Factors influencing the response of Escherichia coli to antibiotics in conditions prevailing in the infected urinary bladder.

The response of a sensitive strain of Escherichia coli to a variety of antibiotics was examined in an in vitro model which simulates the hydrokinetic features of the urinary bladder. Recovery of bacterial cultures from antibiotic effects was observed following exposure to bactericidal and bacteristatic antibiotics and no substantial difference was noted between the effectiveness of bacteristatic and bactericidal agents except that bacteristatic antibiotics were more influenced by alteration of the conditions of "diuresis" and "frequency of micturition". The response of dense bacterial populations to high concentrations of 3 beta-lactam antibiotics varied markedly under the different hydrokinetic conditions. Possible reasons for these variations are discussed.