High-throughput quantification of population dynamics using luminescence
Bacterial population decline at antibiotic concentrations above the minimum inhibitory concentration (MIC) remains poorly characterized. This is because colony-forming units (CFU), the standard method to quantify inhibition, are slow, labor-intensive, and costly. Luminescence assays are widely used to quantify population dynamics at subinhibitory concentrations, yet their limitations and…
The luminescence assay, a rapid and cost-effective method for tracking bacterial population dynamics, has been found to provide comparable results to colony-forming unit (CFU) counts in certain situations. Researchers compared luminescence and CFU-based rates in 20 antibiotics, and discovered that the two methods did not differ significantly for half of the tested antibiotics. For the remaining half, CFU-based decline rates were consistently higher than those estimated by luminescence.
This discrepancy can be attributed to two key factors. Firstly, light intensity, which luminescence measures, tracks biomass more accurately than population size. As bacteria filament, luminescence declines more slowly than the actual population. Secondly, CFU-based estimates tend to show a steeper decline when the antimicrobial reduces the number of colonies formed per plated bacterium.
This difference can stem from changes in bacterial clustering, alterations in culturability due to physiological changes, or the presence of residual antimicrobial agents.
The researchers conclude that the effectiveness of luminescence in quantifying bacterial decline hinges on the specific physiological effects of the antimicrobial and whether the primary interest lies in cell number or biomass. While this high-throughput alternative may have limitations, it offers a valuable tool for investigating bacterial dynamics at super-MIC concentrations.
Written by urgent.news from eLife's reporting — not their text. Machine-written — it may contain errors, so check the original before relying on it.
