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Table 2 Comparison of phenotypic and genotypic analysis methods for the detection of carbapenem-resistance determinants in a panel of 108 carbepenem non-susceptible Enterobacteriaceae

From: Comparison of phenotypic methods for the detection of carbapenem non-susceptible Enterobacteriaceae

  

MHT

Etest MBL

EDTA DDST

RDCK™

Molecular tests

RD

N.

ID

ND

ID

ND

ID

ND

ID

ND

ID

ND

KPC-2/3

87

87

0

0

87

0

87

87

0

87

0

VIM-1/2

5

4

1

5

0

5

0

3

2

5

0

KPC-2 plus VIM-1

3

2

1

0

3

0

3

0

3*

3

0

NDM-1

1

0

1

1

 

1

0

1

0

1

0

OXA-48

5

2

3

0

5

0

5

5

0

5

0

Total

101

95/101

 

6/11

 

6/11

 

96/101

 

101/101

 

Technique sensitivity/specificity

 

Sensitivity 94%

Sensitivity 54.5%

Sensitivity 54.5%

Sensitivity 95%

Sensitivity 100%

Specificity 100%

Specificity 100%

Specificity 100%

Specificity 99%

Specificity 100%

  1. MTH: Modified Hodge Test; DDST: Double Disk Synergy Test; RDCK ™: Rosco Diagnostics Confirmation Kit; RD: resistance determinants; N.: number of isolates; ID: identified; ND: not detected; *in one case the isolate harboring KPC and VIM was misclassified as OXA-48 producer, in two other cases the results were doubtful.
  2. AmpC- and ESBL-positive strains were not detected by MHT, Etest MBL and EDTA DDST while molecular tests correctly identified both AmpC and ESBL determinants.
  3. RDCK™ did not indicated the presence of ESBL determinants as indicated by manufacturer’s instructions and misclassified as OXA-48 producer 2 out of 4 AmpC producers.