Table 5 The number of studies about bacterial identification method, phenotypic detection method, and break point reference guideline of gram-negative isolates in the present systematic review

 Morphology/Biochemical testing

30 (38.961%)

[24, 26, 31, 34, 35, 38, 41,42,43, 47, 49, 50, 53,54,55, 57, 60, 62, 63, 66, 67, 92,93,94,95,96,97,98, 100, 101]

 API

24 (31.168%)

[10, 13,14,15,16,17,18,19, 21, 22, 28, 32, 33, 36, 37, 51, 52, 56, 70,71,72,73, 90, 99]

 VITEK

4 (5.195%)

[6, 40, 64, 69]

 MALDI-TOF

1 (1.299%)

[59]

 PCR

8 (10.390%)

[23, 25, 44,45,46, 58, 68, 91]

 Not mentioned

10 (12.987%)

[9, 20, 27, 29, 30, 39, 48, 61, 65, 102]

 DDM*

63 (81.818%)

[10, 13, 14, 16,17,18,19,20, 22,23,24,25,26,27,28,29,30,31, 33,34,35,36,37,38,39, 41,42,43, 46, 47, 49,50,51,52, 54,55,56,57,58,59,60,61,62, 64, 66,67,68, 70,71,72,73, 90,91,92,93,94,95,96,97,98,99,100, 102]

 Dilution

15 (19.48%)

[14, 15, 17, 18, 20, 21, 23, 26, 30, 32, 45, 55, 63, 67, 96]

 E Test_ρ

7 (9.091%)

[33, 44, 46, 53, 54, 90, 101]

 Vitek2

4 (5.195%)

[6, 40, 48, 69]

 Not mentioned

2 (2.597%)

[9, 65]

 CLSI°

59 (76.623%)

[6, 13,14,15,16,17,18,19,20,21,22,23,24,25,26, 30,31,32,33,34,35,36, 38,39,40,41,42,43, 45, 47,48,49,50,51,52,53,54,55,56,57,58, 60,61,62,63,64, 66,67,68,69, 71, 90, 91, 93,94,95,96, 99, 101]

 EUCAST^γ

2 (2.597%)

[30, 37]

 Not mentioned

17 (22.078%)

[9, 10, 27,28,29, 44, 46, 59, 65, 70, 72, 73, 92, 97, 98, 100, 102]