TABLE 1

In vitro activities of orally available antimicrobial agents against 868 urinary isolates of E. coli isolated by clinical laboratories across Canada from 2010 to 2013

E. coli isolate phenotype(s) (no. of isolates) and antimicrobial agentMIC50eMIC90MIC range% Susceptible% Intermediate% Resistant
All (868)
    Fosfomycin≤14≤1–51299.40.50.1
    SXT≤0.12>8≤0.12–>874.725.3
    Nitrofurantoin1632≤1–51296.12.41.5
    Ciprofloxacin≤0.06>16≤0.06–>1677.40.122.5
    Amoxicillin-clavulanate4160.5–>3281.313.05.7
Pansusceptible (481)a
    Fosfomycin≤12≤1–6410000
    SXT≤0.120.25≤0.12–21000
    Nitrofurantoin1632≤1–3210000
    Ciprofloxacin≤0.06≤0.06≤0.06–110000
    Amoxicillin-clavulanate480.5–810000
SXT susceptible (647)
    Fosfomycin≤14≤1–51299.50.30.2
    SXT≤0.120.25≤0.12–21000
    Nitrofurantoin1632≤1–51297.51.50.9
    Ciprofloxacin≤0.06>16≤0.06–>1686.2013.8
    Amoxicillin-clavulanate4160.5–>3286.18.55.4
SXT resistant (219)
    Fosfomycin24≤1–12899.10.90
    SXT>8>84–>80100
    Nitrofurantoin1632≤1–25691.85.03.2
    Ciprofloxacin1>16≤0.06–>1651.60.547.9
    Amoxicillin-clavulanate8161–>3267.126.56.4
Ciprofloxacin susceptible (672)
    Fosfomycin≤12≤1–51299.900.1
    SXT≤0.12>8≤0.12–>883.216.8
    Nitrofurantoin1632≤1–51297.51.80.7
    Ciprofloxacin≤0.06≤0.06≤0.06–110000
    Amoxicillin-clavulanate4160.5–>3285.78.95.4
Ciprofloxacin resistant (195)
    Fosfomycin24≤1–12897.92.10
    SXT>8>8≤0.12–>845.954.1
    Nitrofurantoin1632≤1–25691.34.64.1
    Ciprofloxacin>16>164–>1600100
    Amoxicillin-clavulanate8161–>3266.027.36.7
Amoxicillin-clavulanate susceptible (704)
    Fosfomycin≤12≤1–12899.60.40
    SXT≤0.12>8≤0.12–>879.120.9
    Nitrofurantoin1632≤1–25696.72.31.0
    Ciprofloxacin≤0.06>16≤0.06–>1681.70.118.2
    Amoxicillin-clavulanate480.5–810000
Amoxicillin-clavulanate resistant (49)
    Fosfomycin232≤1–51298.002.0
    SXT≤0.12>8≤0.12–>871.428.6
    Nitrofurantoin16328–51291.92.06.1
    Ciprofloxacin≤0.06>16≤0.06–>1673.5026.5
    Amoxicillin-clavulanate32>3232–>3200100
SXT and ciprofloxacin resistant (105)
    Fosfomycin24≤1–12898.11.90
    SXT>8>84–>80100
    Nitrofurantoin16644–25688.66.74.8
    Ciprofloxacin>16>164–>1600100
    Amoxicillin-clavulanate8162–>3256.235.28.6
ESBL producing (42)b
    Fosfomycin24≤1–410000
    SXT>8>8≤0.12–>835.764.3
    Nitrofurantoin1664≤1–25683.311.94.8
    Ciprofloxacin>16>16≤0.06–>169.5090.5
    Amoxicillin-clavulanate16321–3233.354.811.9
AmpC producing (16)c
    Fosfomycin24≤1–410000
    SXT≤0.12>8≤0.12–>875.025.0
    Nitrofurantoin16328–3210000
    Ciprofloxacin≤0.06>16≤0.06–>1675.0025.0
    Amoxicillin-clavulanate32>328–>326.36.387.4
MDR (15)d
    Fosfomycin24≤1–410000
    SXT>8>8≤0.12–>86.793.3
    Nitrofurantoin1612816–25660.0040.0
    Ciprofloxacin>16>168–>1600100
    Amoxicillin-clavulanate32>328–>3213.320.066.7
  • a Pansusceptible is defined as susceptible to SXT, nitrofurantoin, ciprofloxacin, and amoxicillin-clavulanate.

  • b The ESBL positivity rate of E. coli was 4.8% (42/868).

  • c The AmpC positivity rate of E. coli was 1.8% (16/868).

  • d MDR isolates were defined as those that were resistant to three or more agents in different antimicrobial classes (SXT, nitrofurantoin, ciprofloxacin, and amoxicillin-clavulanate).

  • e MIC50, concentration inhibiting 50% of the isolates; MIC90, concentration inhibiting 90% of the isolates. MICs are reported in μg/ml.