Nanoscale effects of antibiotics on P. aeruginosa.

Studying living bacteria at the nanoscale in their native liquid environment opens an unexplored landscape. We focus on Pseudomonas aeruginosa and demonstrate how the cell wall is biophysically affected at the nanoscale by two reference antibiotics (ticarcillin and tobramycin). The elasticity of the cells drops dramatically after treatment (from 263 ± 70 kPa to 50 ± 18 and 24 ± 4 kPa, respectively on ticarcillin- and tobramycin-treated bacteria) and major micro- and nano-morphological modifications are observed (the surface roughness of native, ticarcillin- and tobramycin-treated bacteria are respectively 2.5, 0.8, and 4.4 nm for a surface area of 40,000 nm²). Thus the nanoscale approach in liquid is valid and can be extended. Pseudomonas aeruginosa cell wall was demonstrated to be biophysically affected at the nanoscale by two reference antibiotics, ticarcillin, and tobramycin, with the elasticity dropping dramatically after treatment.