Time-kill curves for tebipenem, meropenem, and levofloxacin versus E. coli and K. pneumoniae. Compounds were added to cultures at time zero, and samples were processed as described in Materials and Methods. Circles, growth control; squares, tebipenem at 1× MIC; open diamonds, tebipenem at 2× MIC; triangles, tebipenem at 4× MIC; inverted triangles, tebipenem at 8× MIC; stars, meropenem at 4× MIC; solid diamonds, levofloxacin at 4× MIC.