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

2021 ◽  
Vol 8 ◽  
Author(s):  
Ritu Banerjee ◽  
Romney Humphries
Keyword(s):  
Clinical Outcomes ◽  
Antimicrobial Susceptibility ◽  
Susceptibility Testing ◽  
Bloodstream Infections ◽  
Blood Cultures ◽  
Clinical Impact ◽  
Antimicrobial Susceptibility Testing ◽  
Optimal Management ◽  
Testing Methods

Antimicrobial susceptibility testing (AST) of bacteria isolated in blood cultures is critical for optimal management of patients with sepsis. This review describes new and emerging phenotypic and genotypic AST methods and summarizes the evidence that implementation of these methods can impact clinical outcomes of patients with bloodstream infections.

Evaluation of standardized automated rapid antimicrobial susceptibility testing of Enterobacterales-containing blood cultures: a proof-of-principle study

2020 ◽  
Vol 75 (11) ◽  
pp. 3218-3229
Author(s):  
Stefano Mancini ◽  
Elias Bodendoerfer ◽  
Natalia Kolensnik-Goldmann ◽  
Sebastian Herren ◽  
Kim Röthlin ◽  
...  
Keyword(s):  
Standard Method ◽  
Antimicrobial Susceptibility ◽  
Susceptibility Testing ◽  
Bloodstream Infections ◽  
Inhibition Zone ◽  
Blood Cultures ◽  
Antimicrobial Susceptibility Testing ◽  
Disc Diffusion ◽  
Inhibition Zones ◽  
Reading System

Abstract Background Rapid antimicrobial susceptibility testing (RAST) of bacteria causing bloodstream infections is critical for implementation of appropriate antibiotic regimens. Objectives We have established a procedure to prepare standardized bacterial inocula for Enterobacterales-containing clinical blood cultures and assessed antimicrobial susceptibility testing (AST) data generated with the WASPLabTM automated reading system. Methods A total of 258 blood cultures containing Enterobacterales were examined. Bacteria were enumerated by flow cytometry using the UF-4000 system and adjusted to an inoculum of 106 cfu/mL. Disc diffusion plates were automatically streaked, incubated for 6, 8 and 18 h and imaged using the fully automated WASPLabTM system. Growth inhibition zones were compared with those obtained with inocula prepared from primary subcultures following the EUCAST standard method. Due to time-dependent variations of the inhibition zone diameters, early AST readings were interpreted using time-adjusted tentative breakpoints and areas of technical uncertainty. Results and conclusions Inhibition zones obtained after 18 h incubation using an inoculum of 106 cfu/mL prepared directly from blood cultures were highly concordant with those of the EUCAST standard method based on primary subcultures, with categorical agreement (CA) of 95.8%. After 6 and 8 h incubation, 89.5% and 93.0% of the isolates produced interpretable results, respectively, with CA of >98.5% and very low numbers of clinical categorization errors for both the 6 h and 8 h readings. Overall, with the standardized and automated RAST method, consistent AST data from blood cultures containing Enterobacterales can be generated after 6–8 h of incubation and subsequently confirmed by standard reading of the same plate after 18 h.

scholarly journals Evaluation of the Accelerate Pheno System for Fast Identification and Antimicrobial Susceptibility Testing from Positive Blood Cultures in Bloodstream Infections Caused by Gram-Negative Pathogens

2017 ◽  
Vol 55 (7) ◽  
pp. 2116-2126 ◽  
Author(s):  
Matthias Marschal ◽  
Johanna Bachmaier ◽  
Ingo Autenrieth ◽  
Philipp Oberhettinger ◽  
Matthias Willmann ◽  
...  
Keyword(s):  
Blood Culture ◽  
Antimicrobial Susceptibility ◽  
Susceptibility Testing ◽  
Bloodstream Infections ◽  
Test System ◽  
Blood Cultures ◽  
Antimicrobial Susceptibility Testing ◽  
Diagnostic Tools ◽  
Gram Negative ◽  
Content Type

