Evaluation of a new Rapid Antimicrobial Susceptibility system for Gram-negative and Gram-positive bloodstream infections: speed and accuracy of Alfred 60AST

Abstract

BackgroundBlood stream infections (BSIs) are a major cause of morbidity and mortality. The time from taking blood cultures to obtain results of antibiotic sensitivity can be up to five days which impacts patient care. The Alfred 60 AST™ can reduce laboratory time from positive culture bottle to susceptibility results from 16 to 25 h to 5–6 h, transforming patient care. To evaluate the diagnostic accuracy of a rapid antimicrobial susceptibility system, the Alfred 60 AST™, in clinical isolates from patients with BSIs and confirm time to results. 301 Gram-negative and 86 Gram-positive isolates were analysed directly from positive blood culture bottles following Gram staining. Antimicrobial susceptibility results and time-to-results obtained by rapid Alfred 60 AST system and BD Phoenix were compared .ResultsA total of 2196 antimicrobial susceptibility test results (AST) were performed: 1863 Gram-negative and 333 Gram-positive. AST categorical agreement (CA) for Alfred 60 AST™ was 95% (1772/1863) for Gram-negative and 89% (295/333) for Gram-positive isolates. Gram-negative CA: ampicillin 96% (290/301); ciprofloxacin 95% (283/297); ceftriaxone 96% (75/78); meropenem 97% (288/297); piperacillin-tazobactam 95% (280/295); gentamicin 94% (279/297) and amikacin 93% (277/298). The median time to susceptibility results from blood culture flagging positive was 6.3 h vs 20 h (p < 0.01) for Alfred system vs BD Phoenix™.ConclusionAlfred 60 AST system greatly reduced time to antimicrobial susceptibility results in Gram-negative and Gram-positive BSIs with good performance and cost, particularly for Gram-negative bacteraemia.

Antimicrobial susceptibility testing determined by Alfred 60/AST (Alifax®) in a multi-sites lab: performance's evaluation and optimization of workflow

“…showed a CA of 100% for both ampicillin and vancomycin. For staphylococci, Alfred 60/AST cannot detect inducible clindamycin resistance as we obtained a high rate of VME (40.9%) such as those of other studies (12% to 29.4%)(Anton-Vazquez et al, 2019;Van den Poel et al, 2020).…”

Ultrasensitive and rapid identification of ESRI developer- and piperacillin/tazobactam-resistant Escherichia coli by the MALDIpiptaz test

“…Although this method is cheap and easy to perform in a clinical microbiology laboratory, it is only designed for E. coli growing in blood culture bottles and requires an additional delay of at least 3 h compared with the MALDIpiptaz test ( Figure 6 ). Similarly, automated commercial laser scattering based in vitro (Alfred 60 AST™) has provided P/T susceptibility in E. coli directly from positive blood culture bottles within 4–6 h [ 30 ]. In addition, RAST (rapid antimicrobial susceptibility testing) based on disk diffusion was established by EUCAST to determine within 6 h the susceptibility of P/T in E. coli from positive blood culture [ 31 , 32 ].…”

Semirapid Detection of Piperacillin/Tazobactam Resistance and Extended-Spectrum Resistance to β-Lactams/β-Lactamase Inhibitors in Clinical Isolates of Escherichia coli

“…Other similar tests have been developed and/or commercialized for the detection of extended spectrum β-lactamases (ESBL) or carbapenemases, such as the ESBL NDP test ( 20 ), the Rapidec Carba NP test ( 21 ), the Nitro-Carba test ( 22 ), and matrix-assisted laser desorption ionization–time of flight mass spectrometry (MALDI-TOF MS) ( 23 ), among others. In addition, manual and automatic methods like rapid antimicrobial susceptibility testing (RAST) and the automated commercial laser-scattering-based in vitro system Alfred 60AST have been developed to identify TZP-resistant E. coli from positive blood culture bottles within 4 to 6 h ( 24 , 25 ). The main difference from these interesting tests is that the ESRI test was designed to detect not only TZP-resistant isolates but also ESRI developer isolates, which are primarily susceptible to TZP.…”