Current and emerging techniques for antibiotic susceptibility tests

Abstract

Infectious diseases caused by bacterial pathogens are a worldwide burden. Serious bacterial infection-related complications, such as sepsis, affect over a million people every year with mortality rates ranging from 30% to 50%. Crucial clinical microbiology laboratory responsibilities associated with patient management and treatment include isolating and identifying the causative bacterium and performing antibiotic susceptibility tests (ASTs), which are labor-intensive, complex, imprecise, and slow (taking days, depending on the growth rate of the pathogen). Considering the life-threatening condition of a septic patient and the increasing prevalence of antibiotic-resistant bacteria in hospitals, rapid and automated diagnostic tools are needed. This review summarizes the existing commercial AST methods and discusses some of the promising emerging AST tools that will empower humans to win the evolutionary war between microbial genes and human wits.

Rapid molecular detection of macrolide resistance

“…However, surveillance of antimicrobial resistance is a significant challenge [3,6,7], causing difficulties in obtaining a realistic threat measurement [3,6], and impairing the ability to form future projections [8]. Current methods of assessing antimicrobial resistance are extremely slow, requiring days to weeks of culture time, and are also costly in terms of laboratory materials and technician effort [9]. Correspondingly, they are deployed unevenly, biasing our estimates of AMR worldwide and inhibiting our ability to accurately assess this threat to human health [8].…”

Identification and Antibiotic‐Susceptibility Profiling of Infectious Bacterial Agents: A Review of Current and Future Trends

“…The metabolic activity of the strain such as acidification, alkalinization, and enzymatic hydrolysis of different substrates is analyzed . The AST is based on the automation of the broth microdilution assay through sensitive optical detection systems, that measure bacterial growth in the presence of antibiotics, within 24 h post incubation . The number and concentration of antibiotics tested is limited and their sensitivity is low, as a high number of viable cells is required to measure bacterial growth and turbidity changes.…”

“…The number and concentration of antibiotics tested is limited and their sensitivity is low, as a high number of viable cells is required to measure bacterial growth and turbidity changes. Other relevant weaknesses include the impossibility to process directly patient samples, the absolute need of a pure culture of the pathogen, and the long processing time (several hours for identification and up to 18 h for AST) . The major advantages are their high degree of standardization according to the international guidelines criteria of CLSI and/or EUCAST, and their capacity to manage high workloads.…”

“…In contrast to competitor systems, the oCelloScope does not analyze single cells, but populations, and has lower resolution imaging. However, it has the advantage to allow bacterial growth measurement, without the need to attach the bacterial cells to an inert surface, a step that is required by other tools …”

“…Once they infect the specific bacterial‐host, luciferase gene expression is triggered. The signal (light) produced by luciferase‐associated enzymatic reactions is quantified and correlated to the number of cells in a sample . Other phage‐based tests are already available for diagnosis/treatment, such as the FDA‐cleared KeyPath MRSA/MSSA Blood Culture Test, which detects the presence of S. aureus directly on blood cultures.…”