ABSTRACT Bloodstream infections (BSI) are an important cause of morbidity and mortality. Increasing rates of antimicrobial-resistant pathogens limit treatment options, prompting an empirical use of broad-range antibiotics. Fast and reliable diagnostic tools are needed to provide adequate therapy in a timely manner and to enable a de-escalation of treatment. The Accelerate Pheno system (Accelerate Diagnostics, USA) is a fully automated test system that performs both identification and antimicrobial susceptibility testing (AST) directly from positive blood cultures within approximately 7 h. In total, 115 episodes of BSI with Gram-negative bacteria were included in our study and compared to conventional culture-based methods. The Accelerate Pheno system correctly identified 88.7% (102 of 115) of all BSI episodes and 97.1% (102 of 105) of isolates that are covered by the system's identification panel. The Accelerate Pheno system generated an AST result for 91.3% (95 of 104) samples in which the Accelerate Pheno system identified a Gram-negative pathogen. The overall category agreement between the Accelerate Pheno system and culture-based AST was 96.4%, the rates for minor discrepancies 1.4%, major discrepancies 2.3%, and very major discrepancies 1.0%. Of note, ceftriaxone, piperacillin-tazobactam, and carbapenem resistance was correctly detected in blood culture specimens with extended-spectrum beta-lactamase-producing Escherichia coli ( n = 7) and multidrug-resistant Pseudomonas aeruginosa ( n = 3) strains. The utilization of the Accelerate Pheno system reduced the time to result for identification by 27.49 h ( P < 0.0001) and for AST by 40.39 h ( P < 0.0001) compared to culture-based methods in our laboratory setting. In conclusion, the Accelerate Pheno system provided fast, reliable results while significantly improving turnaround time in blood culture diagnostics of Gram-negative BSI.

scholarly journals Use of the Accelerate Pheno System for Identification and Antimicrobial Susceptibility Testing of Pathogens in Positive Blood Cultures and Impact on Time to Results and Workflow

2017 ◽  
Vol 56 (1) ◽  
Author(s):  
Angella Charnot-Katsikas ◽  
Vera Tesic ◽  
Nedra Love ◽  
Brandy Hill ◽  
Cindy Bethel ◽  
...  
Keyword(s):  
Antimicrobial Susceptibility ◽  
Susceptibility Testing ◽  
Bloodstream Infections ◽  
Standard Of Care ◽  
Blood Cultures ◽  
Antimicrobial Susceptibility Testing ◽  
Clinical Microbiology Laboratory ◽  
Current Standard ◽  
Cellular Analysis ◽  
Hands On

ABSTRACT The Accelerate Pheno system uses automated fluorescence in situ hybridization technology with morphokinetic cellular analysis to provide rapid species identification (ID) and antimicrobial susceptibility testing (AST) results for the most commonly identified organisms in bloodstream infections. The objective was to evaluate the accuracy and workflow of bacterial and yeast ID and bacterial AST using the Accelerate Pheno system in the clinical microbiology laboratory. The consecutive fresh blood cultures received in the laboratory were analyzed by the Accelerate Pheno system within 0 to 8 h of growth detection. ID/AST performance, the average times to results, and workflow were compared to those of the routine standard of care. Of the 232 blood cultures evaluated (223 monomicrobial and 9 polymicrobial) comprising 241 organisms, the overall sensitivity and specificity for the identification of organisms were 95.6% and 99.5%, respectively. For antimicrobial susceptibility, the overall essential agreement was 95.1% and categorical agreement was 95.5% compared to routine methods. There was one very major error and 3 major errors. The time to identification and the time to susceptibility using the Accelerate Pheno system were decreased by 23.47 and 41.86 h, respectively, compared to those for the standard of care. The reduction in hands on time was 25.5 min per culture. The Accelerate Pheno system provides rapid and accurate ID/AST results for most of the organisms found routinely in blood cultures. It is easy to use, reduces hands on time for ID/AST of common blood pathogens, and enables clinically actionable results to be released much earlier than with the current standard of care.

