TABLE 4.
Species | Enzyme (no. of isolates) | MIC (μg/ml)a
|
Inhibitory zone diam (mm)a,b
|
|||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
CTX
|
CAZ
|
CTX
|
CAZ
|
ATM
|
FEP range | |||||||||
Range | Median | MIC90 | Range | Median | MIC90 | Range | % Idd | Range | % Id | Range | % Id | |||
E. coli | CTX-M-1 (35) | 32->256 | 64 | > 256 | 2-8 | 2 | 4 | 6-14 | 100 | 16-24 | 82 | 10-18 | 100 | 14-22 |
CTX-M-15 (64) | 64->256 | 256 | > 256 | 4->256 | 32 | 128 | 6-14 | 100 | 6-20 | 100 | 6-18 | 100 | 10-22 | |
CTX-M-32 (4) | 128->256 | 256 | 16-48 | 32 | 6-10 | 100 | 14-16 | 100 | 6-12 | 100 | 16 | |||
K. pneumoniae | CTX-M-1 (3) | 24->256 | 32-64 | 6-10 | 100 | 14-20 | 100 | 6-14 | 100 | 10-18 | ||||
CTX-M-15 (5) | 64->256 | 128 | 24-64 | 32 | 6-10 | 100 | 10-14 | 100 | 6-10 | 100 | 10-20 | |||
CTX-M-32 (2) | >256 | >256 | 6 | 100 | 6 | 100 | 6 | 100 | 14-16 |
CTX, cefotaxime; CAZ, ceftaxidime.
ATM, aztreonam; FEP, cefepime.
A 6-mm value means no zone of inhibition. The breakpoints for suspicion of ESBL production were as follows: CTX, ≤27 mm; CAZ, ≤22 mm; ATM, ≤27 mm (10).
% Id, percentage of isolates categorized as putative ESBL producers by disk diffusion testing, based on the CLSI breakpoint for suspicion of ESBL production, with the corresponding drug (10).