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. 2020 Jul 3;6(27):eabb9593. doi: 10.1126/sciadv.abb9593

Fig. 1. Nanomechanical properties of BLS and BLR Gram-negative bacteria.

Fig. 1

(A) Heat map representation of antimicrobial resistance of five Salmonella isolates, five E. coli isolates, six P. aeruginosa isolates, and six K. pneumoniae isolates on a logarithmic color scale. Red represents a high level of antibiotic resistance (MIC ≥ 64 μg/ml), while blue represents a low level of antibiotic resistance (MIC ≤ 0.125 μg/ml). PEN, penicillin; AMP, ampicillin; PIP, piperacillin; AMC, amoxicillin-clavulanic acid; OXA, oxacillin; CAZ, ceftazidime; FEP, cefepime; CTX, cefotaxime; CRO, ceftriaxone; CXM, cefuroxime; CZO, cefazolin; IPM, imipenem; MEM, meropenem; BIPM, biapenem; ATM, aztreonam. (B) Strategy for measuring stiffness of Gram-negative bacteria using liquid AFM with a bacterium immobilized on a poly-l-lysine–coated glass substratum. (C) AFM topographic image recorded in PBS showing S.79 on a modified substratum. Scale bar, 500 nm. (D) The height profile along the white dotted line in the image (C). (E) Representative Derjaguin-Muller-Toporov Young’s modulus map of S.79. Scale bar, 1 μm. (F) A high-magnification elasticity map is shown, and the enlarged section is outlined in white in (E). Scale bar, 200 nm. (G to J) Quantification of the average Young’s modulus of the five Salmonella isolates (G), five E. coli isolates (H), six P. aeruginosa isolates (I), and six K. pneumoniae isolates (J). The BLS isolates are indicated with a pink band, while the BLR isolates are indicated with a blue band in (G to J). Thick horizontal lines and error bars represent mean and SD, respectively. Student’s t test, **P < 0.01.