| Summary: | The minimal inhibitory concentration (MIC) is conventionally used to define in vitro levels of susceptibility or resistance of a specific bacterial strain to an antibiotic and to predict its clinical efficacy. Along with MIC, other measures of bacteria resistance exist: the MIC determined at high bacterial inocula (MIC<sub>HI</sub>) that allow the estimation of the occurrence of inoculum effect (IE) and the mutant prevention concentration, MPC. Together, MIC, MIC<sub>HI</sub> and MPC represent the bacterial “resistance profile”. In this paper, we provide a comprehensive analysis of such profiles of <i>K. pneumoniae</i> strains that differ by meropenem susceptibility, ability to produce carbapenemases and specific carbapenemase types. In addition, we have analyzed inter-relations between the MIC, MIC<sub>HI</sub> and MPC for each tested <i>K. pneumoniae</i> strain. Low IE probability was detected with carbapenemase-non-producing <i>K. pneumoniae,</i> and high IE probability was detected with those that were carbapenemase-producing. MICs did not correlate with the MPCs; significant correlation was observed between the MIC<sub>HI</sub>s and the MPCs, indicating that these bacteria/antibiotic characteristics display similar resistance properties of a given bacterial strain. To determine the possible resistance-related risk due to a given <i>K. pneumoniae</i> strain, we propose determining the MIC<sub>HI</sub>. This can more or less predict the MPC value of the particular strain.
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