Determining bacteriostatic and bactericidal activity of antibiotics, by measuring amounts of bacterial DNA in test and control samples, useful for intracellular and axenic species

摘要

Determining the bacteriostatic or bactericidal activity of an antibiotic (I) with respect to a selected bacterium comprising comparing numbers of copies of bacterial DNA in cultures treated with (I) or untreated, is new. Determining the bacteriostatic or bactericidal activity of an antibiotic (I) with respect to a selected bacterium comprises: (a) culturing the bacterium in presence and absence of (I) for a defined period so that the bacterial titer in the (I)-free culture increases by at least 100 fold; (b) extracting DNA from the starting inoculum and from the cultures; enzymatic amplification of (part of) a bacterial gene by the same quantitative PCR method, to determine the quantity of bacterial DNA in each sample; (c) comparing the number of DNA copies in the inoculum with that in the cultures and deducing bacteriostatic or bactericidal activity if the number of copies in the (I)-containing culture is: (i) lower than, or equal to, the number in the inoculum; and (ii) lower than the number in the (I)-free culture. An Independent claim is also included for a kit for the process.