In vitro resistance studies with bacteria that exhibit low mutation frequencies: prediction of "antimutant" linezolid concentrations using a mixed inoculum containing both susceptible and resistant Staphylococcus aureus.

ABSTRACT: Bacterial resistance studies using in vitro dynamic models are highly dependent on the starting inoculum that might or might not contain spontaneously resistant mutants (RMs). To delineate concentration-resistance relationships with linezolid-exposed Staphylococcus aureus, a mixed inoculum containing both susceptible cells and RMs was used. An RM selected after the 9th passage of the parent strain (MIC, 2 μg/ml) on antibiotic-containing media (RM9; MIC, 8 μg/ml) was chosen for the pharmacodynamic studies, because the mutant prevention concentration (MPC) of linezolid against the parent strain in the presence of RM9 at 10(2) (but not at 10(4)) CFU/ml did not differ from the MPC value determined in the absence of the RMs. Five-day treatments with twice-daily linezolid doses were simulated at

SUBMITTER: Firsov AA 

PROVIDER: S-EPMC4335834 | biostudies-literature | 2015 Feb

REPOSITORIES: biostudies-literature