Identification and antimicrobial susceptibility testing of Gram-positive and Gram-negative bacteria from positive blood cultures using the Accelerate Pheno™ system

Abstract

Rapid identification and antimicrobial susceptibility testing remain a crucial step for early efficient therapy of bloodstream infections. Traditional methods require turnaround times of at least 2 days, while rapid procedures are often associated with extended hands-on time. The Accelerate Pheno™ System provides microbial identification results within 90 min and susceptibility data in approximately 7 h directly from positive blood cultures with only few minutes of hands-on time. The aim of this study was, therefore, to evaluate the performance of the Accelerate Pheno™ System in identification and antimicrobial susceptibility testing of both Gram-positive and Gram-negative bacteria directly from clinical blood culture samples. We analyzed 108 and 67 blood culture bottles using the Accelerate PhenoTest™ BC kit with software version v1.0 and the FDA-cleared version v1.2, respectively. Reliable identification was achieved for Enterobacteriaceae, staphylococci, and enterococci, with 76/80 (95%), 42/46 (91%), and 10/11 (91%) correct identifications. Limitations were observed in the identification of streptococci, including Streptococcus pneumoniae and Streptococcus pyogenes, and coagulase-negative staphylococci. Antimicrobial susceptibility results for Enterobacteriaceae, for amikacin, ertapenem, ciprofloxacin, gentamicin, meropenem, and piperacillintazobactam ranged between 86 and 100% categorical agreement. Using v1.2, results for ceftazidime showed 100% concordance with the reference method. For staphylococci, the overall performance reached 92% using v1.2. Qualitative tests for detection of methicillin or macrolide-lincosamide-streptogramin B (MLSB) resistance caused major and very major errors for isolates. Overall, the present data show that the Accelerate Pheno™ system can, in combination with Gram stain, be used as a rapid complementation to standard microbial diagnosis of bloodstream infections.

Rapid molecular detection of pathogenic microorganisms and antimicrobial resistance markers in blood cultures: evaluation and utility of the next-generation FilmArray Blood Culture Identification 2 panel

“…The conventional techniques have the advantage of providing accurate species identification and antimicrobial susceptibility profile but the disadvantage of requiring 1-2 additional days after signal-positive blood cultures. During the last few years, various methods have been developed to optimize the detection of the etiological agent of BSI such as fluorescence hybridization probes [9][10][11], pathogenic-specific PCR [12,13], and MALDI-TOF MS [14][15][16]. Despite the advantages of these approaches, many of them, however, comprise multiple assay steps for the purification and extraction of the microbes and their target protein or DNA.…”

Epidemiology and Clinical Characteristics of Bloodstream Infection in Patients Under Extracorporeal Membranous Oxygenation

“…Recently, rapid antimicrobial susceptibility tests (e.g., Accelerate PhenoTest TM , Accelerate Diagnostics) and molecular diagnosis of pathogens and resistant genes (e.g., T2Bacteria Panel, T2 Biosystems) were approved by the U.S. Food and Drug Administration. 27,28 When these tests become easily available in ECMO patients, the mortality due to BSI will be decreased.…”

Rapid Antimicrobial Susceptibility Testing Methods for Blood Cultures and Their Clinical Impact

“…A variety of morphological and kinetic changes in the bacteria compared with no-antimicrobial controls are used to determine MICs. The PhenoTest has been widely evaluated in the literature and has rapid turnaround time and good performance in US and European studies (46,(49)(50)(51)(52)(53)(54). In contrast, the Alfred 60AST utilizes light scattering to detect bacterial growth in a liquid-based culture broth, determining results within 3-5 h. Organism identification is not performed with this latter method and must be determined using alternative methods (47).…”