Figure 1

Cell morphology of MG1655/CTX-M-1, MG1655/IncI1/CTX-M-1, MG1655/NCS and MG1655/IncI1/NCS cultured with and without cefotaxime. (A) Filmentation at different cefotaxime concentrations. Pictures are taken in early exponential phase, except where stated otherwise. (1–5) MG1655/CTX-M-1 cultured without cefotaxime, with 4 mg/L cefotaxime, with 16 mg/L cefotaxime, with 32 mg/L cefotaxime and with 256 mg/L cefotaxime, respectively. (6–10) MG1655/IncI1/CTX-M-1 cultured without cefotaxime, with 4 mg/L cefotaxime, with 16 mg/L cefotaxime, with 64 mg/L cefotaxime and with 256 mg/L cefotaxime, respectively. Picture (5) and (10) were taken in late stationary phase. (11–12) MG1655/NCS cultured without cefotaxime and with 0.016 mg/L cefotaxime, respectively. (13–14) MG1655/IncI1/NCS cultured without cefotaxime and with 0.032 mg/L cefotaxime, respectively. (B) Filamentation and growth phase dependency. The growth curves are representative drawings, where the morphology of the cells (resistant or sensitive) is marked at different growth phases. The strains were grown in MH-2 broth with and without cefotaxime on an oCelloScope.