TABLE 2.

Results of isoelectric focusing, β-lactamase characterization, susceptibility testing, and pulsed-field gel electrophoresis analysis

Isolate grouppI(s)β-Lactamase(s)aNo. of isolatesRange of MICs (μg/ml)bPFGE pattern(s) (no. of isolates)c
AMCFOXCAZCAZ + CLACTXCTX + CLAATMFEPIPM
1a9.0, 7.6CMY-2, NE-SHV764-128128-25664->25664->25616-6416-3216-320.13-0.50.25-1
9.0, 7.6, 5.4CMY-2, NE-SHV, TEM-12364-128 (64/128)128->256 (128/>256)64->256 (128/>256)64->256 (128/>256)16-64 (32/64)8-32 (16/32)16-64 (16/32)0.13-0.5 (0.25/0.5)0.25-8 (0.5/1)
1b7.8, 7.6, 5.4DHA-1, NE-SHV, TEM-11264-128 (64/128)128->256 (256/>256)16-32 (16/32)64-256 (64/256)2-16 (4/16)4-64 (16/64)2-16 (4/16)0.06-0.25 (0.13/0.25)0.5-1 (0.5/1)Ia (3), XI (1), XIII (1), XV (1), XV (1), XVI (1), XVIII (1)
2a8.4, 7.8, 7.6, 5.4CTX-M-3, DHA-1, NE-SHV, TEM-1964-128≥1283264-12832-642-1616-648-320.5-2Ic (1), II (1), III (1), VIII (1), XVII (1)
7.9, 7.8, 7.6, 5.4CTX-M-14, DHA-1, NE-SHV, TEM-1164>25616321281616322VI (1)
2b8.4, 8.2, 7.8, 7.6, 5.4CTX-M-3, E-SHV, DHA-1, NE-SHV, TEM-1564-128≥256≥25664-12832-1284-16≥2568-160.5-2Id (1), X (1), XIV (1)
8.2, 7.9, 7.8, 7.6, 5.4E-SHV, CTX-M-14, DHA-1, NE-SHV, TEM-1164256>2561281288>256641
2c8.2, 7.8, 7.6, 5.4E-SHV, DHA-1, NE-SHV, TEM-1864-128≥128≥12864-1288-324-16≥1282-80.5-2Ib (2), IV (1), V (1), VII (1), IX (1), XII (1)
8.4, 8.25, 7.6, 5.4CTX-M-3, CMY-8, NE-SHV, TEM-1916-32>25616-648-3264-25616-648-642-160.25-1
9.0, 8.4, 7.6, 5.4CMY-2, CTX-M-3, NE-SHV, TEM-1164>25625612825612825642
9.0, 8.4, 8.2, 7.6, 5.4CMY-2, CTX-M-3, E-SHV, NE-SHV, TEM-11128>256>256128>256128642564
38.2, 7.6, 5.4IMP-8, NE-SHV, TEM-1164>256>25625632326481
8.2, 7.6, 5.4IMP-8, E-SHV, NE-SHV, TEM-1164>256>25625632320.2542
48.2, 7.6, 5.4E-SHV, NE-SHV, TEM-138-1632-64≥2568-1664-25616-32≥2568-160.5-1
8.2, 7.6E-SHV, NE-SHV216, 3232, 64>25616128, 2568>2568, 161
7.9, 7.6, 5.4CTX-M-14, NE-SHV, TEM-11643216812883281
7.9, 7.6CTX-M-14, NE-SHV2643216, 328, 16642, 48, 164, 80.5, 1
7.6E-SHV13232641612886421
57.6, 5.4NE-SHV, TEM-1716-6432-642-161-162-161-84-160.03-0.130.06-0.5
7.6NE-SHV416-6432-641-160.5-162-162-162-160.03-0.130.06-0.5
  • a E-SHV, SHV-type ESBL; NE-SHV, SHV-type non-ESBL.

  • b AMC, amoxicillin and clavulanic acid; FOX, cefoxitin; CAZ, ceftazidime; CAZ + CLA, ceftazidime and clavulanic acid (2 μg/ml); CTX, cefotaxime; CTX + CLA, cefotaxime and clavulanic acid (2 μg/ml); ATM, aztreonam; FEP, cefepime; IPM, imipenem. The MIC values at which 50% of the isolates tested were inhibited (MIC50) and MIC90 values are shown in parentheses (MIC50/MIC90).

  • c Only 24 randomly selected DHA-1-producing isolates were investigated. PFGE, pulsed-field gel electrophoresis.