Recent Advances in Direct Blood Culture Phenotypic Antimicrobial Susceptibility Testing

Increasing rates of antibiotic resistance make selecting empiric therapy challenging for the treatment of sepsis and suspected bloodstream infections (BSIs). The time to initiation of effective therapy for BSIs is critical for positive patient outcomes. Recent advances in rapid diagnostics for the detection of BSIs directly from positive blood culture include rapid organism identification and rapid antimicrobial susceptibility testing (AST). Rapid AST methods include genotypic and phenotypic methods or a combination of both and provide important information to aid in the prompt initiation of effective therapy. Genotypic AST methods allow rapid direct detection of a resistance mechanism but may fail to accurately predict a full susceptibility profile, whereas phenotypic AST provides comprehensive results but is not rapid if conventional methods are used. Efforts to decrease the turnaround time of phenotypic AST are an important advancement for the treatment of BSIs. Here, we review currently available and in-development phenotypic methods for AST directly from positive blood culture and their potential benefits for antimicrobial stewardship and patient care.