TABLE 2.

E. coli MIC values for extended-spectrum cephalosporins and aztreonam

Strainβ-lactamaseInoculum (CFU/ml)MIC (μg/ml) of antimicrobial agent(s)a:
CTXCTX-CACAZCAZ-CAATMATM-CACPDCPD-CAFEPFEP-CA
ATCC 25922None105≤0.12≤0.120.50.25≤0.12≤0.120.50.5≤0.12≤0.12
106≤0.12≤0.120.250.250.25≤0.120.50.5≤0.12≤0.12
ATCC 35218TEM-1105≤0.12≤0.12≤0.12≤0.12≤0.12≤0.120.250.25≤0.12≤0.12
106≤0.12≤0.120.25≤0.12≤0.12≤0.120.50.25≤0.12≤0.12
OC4075TEM-1105≤0.12≤0.120.50.25≤0.12≤0.120.50.25≤0.12≤0.12
106≤0.12≤0.120.50.50.25≤0.1210.5≤0.12≤0.12
OC4229TEM-1, SHV-121052≤0.12160.2516≤0.1240.50.25≤0.12
1062≤0.12320.5160.25160.50.5≤0.12
OC6028TEM-1, CTX-M-101058≤0.120.50.251≤0.12320.52≤0.12
10616≤0.1210.252≤0.1264120.25
OC4087TEM-31054≤0.1240.251≤0.121280.251≤0.12
1068≤0.12320.254≤0.12>1280.52≤0.12
OC6042TEM-101051≤0.121280.532≤0.12320.54≤0.12
1062≤0.121280.532≤0.121280.54≤0.12
OC4227TEM-121050.25≤0.1280.51≤0.12811≤0.12
1061≤0.123211≤0.128116≤0.12
OC6043TEM-2810520.25>12811280.253218≤0.12
106160.25>1282>1280.5>1282320.25
OC6044TEM-43105320.25>1282>1280.5>1281160.5
106>1280.25>1284>1280.5>1282>1280.5
OC4138AmpC10510.52142168≤0.12≤0.12
1062222443216≤0.12≤0.12
OC4136AmpC derepressed10584128641681286410.5
10684128641616>1286421
OC4249ACT-1105881616881664≤0.12≤0.12
10616161616641664128≤0.12≤0.12
  • a The antimicrobial agents were each tested alone and with clavulanic acid (CA) at 4 μg/ml. Drug abbreviations: CTX, cefotaxime; CAZ, ceftazidime; ATM, aztreonam; CPD, cefpodoxime; FEP, cefepime.