Antibiotic Susceptibility Testing in Blood Using Vertical Capacitance Aptasensors

Delayed administration of appropriate antibiotics for the treatment of infections greatly reduces the chances of survival. Therefore, it is necessary to prescribe effective antibiotics in a timely manner to avoid misuse of antibiotics through a rapid antibiotic susceptibility test (AST). However, conventional AST methods involve blood culture, pure culture and susceptibility testing. Due to series of steps, the methods require more than three days. Here, we report a vertical capacitance sensor functionalized with aptamers that can detect bacterial growth and perform AST faster. Due to the heaviness of blood cells, they sunk by gravity and the influence on capacitance was reduces in vertical structure. Thus, bacterial growth in blood was monitored in real-time by measuring changes of capacitance at f = 10 kHz. Moreover, information on biofilm formation could be obtained by the measurements at f = 0.5 kHz during blood cultures. Bacterial growth and biofilms formation were inhibited above the minimal inhibitory concentration of antibiotics. Therefore, the novel vertical aptamer immobilized capacitance sensor could be applied to rapid AST from positive blood cultures without the other culture processes.