Table 2 Diagnostic accuracy of disk diffusion and MBT-ASTRA for tetracycline susceptibility testing in 100 clinical P. multocida isolates from cattle compared to the MIC-gradient strip test.

From: Rapid detection of tetracycline resistance in bovine Pasteurella multocida isolates by MALDI Biotyper antibiotic susceptibility test rapid assay (MBT-ASTRA)

 

Disk diffusion

MBT-ASTRA

Essential agreement

95%

98%

Very major error

3%

2%

Major error

2%

0%

Minor error

0%

0%

Sensitivity

93.5%

95.7%

(86.3%, 100.6%)

(89.8%, 101.5%)

Specificity

96.3%

100%

(91.3%, 101.3%)

(100.0%, 100.0%)

RPV

95.6%

100%

(89.5%, 101.6%)

(100.0%, 100.0%)

SPV

94.5%

96.4%

(88.5%, 100.5%)

(91.6%, 101.3%)

  1. Values between brackets represent the 95% confidence interval of the estimate. Definitions describing the diagnostic accuracy31,47,48.
  2. Essential agreement: results of both techniques identical; very major: resistant strain by the MIC-gradient strip test method misinterpreted as susceptible by disk diffusion/MBT-ASTRA; major: susceptible strain by the MIC-gradient strip test method misinterpreted as resistant by disk diffusion/MBT-ASTRA; minor error: intermediate result was obtained by only one method; sensitivity is number of resistant strains by disk diffusion or MBT-ASTRA/number of resistant strains by MIC-gradient strip test; specificity is number of susceptible strains by disk diffusion or MBT-ASTRA/number of susceptible strains by MIC-gradient strip test. RPV, resistant (positive) predictive value; the probability that a strain is truly resistant if the disk diffusion method or MBT-ASTRA categorizes a strain as resistant; SPV, susceptible (negative) predictive value is defined as the probability that a strain is truly susceptible if the disk diffusion method or MBT-ASTRA categorizes a strain as susceptible.
Back to article page