Growth curve patterns and bacterial morphology of Escherichia coli subjected to different temocillin (BRL17421) concentrations

β-Lactam antibiotics have different modes of action which may be reflected by different morphological modifications of bacteria. A relationship may be found between the growth curve pattern and the bacterial morphology of Escherichia coli subjected to different β-lactams. Temocillin induced filament formation followed by lysis depending upon time and concentration. The growth curve patterns and particularly the early response (first 2 h of contact between antibiotic and bacteria) showed a residual growth that was hardly dependent on concentration around the minimum inhibitory concentrations (MICs) (from one quarter to four times the MIC) but was concentration dependent from 8 to 20 times the MIC. The target of temocillin on the bacterial cell wall probably changes according to time and concentration.