scholarly journals EUCAST rapid antimicrobial susceptibility testing (RAST) in blood cultures: validation in 55 European laboratories

2020 ◽  
Vol 75 (11) ◽  
pp. 3230-3238
Author(s):  
Anna Åkerlund ◽  
Emma Jonasson ◽  
Erika Matuschek ◽  
Lena Serrander ◽  
Martin Sundqvist ◽  
...  
Keyword(s):  
Antimicrobial Susceptibility ◽  
Susceptibility Testing ◽  
Total Error ◽  
Bloodstream Infections ◽  
Error Rates ◽  
Blood Cultures ◽  
Antimicrobial Susceptibility Testing ◽  
Fine Tuning ◽  
Resistant Bacteria ◽  
Disc Diffusion

Abstract Objectives When bloodstream infections are caused by resistant bacteria, rapid antimicrobial susceptibility testing (RAST) is important for adjustment of therapy. The EUCAST RAST method, directly from positive blood cultures, was validated in a multi-laboratory study in Europe. Methods RAST was performed in 40 laboratories in northern Europe (NE) and 15 in southern Europe (SE) from clinical blood cultures positive for Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, Staphylococcus aureus or Streptococcus pneumoniae. Categorical results at 4, 6 and 8 h of incubation were compared with results for EUCAST standard 16–20 h disc diffusion. The method, preliminary breakpoints and the performance of the laboratories were evaluated. Results The total number of isolates was 833/318 in NE/SE. The number of zone diameters that could be read (88%, 96% and 99%) and interpreted (70%, 81% and 85%) increased with incubation time (4, 6 and 8 h). The categorical agreement was acceptable, with total error rates in NE/SE of 2.4%/4.9% at 4 h, 1.1%/3.5% at 6 h and 1.1%/3.3% at 8 h. False susceptibility at 4, 6 and 8 h of incubation was below 0.3% and 1.1% in NE and SE, respectively, and the corresponding percentages for false resistance were below 1.9% and 2.8%. After fine-tuning breakpoints, more zones could be interpreted (73%, 89% and 93%), with only marginally affected error rates. Conclusions The EUCAST RAST method can be implemented in routine laboratories without major investments. It provides reliable antimicrobial susceptibility testing results for relevant bloodstream infection pathogens after 4–6 h of incubation.

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

2019 ◽  
Vol 39 (1) ◽  
pp. 139-149 ◽  
Author(s):  
Måns Ullberg ◽  
Volkan Özenci
Keyword(s):  
Blood Culture ◽  
Antimicrobial Susceptibility ◽  
Susceptibility Testing ◽  
Bloodstream Infections ◽  
Blood Cultures ◽  
Antimicrobial Susceptibility Testing ◽  
Gram Negative Bacteria ◽  
Gram Positive ◽  
Gram Negative ◽  
Hands On

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 piperacillin-tazobactam 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.

scholarly journals 663. Improved Detection of ESBL and AmpC Beta-Lactamase Producing Isolates of Enterobacteriaceae in Pediatric Patients with Bloodstream Infections Using Combined Genotypic and Phenotypic Antimicrobial Susceptibility Testing

2020 ◽  
Vol 7 (Supplement_1) ◽  
pp. S387-S387
Author(s):  
Nadim Khalil ◽  
Eleanor Powell ◽  
Joel Mortensen
Keyword(s):  
Antimicrobial Susceptibility ◽  
Pediatric Patients ◽  
Susceptibility Testing ◽  
Pediatric Population ◽  
Bloodstream Infections ◽  
Blood Cultures ◽  
Antimicrobial Susceptibility Testing ◽  
Molecular Testing ◽  
E Coli ◽  
First Time

