Direct and indirect methods of measuring Helicobacter pylori drug susceptibility in vitro

This article outlines a number of methods for the determination of inhibitory and bactericidal activity against H. pylori. Direct methods rely on the ability of bacteria to divide and multiply and ultimately form visible colonies after subjection to antibiotic treatment. Indirect methods rely on the measurement of metabolic activity as a viability marker and are much more rapid, especially taking into account the slow growth and fastidious nature of the organism. Inhibitory concentration measurement does not indicate the bactericidal ability of a drug; inhibition of growth does not necessarily correlate with cell death. Theoretical generation of viable but nonculturable bacteria could bring in to question the validity of direct measurements based on the colony forming ability of an organism posttreatment.