Table 1: Antimicrobial resistance in Escherichia coli isolated from elderly patients with urinary tract infections.

ATM I (%) R (%) MIC Range (µg/mL) MIC50
(µg/mL)
MIC90
(µg/mL)
Ampicillin 0 80.5 ≤2-64 32 64
AMCa 3.1 28.6 ≤2-64 4.0 64
Cefazolin 46.2 21.6 ≤1-64 4.0 32
Cefuroxime 0 20.7 1-32 2.0 32
Cefoxitin 11.2 3.1 1-32 1.0 32
Cefotaxime 0 9.7 ≤1-64 0.25 2.0
Ceftazidime 0 9.7 ≤4-64 0.25 2.0
Cefepime 0 8.4 0.5-32 0.50 8.0
Ertapenem 0 0 ≤0.25-0.5 0.12 0.5
Imipenem 0 0 ≤0.25-1 0.12 0.50
Gentamicin 0.9 13.8 ≤0.5-128 0.50 64
Nalidixic acid 0.1 61.7 ≤16-64 32 64
Ciprofloxacin 3.0 42.8 ≤0.25-8 0.12 8.0
TMSb 0.1 37.6 2-320 2.0 160
Nitrofurantoin 0 2.3 2-128 4.0 32

ATM, antimicrobial; I, intermediate susceptibility; R, resistance; AMC, amoxicillin-clavulanate; TMS, trimethoprim-sulfamethoxazole. MIC, Minimum inhibitory concentration. aFor MICs determination, the concentration of clavulanic acid was fixed at 2 µg/mL. bTMS in the ratio 1:19. MICs values are expressed as the trimethoprim concentration.