Table 2 Description of phenotypic, commercially available methods of antimicrobial susceptibility testing
From: Next-generation rapid phenotypic antimicrobial susceptibility testing
Technology principles | Detailed technology description | Commercial name | Company or organization | Advantagesa | Limitationsa |
|---|---|---|---|---|---|
Macroscopic growth measured visually | Direct visualization of bacterial growth on solid media following exposure to antimicrobial gradient strips | ETEST®81 | bioMérieux SA | No instruments required Low barrier to implementation | Pure culture required Skilled interpretation required |
Direct visualization of bacterial growth on solid media following exposure to antimicrobial gradient strips | MTS™ (MIC Test Strip)82 | Liofilchem S.r.l. | No instruments required Low barrier to implementation | Pure culture required Skilled interpretation required | |
Direct visualization of bacterial growth on solid media after exposure to antimicrobial discs; plates inoculated directly from positive blood cultures | Rapid AST directly from positive blood cultures27 | EUCAST | No instruments required Direct from positive blood culture | Not suited to laboratories with fixed daily workflow Results are preliminary only – final AST results using conventional methods required Currently validated for 8 species only | |
Bacterial concentration detected via light absorbance | Directly read or automated broth microdilution available in pre-formatted cassettes | ComASP®83 | Liofilchem S.r.l. | No instruments required | Pure culture required |
Automated broth microdilution | VITEK® 284 | bioMérieux SA | Automated; part of extensive instrument ecosystem | Pure culture required Manual dilution steps required | |
Automated broth microdilution using metabolic indicator dye and light absorbance measurements | BD Phoenix™85 | Becton Dickinson and Company | Automated; part of extensive instrument ecosystem | Pure culture required Manual dilution steps required | |
Visualization of bacterial concentration during exposure to antimicrobials using light absorbance measurements; presence of indicator dye not specified | ASTar®28 | Q-linea AB | Does not require manual dilution steps | Pure culture required | |
Bacterial concentration detected via fluorescence production | Automated broth microdilution using fluorescence detection and universal fluorescent dye | Sensititre™86 | Thermo Fisher Scientific, Inc. | No instruments required Customizable choice of antimicrobials | Pure culture required Manual dilution steps required |
Visualization of bacterial concentration during exposure to antimicrobials using fluorescence detection and universal fluorescent dye | DxM MicroScan WalkAway ID/AST System87 | Beckman Coulter, Inc. | Automated; part of extensive instrument ecosystem | Pure culture required Manual dilution steps required | |
Visualization of proportion of viable bacteria during exposure to antimicrobials using flow cytometry and universal fluorescent dyes with single-cell resolution | FASTinov AST29 | FASTinov S.A. | Direct from positive blood culture Rapid TAT of 2 h from positive blood cultures | Flow cytometry instrument required Requires separate workflow for species ID | |
Bacterial concentration detected via advanced imaging or laser-based methods | Visualization of bacterial concentration during exposure to antimicrobials using laser light scattering | Alfred 60/AST30 | Alifax S.r.l. | Integrated liquid culture and AST system that begins AST as soon as culture ready | Requires separate workflow for species ID |
Visualization of bacterial replication during exposure to antimicrobials using microcolony-resolution light microscopy | dRAST™31 | QuantaMatrix Inc. | Direct from positive blood culture Rapid TAT of 4 h from positive blood cultures Runs 12 samples simultaneously | Requires separate workflow for species ID | |
Visualization of individual bacterial replication during exposure to antimicrobials using phase contrast microscopy within nanofluidic channels | PA-100 AST System88 | SYSMEX Europe SE | Direct from urine specimen Rapid TAT of 45 min from sample insertion No sample preparation; designed for point-of-care use | Does not provide species ID Does not work with samples containing more than one organism Urine specimens only One sample per run | |
Visualization of bacterial replication during exposure to antimicrobial gradients within a microfluidic device using single-cell resolution dark field microscopy | QuickMIC®32 | Gradientech AB | Direct from positive blood culture Rapid TAT of 4 h from positive blood cultures Modular | Only has gram-negative AST panel available Requires separate workflow for species ID | |
Bacterial concentration detected via physical interactions | Detection of individual bacterial mass during exposure to antimicrobials using a cantilever within microfluidic channel | LifeScale33 | Affinity Biosensors | Direct from positive blood culture Rapid TAT of 4.5 h from positive blood cultures Runs 4 patient samples simultaneously | Only has gram-negative AST panel available Requires separate workflow for species ID |
Bacterial growth measured indirectly via metabolic activity | Detection of bacterial metabolic changes during exposure to antimicrobials using microcantilever movements after bacterial attachment to cantilever | Resistell™34 | Resistell AG | Direct from positive blood culture Rapid TAT of 2 h from positive blood cultures Runs 12 samples simultaneously | Requires separate workflow for species ID |
Detection of gaseous bacterial metabolic products during exposure to antimicrobials using colour-changing sensors monitored via camera | VITEK® REVEAL™35 | bioMérieux SA | Direct from positive blood culture Rapid TAT of 6 h from positive blood cultures Modular | Requires separate workflow for species ID | |
Bacterial concentration and/or activity measured via multiple methods | Visualization of bacterial replication during exposure to antimicrobials using both fluorescence and dark field microscopy with universal rRNA probes; image processing via morphokinetic cellular analysis (incorporates multiple imaging features of growth at single-cell resolution); performs automated removal of sample matrix via gel electrophoresis prior to assay | Accelerate Pheno®36 | Accelerate Diagnostics, Inc. | Integrated species ID Direct from positive blood culture Rapid TAT of 7 h from positive blood cultures Modular | |
Visualization of bacterial surface area during exposure to antimicrobials using both fluorescence microscopy and charge-based fluorescent dye with specific binding to bacterial surface as well as visualization of metabolic activity using a metabolic indicator dye and light absorbance measurements | Selux Next Generation Phenotyping System89 | Selux Diagnostics, Inc. | Automated Direct from positive blood culture Rapid TAT of 7 h from positive blood cultures | Requires separate workflow for species ID |
