Table 3: Antibiotic resistance patterns of Gram-negative bacteria producing ESBLs and AmpC β-lactamases compared to nonproducer isolates.

AntibioticTotal number of Gram-negative rods (n = 311) valueTotal number of Gram-negative rods (n = 311) value
Non-ESBL (n = 227)ESBL (n = 84)AmpC (n = 101)Non-AmpC (n = 210)

Amikacin31 (36.9)61(26.9)0.08557 (56.4)35 (16.7)<0.001
Tobramycin50 (42)92 (40.5)0.13467 (66.3)67 (31.9)<0.001
Gentamicin40 (47.6)81 (35.7)0.05566 (65.3)55 (26.2)<0.001
Amoxicillin/clavulanate58 (69)91 (40.1)<0.00193 (92.1)56 (26.7)<0.001
Cefuroxime81 (96.4)137 (60.4)<0.00192 (91.1)126 (60)<0.001
Ceftazidime72 (85.7)76 (33.5)<0.00165 (64.4)83 (39.5)<0.001
Cefotaxime78 (92.9)85 (37.4)<0.00176 (75.2)87 (41.4)<0.001
Cefepime75 (89.3)87 (38.3)<0.00175 (74.3)87 (41.4)<0.001
Meropenem24 (28.6)59 (26.0)0.75550 (49.5)33 (15.7)<0.001
Piperacillin53 (63.1)77 (33.9)<0.00172 (71.3)58 (27.6)<0.001
Piperacillin/tazobactam42 (50)77 (33.9)0.01065 (64.4)54 (25.7)<0.001
Imipenem26 (31)62 (27.3)0.52758 (57.4)30 (14.3)<0.001
Aztreonam69 (82.1)98 (43.2)<0.00182 (81.2)85 (40.5)<0.001
Ciprofloxacin51 (60.7)92 (40.5)0.00274 (73.3)69 (32.9)<0.001
Ofloxacin50 (59.5)91 (40.1)0.00270 (69.3)71 (33.8)<0.001
Nitrofurantoin50 (59.5)103 (45.4)0.02778 (77.2)75 (35.7)<0.001
Trimethoprim/sulfamethoxazole76 (90.5)140 (61.7)<0.00191 (90.1)125 (59.5)<0.001
Colistin4 (4.8)5 (2.2)02327 (6.9)2(1.0)0.003