TABLE 1

Summary of ceftazidime-avibactam activities (MIC distributions) when tested against the main Gram-negative organisms isolated from patients hospitalized with pneumonia in U.S. medical centers (2011 to 2015)

Organism/subset (no. of isolates)aNo. of isolates (cumulative %) inhibited at ceftazidime-avibactam MIC (μg/ml) ofb:MIC (μg/ml)
≤0.060.120.250.512481632>3250%90%
P. aeruginosa (3,402)96 (2.8)221 (9.3)1,152 (43.2)1,108 (75.7)503 (90.5)206 (96.6)68 (98.6)19 (99.1)29 (100.0)24
    MEM-NS (710)2 (0.3)7 (1.3)69 (11.0)177 (35.9)221 (67.0)137 (86.3)53 (93.8)17 (96.2)27 (100.0)416
    P/T-NS (743)2 (0.3)12 (1.9)63 (10.4)176 (34.1)229 (64.9)154 (85.6)61 (93.8)18 (96.2)28 (100.0)416
    CAZ-NS (599)2 (0.3)7 (1.5)52 (10.2)146 (34.6)170 (62.9)106 (80.6)98 (92.0)19 (95.2)29 (100.0)416
    MEM-NS, P/T-NS, CAZ-NS (299)1 (0.3)10 (3.7)43 (18.1)87 (47.2)68 (69.9)48 (86.0)16 (91.3)26 (100.0)832
    MDR (613)4 (0.7)6 (1.6)46 (9.1)140 (32.0)173 (60.2)138 (82.7)60 (92.5)18 (95.4)28 (100.0)416
    XDR (365)1 (0.3)3 (1.1)18 (6.0)61 (22.7)97 (49.3)98 (76.2)44 (88.2)16 (92.6)27 (100.0)832
Enterobacteriaceae (6,209)2,264 (36.5)2,218 (72.2)1,091 (89.8)428 (96.7)144 (99.0)40 (99.6)12 (99.8)4 (99.9)5 (>99.9)0 (>99.9)3 (100.0)0.120.5
    CRE (189)11 (5.8)13 (12.7)25 (25.9)55 (55.0)58 (85.7)19 (95.8)3 (97.4)1 (97.9)1 (98.4)0 (98.4)3 (100.0)0.52
    MDR (674)126 (18.7)115 (35.8)125 (54.3)156 (77.4)103 (92.7)30 (97.2)7 (98.2)4 (98.8)5 (99.6)0 (99.6)3 (100.0)0.251
    XDR (156)10 (6.4)9 (12.3)18 (23.7)48 (54.5)48 (85.3)12 (96.2)2 (96.2)3 (98.1)1 (98.7)0 (98.1)2 (100.0)0.52
Klebsiella spp. (2,260)916 (40.5)818 (76.7)292 (89.6)146 (96.1)61 (98.8)21 (99.7)3 (99.9)1 (99.9)0 (99.9)0 (99.9)2 (100.0)0.120.5
    ESBL (433)c53 (12.2)98 (34.9)96 (57.0)99 (79.9)60 (93.8)21 (98.6)3 (99.3)1 (99.5)0 (99.5)0 (99.5)2 (100.0)0.251
    MEM-NS KPN (150)10 (6.7)11 (14.0)19 (26.7)44 (56.0)45 (86.0)17 (97.3)2 (98.7)0 (98.7)0 (98.7)0 (98.7)2 (100.0)0.52
Enterobacter spp. (1,304)211 (16.2)551 (58.4)341 (84.6)132 (94.7)54 (98.8)7 (99.4)6 (99.8)0 (99.8)2 (100.0)0.120.5
    CAZ-NS (324)12 (4.6)40 (17.0)100 (47.8)105 (80.2)49 (95.4)7 (97.5)6 (99.4)0 (99.4)2 (100.0)0.251
E. coli (1,222)621 (50.8)423 (85.4)139 (96.8)27 (99.0)9 (99.8)2 (99.9)0 (99.9)0 (99.9)0 (99.9)0 (99.9)1 (100.0)0.120.25
    ESBL (235)50 (21.3)86 (57.9)71 (88.1)16 (94.9)9 (98.7)2 (99.6)0 (99.6)0 (99.6)0 (99.6)0 (99.6)1 (100.0)0.120.5
S. marcescens (716)39 (5.4)303 (47.8)263 (84.5)96 (97.9)9 (99.2)4 (99.7)0 (99.7)0 (99.7)2 (100.0)0.250.5
P. mirabilis (319)302 (94.7)13 (98.7)1 (99.1)2 (99.7)0 (99.7)0 (99.7)0 (99.7)1 (100.0)≤0.030.06
    ESBL (39)30 (76.9)6 (92.3)1 (94.9)1 (97.4)0 (97.4)0 (97.4)0 (97.4)1 (100.0)0.060.12
Citrobacter spp. (228)96 (42.1)74 (74.6)38 (91.2)12 (96.8)8 (100.0)0.120.25
Acinetobacter spp. (443)1 (0.2)2 (0.7)11 (3.2)64 (17.6)77 (35.0)78 (52.6)72 (68.8)138 (100.0)16>32
  • a MEM-NS, meropenem nonsusceptible (MIC, ≥4 μg/ml for P. aeruginosa and ≥2 μg/ml for Enterobacteriaceae); P/T-NS, piperacillin-tazobactam nonsusceptible (MIC, ≥16 μg/ml for P. aeruginosa and Enterobacteriaceae); CAZ-NS, ceftazidime nonsusceptible (MIC, ≥16 μg/ml for P. aeruginosa and ≥8 μg/ml for Enterobacteriaceae); ESBL, ESBL-screen-positive phenotype (17).

  • b Susceptibility rates are in boldface.

  • c Includes 371 K. pneumoniae and 62 K. oxytoca isolates.