Jonasson E, Matuschek E, Kahlmeter G. The EUCAST rapid disc diffusion method for antimicrobial susceptibility testing directly from positive blood culture bottles.
J Antimicrob Chemother 2021;
75:968-978. [PMID:
32016342 PMCID:
PMC7069491 DOI:
10.1093/jac/dkz548]
[Citation(s) in RCA: 49] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2019] [Revised: 12/03/2019] [Accepted: 12/09/2019] [Indexed: 12/25/2022] Open
Abstract
Objectives
With increasing antimicrobial resistance, rapid antimicrobial susceptibility testing (RAST) becomes important, especially in patients with bloodstream infections. EUCAST decided to develop a standardized rapid method, based on EUCAST disc diffusion, to offer susceptibility reports within 4–8 h of a positive blood culture (BC).
Methods
BC bottles were spiked with clinical isolates (n = 332) of the seven most relevant sepsis pathogens with a variety of resistance mechanisms. RAST was performed directly from the bottle and zones read after 4, 6 and 8 h. Several variables were investigated, including the effect of using different BC bottles and of a 0–18 h delay between a positive signal and the performance of RAST.
Results
For five species, most inhibition zones could be read after 4 h. The proportion of results that could be interpreted increased from 75% at 4 h to 84% after 8 h. Categorical agreement against the reference method was good, with error rates of false susceptibility of 0.2%, 0.2% and 0.2% at 4, 6 and 8 h and false resistance of 1.2%, 0.2% and 0.1% at 4, 6 and 8 h, respectively.
Conclusions
With the EUCAST RAST method, reliable AST results can be delivered within 4–8 h of positivity of BC bottles for seven important bloodstream infection pathogens. To reduce the occurrence of errors and to absorb the variability caused by using a non-standardized inoculum, material from different manufacturers and workflow-related delays, we have introduced an area in which interpretation is not permitted, the Area of Technical Uncertainty.
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