[Rapid determination of bactericidal kinetics by evaluating intracellular adenosine-triphosphate in bioluminescence]

Killing kinetics measurement is usually time-consuming and tedious. Bioluminescent adenosine-triphosphate (ATP) assay, after intracellular nucleotide release by bacterial lysis, selects very quickly normal from antibiotic-modified and dead bacteria. Two simultaneous assays are performed with more and less strong lysis reagents (nucleotide releasing bacterial NRB, nucleotide releasing somatic NRS, Lumac). Bioluminescence produced in a luciferine - luciferase system is measured with Biocounter M 2010 luminometer. Differential values of two assays reflect the intracellular ATP fraction of strongest bacteria in tested cultures. Killing curves of some beta lactamines (aminopenicillin and cephalosporins) were studied with active Escherichia coli and Streptococcus pneumoniae cultures. Bactericidal action was seen within few hours, and similar variations of intracellular ATP fraction and numbers of colony-forming units obtained by reference method were observed. This method, well-suited to large series of assays and very rapid (intracellular ATP assay within one minute), performs detailed killing kinetics in real time.