TABLE 5.

In vitro activities of antimicrobial agents against gram-negative aerobic organisms

Organism (no. of isolates)MIC50/MIC90 (μg/ml [% susceptible])a
ETPIPMP/TA/CCFLCAZCIPLVXMXFGMAMKDOXT/S
Enterobacteriaceae groupb (98)≤0.125/≤0.125 (99)0.25/2 (100)≤1/4 (96)8/>64 (55)8/>32 (52)≤0.5/≤0.5 (94)≤0.5/≤0.5 (94)≤0.5/1 (94)≤0.25/2 (94)≤2/≤2 (95)≤8/≤8 (99)2/16 (79)≤0.5/>4 (90)
Proteus-Providencia-Morganella groupc (55)≤0.125/≤0.125 (98)4/4 (100)≤1/≤1 (98)8/>64 (58)≤0.5/8 (93)≤0.5/≤0.5 (95)≤0.5/≤0.5 (95)≤0.25/2 (91)≤2/≤8 (98)≤2/≤2 (100)>32/>32 (22)≤0.5/>4 (91)
P. aeruginosa (43)8/16 (NId)1/4 (86)4/16 (98)1/4 (98)≤.5/1 (91)≤.5/8 (79)1/8 (74)≤2/4 (95)≤8/≤8 (100)
S. maltophilia (15)>16 (NI)>16 (NI)>128/>128 (NI)64/64 (NI)8/>32 (53)2/>8 (NI)1/>8 (80)0.5/4 (NI)>32/>32 (NI)128/>128 (NI)4/4 (NI)>4/>4 (20)
Miscellaneous nonfermenting gram-negative rodse (24)≤.125/>16 (63)0.25/4 (92)≤1/>128 (79)4/>64 (67)4/>32 (79)1/>8 (58)≤0.5/>8 (83)1/>8 (71)≤2/8 (83)≤1/128 (79)≤1/>32 (75)≤0.5/>4 (75)
  • a ETP, ertapenem; IPM, imipenem; P/T, piperacillin-tazobactam; A/C, amoxicillin-clavulanic acid; CFL, cephalexin; CAZ, ceftazidime; CIP, ciprofloxacin; LVX, levofloxacin; MXF, moxifloxacin; GM, gentamicin; AMK, amikacin; DOX, doxycycline; T/S, trimethoprim-sulfamethoxazole.

  • b Escherichia coli (n = 20), Enterobacter cloacae (n = 21), Enterobacter aerogenes (n = 7), Enterobacter gergoviae (n = 1), Enterobacter intermedius (n = 1), Citrobacter freundii (n = 1), Citrobacter koseri (n = 4), Klebsiella oxytoca (n = 16), Klebsiella pneumoniae (n = 9), Pantoeae agglomerans (n = 3), and Serratia marcescens (n = 15).

  • c Proteus mirabilis (n = 26), Proteus vulgaris (n = 4), Providencia rettgeri (n = 6), Providencia rustigianii (n = 1), Providencia stuartii (n = 1), and Morganella morganii (n = 17).

  • d NI, no interpretation.

  • e Alcaligenes faecalis (n = 10), Acinetobacter baumannii (n = 6), Acinetbacter calcoaceticus (n = 1), Brevundimonas diminuta (n = 1), Chryseobacterium sp. (n = 1), Myroides odoratum (n = 1), Paracoccus sp. (n = 1), Pseudomonas fluorescens (n = 2), and Shewanella putrefaciens (n = 1).