Conventional antimicrobial susceptibility testing (AST)
methods
require 24–48 h to provide results, creating the need for a
probabilistic antibiotic therapy that increases the risk of antibiotic
resistance emergence. Consequently, the development of rapid AST methods
has become a priority. Over the past decades, sedimentation field-flow
fractionation (SdFFF) has demonstrated high sensitivity in early monitoring
of induced biological events in eukaryotic cell populations. This
proof-of-concept study aimed at investigating SdFFF for the rapid
assessment of bacterial susceptibility to antibiotics. Three bacterial
species were included (Escherichia coli, Klebsiella pneumoniae, and Pseudomonas aeruginosa) with two panels of antibiotics
tailored to each bacterial species. The results demonstrate that SdFFF,
when used in “Hyperlayer” elution mode, enables monitoring
of antibiotic-induced morphological changes. The percentage variation
of the retention factor (PΔR) was used to quantify
the biological effect of antibiotics on bacteria with the establishment
of a threshold value of 16.8% to differentiate susceptible and resistant
strains. The results obtained with SdFFF were compared to that of
the AST reference method, and a categorical agreement of 100% was
observed. Overall, this study demonstrates the potential of SdFFF
as a rapid method for the determination of antibiotic susceptibility
or resistance since it is able to provide results within a shorter
time frame than that needed for conventional methods (3–4 h
vs 16–24 h, respectively), enabling earlier targeted antibiotic
therapy. Further research and validation are necessary to establish
the effectiveness and reliability of SdFFF in clinical settings.