TABLE 2

Ceftazidime-avibactam and ceftazidime MIC distributions for meropenem-nonsusceptible Enterobacteriaceae that were carbapenemase negative, KPC positive, OXA-48 positive, GES positive, or metallo-β-lactamase positive and ceftazidime-avibactam distributions stratified by the presence or absence of an ESBL or AmpC β-lactamase gene

Genotype/organism (n)Antimicrobial agentNo. (%) of isolates inhibited at MIC (μg/ml) ofa:
≤0.0150.030.060.120.250.51248163264128>128
Carbapenemase negative
    All (207)Ceftazidime4 (1.9)2 (2.9)4 (4.8)1 (5.3)1 (5.8)2 (6.8)4 (8.7)6 (11.6)19 (20.8)34 (37.2)43 (58.0)87 (100)
Ceftazidime-avibactam4 (1.9)15 (9.2)17 (17.4)24 (29.0)36 (46.4)60 (75.4)36 (92.8)4 (94.7)4 (96.6)1 (97.1)0 (97.1)1 (97.6)5 (100)
    AmpC positive,b ESBL positivec (16)Ceftazidime-avibactam1 (6.3)1 (12.5)2 (25.0)3 (43.8)5 (75.0)2 (87.5)1 (93.8)0 (93.8)0 (93.8)0 (93.8)1 (100)
    AmpC positive, ESBL negative (32)Ceftazidime-avibactam2 (6.3)2 (12.5)5 (28.1)3 (37.5)8 (62.5)5 (78.1)5 (93.8)0 (93.8)2 (100)
    AmpC negative, ESBL positive (147)Ceftazidime-avibactam1 (0.7)9 (6.8)10 (13.6)17 (25.2)24 (41.5)50 (75.5)29 (95.2)3 (97.3)0 (97.3)0 (97.3)0 (97.3)0 (97.3)4 (100)
    AmpC negative, ESBL negative (12)Ceftazidime-avibactam1 (8.3)3 (33.3)1 (41.7)2 (58.3)1 (66.7)0 (66.7)0 (66.7)0 (66.7)2 (83.3)1 (91.7)0 (91.7)0 (91.7)1 (100)
KPC positive, MBL negative
    All (476)dCeftazidime1 (0.2)5 (1.3)4 (2.1)16 (5.5)37 (13.2)38 (21.2)70 (35.9)54 (47.3)251 (100)
Ceftazidime-avibactam2 (0.4)12 (2.9)12 (5.5)17 (9.0)34 (16.2)83 (33.6)150 (65.1)109 (88.0)41 (96.6)10 (98.7)4 (99.6)1 (99.8)0 (99.8)1 (100)
    AmpC positive, ESBL positive (11)Ceftazidime-avibactam1 (9.1)3 (36.4)5 (81.8)1 (90.9)1 (100)
    AmpC positive, ESBL negative (19)Ceftazidime-avibactam1 (5.3)2 (15.8)0 (15.8)5 (42.1)9 (89.5)2 (100)
    AmpC negative, ESBL positive (205)Ceftazidime-avibactam1 (0.5)5 (2.9)6 (5.9)6 (8.8)13 (15.1)30 (29.8)73 (65.4)50 (89.8)18 (98.5)1 (99.0)2 (100)
    AmpC negative, ESBL negative (241)Ceftazidime-avibactam1 (0.4)7 (3.3)5 (5.4)9 (9.1)20 (17.4)45 (36.1)63 (62.2)56 (85.5)22 (94.6)9 (98.3)2 (99.2)1 (99.6)0 (99.6)1 (100)
OXA-48-like positive, MBL negative
    All (134)eCeftazidime1 (0.7)0 (0.7)3 (3.0)6 (7.5)4 (10.4)3 (12.7)7 (17.9)2 (19.4)6 (23.9)11 (32.1)26 (51.5)28 (72.4)37 (100)
Ceftazidime-avibactam1 (0.7)1 (1.5)6 (6.0)25 (24.6)46 (59.0)37 (86.6)12 (95.5)3 (97.8)1 (98.5)1 (99.3)0 (99.3)1 (100)
    AmpC positive, ESBL positive (4)Ceftazidime-avibactam2 (50.0)1 (75.0)0 (75.0)0 (75.0)0 (75.0)0 (75.0)0 (75.0)1 (100)
    AmpC positive, ESBL negative (6)Ceftazidime-avibactam2 (33.3)2 (66.7)2 (100)
    AmpC negative, ESBL positive (105)Ceftazidime-avibactam3 (2.9)19 (21.0)37 (56.2)31 (85.7)11 (96.2)3 (99.0)1 (100)
    AmpC negative, ESBL negative (19)Ceftazidime-avibactam1 (5.3)1 (10.5)3 (26.3)4 (47.4)5 (73.7)3 (89.5)1 (94.7)0 (94.7)0 (94.7)1 (100)
GES positive, MBL negative
    All (2)fCeftazidime1 (50.0)0 (50.0)1 (100)
Ceftazidime-avibactam1 (50.0)0 (50.0)1 (100)
    AmpC negative, ESBL positive (1)Ceftazidime-avibactam1 (100)
    AmpC negative, ESBL negative (1)Ceftazidime-avibactam1 (100)
MBL positive
    All (145)gCeftazidime3 (2.1)0 (2.1)0 (2.1)0 (2.1)0 (2.1)1 (2.8)4 (5.5)4 (8.3)9 (14.5)124 (100)
Ceftazidime-avibactam4 (2.8)0 (2.8)0 (2.8)0 (2.8)1 (3.4)2 (4.8)8 (10.3)8 (15.9)10 (22.8)112 (100)
    AmpC positive, ESBL positive (28)Ceftazidime-avibactam2 (7.1)2 (14.3)2 (21.4)22 (100)
    AmpC positive, ESBL negative (37)Ceftazidime-avibactam1 (2.7)1 (5.4)4 (16.2)4 (27.0)2 (32.4)25 (100)
    AmpC negative, ESBL positive (56)Ceftazidime-avibactam1 (1.8)2 (5.4)1 (7.1)4 (14.3)48 (100)
    AmpC negative, ESBL negative (24)Ceftazidime-avibactam4 (16.7)0 (16.7)0 (16.7)0 (16.7)0 (16.7)0 (16.7)0 (16.7)1 (20.8)2 (29.2)17 (100)
  • a The MIC90 is in bold type for each MIC distribution. The MIC90 was not calculated for <10 isolates.

  • b AmpC-positive isolates include organisms that carry a plasmid-mediated AmpC or are presumed to harbor an intrinsic AmpC (Citrobacter spp., Enterobacter spp., Providencia spp., and S. marcescens).

  • c ESBL-positive isolates include organisms that carry a plasmid-mediated ESBL or are presumed to harbor an intrinsic ESBL (K. oxytoca).

  • d Includes two isolates carrying KPC-2 and OXA-163 and one isolate carrying KPC-2 and GES-6; does not include six isolates carrying KPC and MBL.

  • e Includes two isolates carrying OXA-163 and KPC-2; does not include seven isolates carrying OXA-48-like β-lactamases and MBL.

  • f Includes one isolate carrying KPC-2 and GES-6.

  • g Includes 13 isolates carrying MBLs and serine carbapenemases.