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Table 2 Sensitivity (Se, %), specificity (Sp, %), positive and negative likelihood ratios (LR+ and LR-, respectively) of screening strategies for carbapenemase-positive isolates among 349 isolates non-susceptible to ertapenem

From: Development of an algorithm for phenotypic screening of carbapenemase-producing Enterobacteriaceae in the routine laboratory

Antibiotic and diameter (< in mm)

Number (%) of isolates

Se

%

Sp

%

LR+

LR-

Carbase+

(n = 52)

Carbase-

(n = 297)

Clinical breakpoints

 IMI 24

22 (42.3)

44 (14.8)

42.3

85.2

2.84

0.68

 MER 22

22 (42.3)

40 (13.5)

42.3

86.5

3.12

0.67

 DOR 24

17 (32.7)

22 (7.4)

32.7

92.6

4.37

0.72

 TAZ 21

51 (98.1)

220 (74.1)

98.1

25.9

1.31

0.11

 TCC 24

51 (98.1)

292 (98.3)

98.1

1.7

0.99

1.53

 FEP 24

42 (80.8)

138 (46.5)

80.8

53.5

1.73

0.37

Cut-offs

 MER 27 a

40 (76.9)

80 (27.0)

76.9

73.0

2.83

0.32

 TEM 8 a

35 (67.3)

12 (4.0)

67.3

96.0

15.97

0.34

 TAZ 16 b

46 (88.5)

105 (35.4)

88.5

64.7

2.48

0.19

 TEM 12 b

43 (82.7)

65 (21.9)

82.7

78.1

3.73

0.23

 MER 25 c

32 (61.5)

59 (19.9)

61.5

80.1

3.07

0.48

 TCC 15 d

51 (98.1)

227 (76.4)

98.1

23.6

1.27

0.12

 TEM 15 d

50 (96.2)

126 (42.4)

96.2

57.6

2.24

0.08

 FEP 26 d

43 (82.7)

162 (54.6)

82.7

45.4

1.51

0.39

Combination of cut-offs

 TAZ 16 & TEM 12 b*

39 (75.0)

48 (16.2)

75.0

58.9

4.62

0.08

 TCC 15 & TEM 15 d

50 (96.2)

94 (31.7)

96.2

68.3

3.00

0.07

 TCC 15 & TEM 15 & IMI 22 d

52 (100)

109 (36.7)

100

63.3

2.70

0.01

 TCC 15 & TEM 15 & MER 22 d

52 (100)

110 (37.0)

100

63.0

2.67

0.01

 TCC 15 & TEM 15 & IMI 22 & FEP 26 d

52 (100)

92 (31.0)

100

69.0

3.19

0.01

 TCC 15 & TEM 15 & MER 22 & FEP 26 d

52 (100)

93 (31.3)

100

68.7

3.16

0.01

Combination of cut-offs + additional tests

 TCC 15 & TEM 15 & IMI 22 & IMI 32-Clo d,e

51 (98.1)

81 (27.3)

98.1

72.7

3.55

0.04

 TCC 15 & TEM 15 & MER 22 & MER 32-Clo d,e

52 (100)

68 (22.9)

100

77.1

4.31

0.01

 TCC 15 & TEM 15 & IMI 22 & FEP 26 d & IMI 32-Clo d,e

51 (98.1)

71 (23.9)

98.1

76.1

4.05

0.04

 TCC 15 & TEM 15 & MER 22 & FEP 26d & MER 32-Clod,e

52 (100)

63 (21.2)

100

78.8

4.65

0.01

 MER 25 & TEM 11 & Rosco confirm kit c,f

29 (55.8)

23 (9.4)

55.8

90.6

5.82

0.49

 MER 27 & TEM 8 & Rosco confirm kit a,g

36 (69.2)

14 (4.7)

69.2

95.3

14.15

0.33

  1. IMI imipenem, MER meropenem, DOR doripenem, FEP cefepime, TAZ piperacillin/tazobactam, TCC ticarcillin/clavulanate, TEM temocillin, Carbase+ or Carbase- carbapenemase-positive or -negative isolate
  2. areference [13]; b*85 (24.4%) isolates not classified according to reference [14] strategy; creference [15]; dthis study
  3. ecloxacillin test applied only to chromosomally encoding AmpC Enterobacteriaceae
  4. f258 (73.9) of our isolates not tested according to reference [15] because of meropenem diameter ≥25 mm towards these isolates
  5. g 229 (65.6%) of our isolates not tested according to reference [13] because of meropenem diameter ≥27 mm towards these isolates
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BMC Infectious Diseases

ISSN: 1471-2334

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