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Table 5 Likelihood of identifying resistance in isolates of NTSEC or M Haemolytica when tested using disk diffusion versus broth microdilution

From: Methodological comparisons for antimicrobial resistance surveillance in feedlot cattle

Resistance outcome Susceptibility testing method NTSEC (n=3362) M. haemolytica(n=1574)
OR1 95% CI2 P-value OR1 95% CI2 P-value
Ampicillin DD3 6.3 2.9 – 14.3 <0.0001 20.0 5.0 – 100 <0.0001
  BM4 ref    ref   
Amoxicillin-Clavulanate DD 5 10.0 3.0 – 33.3 0.0001
  BM     ref   
Ceftiofur DD 5.6 1.2 – 25.0 0.03 5
  BM ref      
Streptomycin DD 2.0 1.6 – 2.7 <0.0001 5
  BM ref      
Sulfisoxazole DD 1.3 0.9 – 1.9 0.11 5
  BM ref      
Tetracycline DD 0.6 0.5 – 0.8 0.0003 25.0 7.7 – 100 <0.0001
  BM ref    ref   
TMS6 DD 4.8 2.0 – 11.1 0.0004 5
  BM ref      
  1. 1Odds ratio comparing disk diffusion to broth microdilution as the reference category.
  2. 295% confidence intervals determined using Wald statistics.
  3. 3Disk Diffusion.
  4. 4Broth Microdilution.
  5. 5Model was not stable because of low resistance prevalence.
  6. 6Trimethoprim-Sulfamethoxazole.
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