Rapid antimicrobial susceptibility testing of clinical isolates by digital time-lapse microscopy

Abstract

Rapid antimicrobial susceptibility testing (AST) is essential for early and appropriate therapy. Methods with short detection time enabling same-day treatment optimisation are highly favourable. In this study, we evaluated the potential of a digital time-lapse microscope system, the oCelloScope system, to perform rapid AST. The oCelloScope system demonstrated a very high accuracy (96 % overall agreement) when determining the resistance profiles of four reference strains, nine clinical isolates, including multi-drug-resistant isolates, and three positive blood cultures. AST of clinical isolates (168 antimicrobial agent–organism combinations) demonstrated 3.6 % minor, no major and 1.2 % very major errors of the oCelloScope system compared to conventional susceptibility testing, as well as a rapid and correct phenotypic detection of strains with methicillin-resistant Staphylococcus aureus (MRSA) and extended-spectrum β-lactamase (ESBL) profiles. The net average time-to-result was 108 min, with 95 % of the results being available within 180 min. In conclusion, this study strongly indicates that the oCelloScope system holds considerable potential as an accurate and sensitive AST method with short time-to-result, enabling same-day targeted antimicrobial therapy, facilitating antibiotic stewardship and better patient management. A full-scale validation of the oCelloScope system including more isolates is necessary to assess the impact of using it for AST.

New and developing diagnostic technologies for urinary tract infections

“…The system was able to detect an initial change in growth rate in response to antibiotics — such as levofloxacin or combination ticarcillin and clavulanic acid — in only 30 minutes, and determine the minimum inhibitory concentration (MIC) in <3 hours. In a second study, nine clinical isolates from patient blood cultures, including multidrug-resistant strains, were compared with reference strains to evaluate the oCelloScope system AST 99 . The study results showed 96% agreement between the real-time microscopy and standard AST methods.…”

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

“…[59] In gram-positive bacteria, MALDI-TOF MS can be used to discriminate between E. faecium vanB positive and negative strains. [64] However, discrimination between MSSA and MRSA strains is contradictory, as some authors described measurable differences in the spectra, [65,66] while others considered such differences attributable to clonality. [67,68] The difficulty in using MALDI-TOF MS directly on a clinical sample is due to the high amount of host proteins, This problem can be minimized by applying time consuming sample preparation methods.…”

“…This system was evaluated in several experiments, such as monoculture infection, with results obtained in 6 min for E. coli isolates and in 30 min for complex samples such as urine collected from pigs with catheter‐associated UTIs . It was also evaluated in positive blood cultures and the average time to obtain susceptibility degree values ranged from 1 to 4.2 h depending on the bacteria–antibiotic combination . In contrast to competitor systems, the oCelloScope does not analyze single cells, but populations, and has lower resolution imaging.…”

Three-dimensional label-free observation of individual bacteria upon antibiotic treatment using optical diffraction tomography

“…A basic approach to understanding the mechanism of antibiotics is to observe the phenotypic or physical response of bacteria to antibiotics. Phenotypic imaging has been one of the most popular diagnostic methods to achieve rapid antimicrobial susceptibility testing [5][6][7][8][9][10], as it provides an easy, low cost, real-time single-cell level examination. Furthermore, phenotypic analysis of bacteria has been exploited to extract useful information in various fields such as epidemiology and systems biology [11].…”