCR | IS | LC-MS/MS | PCR | IS | LC-MS/MS | PCR | IS | LC-MS/MS | ||
| 1 | 4 | 8 | 64 | + | − | − | − | − | − | − | + | ISAba1 | + | 10 | |||||
| 2 | 4 | 4 | 64 | + | − | − | − | − | − | − | + | ISAba1 | + | 10 | |||||
| 3 | 2 | 1 | 64 | + | − | − | − | − | − | − | + | ISAba1 | + | 3 | |||||
| 4 | 4 | 8 | 64 | + | − | − | − | − | − | − | + | ISAba1 | + | 7 | |||||
| 5 | 8 | 4 | 64 | + | − | − | − | − | − | − | + | − | − | blaCMY-2-like | − | CMY-2-like | 6 | ||
| 6 | 4 | 4 | 64 | + | ISAba1 | + | − | − | − | − | + | ISAba1 | + | 7 | |||||
| 7 | 4 | 4 | 64 | + | − | − | − | − | − | − | + | ISAba1 | + | 13 | |||||
| 8 | 4 | 2 | 64 | + | − | − | − | − | − | − | + | ISAba1 | + | 12 | |||||
| 9 | 4 | 4 | 64 | + | − | − | − | − | − | − | + | ISAba1 | + | 10 | |||||
| 10 | 4 | 1 | 64 | + | − | − | − | − | − | − | + | − | − | blaPER-1-like | ISPa12b | PER-1-like | 8 | ||
| 11 | 4 | 4 | 8 | + | − | − | − | − | − | − | + | − | − | 14 | |||||
| 12 | 2 | 0,5 | 8 | + | − | − | − | − | − | − | + | − | − | 2 | |||||
| 13 | 4 | 4 | 8 | + | − | − | − | − | − | − | + | − | − | 9 | |||||
| 14 | 32 | 16 | 64 | + | − | − | − | − | + | − | + | + | ISAba1 | + | 1 | ||||
| 15 | 32 | 16 | 64 | + | − | − | − | − | + | − | + | + | ISAba1 | + | 1 | ||||
| 16 | 32 | 16 | 64 | + | − | − | − | − | + | − | + | + | ISAba1 | + | 1 | ||||
| 17 | 32 | 16 | 64 | + | − | − | − | − | + | − | + | + | ISAba1 | + | 1 | ||||
| 18 | 32 | 16 | 16 | + | ISAba16 | − | + | ISAba1 | + | − | − | + | ISAba1 | + | 12 | ||||
| 19 | 32 | 16 | 32 | + | ISAba16 | − | + | ISAba1 | + | − | − | + | ISAba1 | + | 12 | ||||
| 20 | 32 | 16 | 64 | + | − | − | + | ISAba1 | + | − | − | + | ISAba1 | + | blaPER-1-like | ISPa12 | PER-1-like | 15 | |
| 21 | 32 | 16 | 32 | + | − | − | + | ISAba1 | + | − | − | + | ISAba1 | + | 12 | ||||
| 22 | 32 | 16 | 64 | + | − | − | + | ISAba1 | + | − | − | + | ISAba1 | + | blaPER-1-like | ISPa12 | PER-1-like | 15 | |
| 23 | 32 | 16 | 32 | + | ISAba16 | − | + | ISAba1 | + | − | − | + | ISAba1 | + | 12 | ||||
| 24 | 32 | 16 | 64 | + | − | − | + | ISAba1 | + | − | − | + | ISAba1 | + | 5 | ||||
| 25 | 32 | 16 | 64 | + | − | − | + | ISAba1 | + | − | − | + | ISAba1 | + | 5 | ||||
| 26 | 32 | 16 | 64 | + | − | − | + | ISAba1 | + | − | − | + | ISAba1 | + | 5 | ||||
| 27 | 4 | 4 | 64 | + | − | − | − | − | − | − | + | ISAba1 | + | 7 | |||||
| 28 | 32 | 16 | 32 | + | ISAba16 | − | + | ISAba1 | + | − | − | + | ISAba1 | + | 12 | ||||
| 29 | 32 | 16 | 64 | + | − | − | + | ISAba1 | + | − | − | + | − | − | blaGES-1-like | − | GES-1-like | 4 | |
a
CLSI breakpoints for imipenem and meropenem were as follows: susceptible, ≤4 mg/liter; intermediate, 8 mg/liter; resistant, ≥16 mg/liter. Breakpoints for ceftazidime were as follows: susceptible, ≤8 mg/liter; intermediate, 16 mg/liter; resistant, ≥32 mg/liter (12). IPM, imipenem; MEM, meropenem; CAZ, ceftazidime.
b
Isolate 10 contained an additional 44-bp fragment between the left inverted repeat of ISPa12 and the start codon of blaPER-1, compared to isolates 20 and 22 (18).