TABLE 1

Rapid aminoglycoside NP test results for AG-resistant enterobacterial producers of 16S rRNA methylases and AG-modifying enzymes and for AG-susceptible enterobacterial isolates

IsolateSpeciesMechanism of AG resistanceaResistance findings forb:Rapid aminoglycoside NP resultc
AmikacinGentamicin
MIC (μg/ml)PhenotypeMICPhenotype
AG susceptible
    FR136 Escherichia coli ATCC 25922 2S0.5S
    R2278 Escherichia coli ATCC 35218 4S1S
    R1436 Escherichia coli 2S1S
    R1438 Escherichia coli 2S1S
    R347 Klebsiella pneumoniae 4S0.5S
    S155 Klebsiella pneumoniae 2S0.5S
    R1433 Enterobacter cloacae 4S2S
    R713 Enterobacter cloacae 4S0.5S
    HM Enterobacter cloacae 4S2S
    R2260 Proteus mirabilis 4S4S
AG-resistant producers of methylases
    R989 Escherichia coli armA >256R>256R+
    R1012 Escherichia coli armA >256R>256R+
    R500 Klebsiella pneumoniae armA >256R>256R+
    R108 Klebsiella pneumoniae armA >256R>256R+
    R2257 Klebsiella pneumoniae armA >256R>256R+
    R2258 Enterobacter cloacae armA >256R>256R+
    62Carb Escherichia coli rmtB >256R>256R+
    E28 Escherichia coli rmtB >256R>256R+
    R107 Escherichia coli rmtB >256R>256R+
    R990 Escherichia coli rmtB >256R>256R+
    R262 Escherichia coli rmtC >256R>256R+
    R451 Escherichia coli rmtC >256R>256R+
    R265 Providencia stuartii rmtC >256R>256R+
    R38 Providencia stuartii rmtC >256R>256R+
    N34 Klebsiella pneumoniae rmtC >256R>256R+
    R502 Klebsiella pneumoniae rmtF >256R>256R+
    R2160 Klebsiella pneumoniae rmtG >256R>256R+
    R2161 Escherichia coli TOP10 npmA 128R32R+
AG-resistant producers of AG-modifying enzymes
    pWP701 Escherichia coli AAC(3)-IV1S128R
    pFCT4392 Escherichia coli AAC(3)-Ia1S32R
    390 Escherichia coli AAC(3)-IV16S>128R
    22089 Escherichia coli AAC(3)-I, AAC(3)-V16S128R
    97 Escherichia coli AAC(3)-IV2S32R
    92/31 Escherichia coli AAC(3)-IV4S16R
    4000 Escherichia coli APH(3′)-I, AAC(3)-V4S64R
    pFCT1163 Escherichia coli AAC(6′)-Ia>128R4S
    1054 Escherichia coli AAC(6′)-I8S8I
    1488 Escherichia coli AAC(6′)-II4S16R
    1054 Escherichia coli AAC(6′)-I16S8I
    RP4 Escherichia coli APH(3′)-Ib1S1S
    122971 Escherichia coli ANT(2″)4S>128R
    1800 Klebsiella pneumoniae AAC(6′)-I + AAC(3)-I32I16R
    13000 Klebsiella pneumoniae APH(3′)-I, AAC(3)-V0.5S>128R
    22233 Klebsiella pneumoniae AAC(3)-V16S>128R
    1110 Enterobacter cloacae ANT(2″)1S32R
    BM2667 Providencia stuartii APH(3′)-VI, AAC(2′)64R16R
    531 Providencia rettgeri AAC(2′)16S4S
    4290 Serratia marcescens AAC(3)-I4S64R
  • a AAC, N-acetyltransferases; ANT, O-adenyltransferases, APH, O-phosphotransferases.

  • b MICs were determined by broth microdilution method. S, susceptible; R, resistant; I, intermediate.

  • c Results of the rapid aminoglycoside NP test after 2 h of incubation at 35 ± 2°C under ambient air.