TABLE 1

Phenotypic and genotypic characteristics of aminoglycoside susceptibility and resistance among Klebsiella pneumoniae, Pseudomonas aeruginosa, and Acinetobacter baumannii isolates included in this study

IsolateaOriginbSusceptibility testingcAminoglycoside resistance gene(s)d
Zone of inhibition (mm)MIC (μg/ml)
AMKGENTOBARBAMKGENTOBARB
P. aeruginosa ATCC 2785322202427410.250.5ND
Escherichia coli ATCC 259222523222520.512ND
A. baumannii 360/10São Paulo, Brazil11668>128>128>128256aacA4, aacA1, aphA7
A. baumannii 874/13São Paulo, Brazil8669>128e>128>128128aacA4, aac(3)-I, aphA7
A. baumannii 143/14São Paulo, Brazil6667>128>128>128256aacA4, aacC1, aphA7, aadB, aadA1, aphA6
P. aeruginosa HC402/07São Paulo, Brazil66615>128>128>12832aacA4, aph(3)-IIb, aphA6, aadA6
P. aeruginosa HC408/07São Paulo, Brazil66622>128>128>1284aacA4, aph(3)-IIb, aphA6, aadB, aadA6
P. aeruginosa HC305/07São Paulo, Brazil66618>128>128>1288aacA4, aph(3)-IIb, aphA6, aadB, aadA6
P. aeruginosa 463/12São Paulo, Brazil126614>128>128>12832aacA4, aph(3)-IIb, aadB, aadA6, strA, strB
P. aeruginosa 1206/13São Paulo, Brazil66617>128>128>1288aacA4, aph(3)-IIb, aphA6, aadA2
P. aeruginosa 9me/14São Paulo, Brazil6666>128>128>128>256aacA4, aph(3)-IIb, aadA7, rmtD1
P. aeruginosa 862/07São Paulo, Brazil6666>128>128>128>256rmtD
P. aeruginosa HC367/07São Paulo, Brazil6666>128>128>128>256rmtD
P. aeruginosa HC103/07São Paulo, Brazil6667>128>128>128>256rmtD
P. aeruginosa HC84/07São Paulo, Brazil6666>128>128>128128rmtD
P. aeruginosa HC313/07São Paulo, Brazil6666>128>128>128>256rmtD
P. aeruginosa HC58/07São Paulo, Brazil6666>128>128>128>256rmtD
P. aeruginosa 883/07São Paulo, Brazil6666>128>128>128>256rmtD
P. aeruginosa 979/09São Paulo, Brazil6666>128>128>128>256rmtD
K. pneumoniae 931/08São Paulo, Brazil6666>256>256>256>256rmtGf
K. pneumoniae 1180/11São Paulo, Brazil6666>256>256>256>256rmtGf
P. aeruginosa 102United States26222625410.252aph(3)-IIb
P. aeruginosa 104United States26232726410.252aph(3)-IIb
P. aeruginosa 105United States30222525410.251aph(3)-IIb
P. aeruginosa 106United States21182222840.52aph(3)-IIb
A. baumannii 162United States2626252710.50.250.25
A. baumannii 165United States26272628110.250.25
A. baumannii 172United States25262527410.51
A. baumannii 176United States25232425210.52
  • a E. coli ATCC 25922 and P. aeruginosa ATCC 27853 were used as negative controls for all experiments. A. baumannii 360/10, 874/13, and 143/14 and P. aeruginosa HC402/07, HC408/07, HC305/07, 463/12, 1206/13, and 9me/14 were subjected to WGS.

  • b City and/or country of origin.

  • c A value of 6 indicates the absence of a zone of inhibition. The concentrations of amikacin (AMK), gentamicin (GEN), tobramycin (TOB), and arbekacin (ARB) disks were 30, 10, 10, and 10 μg, respectively. Arbekacin disks were purchased from Eiken Chemical (Tokyo, Japan) and provided by Meiji Seika Kaisha Ltd.

  • d Aminoglycoside resistance genes were identified by whole-genome sequencing; 16S-RMTase genes were also identified by PCR. Dashes indicate that no gene was detected. ND, not determined.

  • e Isolate that showed a 4-fold MIC reduction with amikacin in combination with PAβN in an efflux assay.

  • f These two isolates were not included for WGS, and the 16S-RMTases were detected by PCR.