Abstract Background Infections secondary to pathogens resistant to third-generation cephalosporins (3GC), such as extended-spectrum (ESBL) and AmpC β-lactamase (AmpC) producing Enterobacteriaceae, are increasing. Currently, there are no recommendations regarding identification of AmpC in Citrobacter, Enterobacter, Morganella and Serratia spp. (CEMS organisms). This study’s aim was to increase the detection of AmpC and ESBL producing Enterobacteriaceae in blood cultures from pediatric population by combining genotypic with phenotypic antimicrobial susceptibility testing (AST). Methods All first time Enterobacteriaceae isolates recovered from blood cultures of pediatric patients at CCHMC between January 2017 and December 2018 were evaluated. The Check-MDR CT103XL assay was used to determine the presence of AmpC and ESBL. AST was performed using the Vitek 2 platform. Phenotypic ESBL resistance was defined by resistant to either ceftriaxone of ceftazidime using CLSI breakpoints. Combined cefoxitin resistance with ceftriaxone or ceftazidime resistance was used to define phenotypic AmpC (EUCAST standards). Results There were 170 isolates, from 147 patients, with 21 (12.4%) AmpC and 18 (10.6%) ESBL genes detected. Using AST, 11 (6.5%) and 26 (15.3%) isolates met AmpC and ESBL phenotypic criteria respectively. However, 14 of the isolates with AmpC genes detected and 2 of isolates with ESBL genes detected failed to meet phenotypic criteria. In addition, 4 (19%) of 21 AmpC isolates were susceptible to cefoxitin and 3GC while both E. coli and S. marcescens genotypic ESBL isolates were susceptible to 3GC. Number of AmpC- and ESBL- Producing Isolates Detected Using Phenotypic Method a,b, Genotypic Method and Combined Testing Conclusion We identified 16 (9.4%) isolates with resistance genes detected but that failed to meet phenotypic criteria. Without molecular testing, patients with these isolates may have been treated with 3GC which could have resulted in treatment failure. The addition of genotypic testing to AST improved the identification of AmpC and ESBL organisms and provided clinically relevant data to guide treatment of resistant organisms. Combined testing is also beneficial for infection control and epidemiological purposes. Disclosures All Authors: No reported disclosures

scholarly journals Integrating Bacterial Identification and Susceptibility Testing: A Simple and Rapid Approach to Reduce the Turnaround Time in the Management of Blood Cultures

2019 ◽  
Vol 2019 ◽  
pp. 1-6
Author(s):  
Dariane C. Pereira ◽  
Luciano Z. Goldani
Keyword(s):  
Antimicrobial Susceptibility ◽  
Susceptibility Testing ◽  
Bloodstream Infections ◽  
Turnaround Time ◽  
Blood Cultures ◽  
Antimicrobial Susceptibility Testing ◽  
Bacterial Identification ◽  
Current Standard ◽  
Short Period ◽  
Infection Diagnostics

We evaluated a rapid bacterial identification (rID) and a rapid antimicrobial susceptibility testing by disk diffusion (rAST) from positive blood culture to overcome the limitations of the conventional methods and reduce the turnaround time in bloodstream infection diagnostics. The study included hemocultures flagged as positive by bacT/ALERT®, identification by MALDI-TOF MS, and rAST. The results were compared to identification and antimicrobial susceptibility testing (AST) results by current standard methods, after 24 h incubation. For rAST categorical agreement (CA), very major errors (VME), major errors (ME), and minor errors (mE) were calculated. A total of 524 bacterial samples isolated from blood cultures were obtained, including 246 Gram-negative (GN) and 278 Gram-positive (GP) aerobes. The overall concordance of rID was 88.6%, and it was highest among GN (96%). A total of 2196 and 1476 antimicrobial agent comparisons were obtained for GN and GP, respectively. Evaluation of rAST, CA, VME, ME, and mE disclosed 97.7, 0.7, 0.5, and 1.1% for GN and 98.0, 0.5, 0.7, and 0.8% for GP, respectively. Meropenem CA, VME, and ME were 98.3, 0.5, and 0.5%, respectively; mE was not observed. Oxacillin CA, ME, and mE were 97.4, 1.6, and 0.6%, respectively; VME was not observed. Overall, kappa scores of the results of the comparisons demonstrated the high agreement between rAST and the standard method. Identification and AST of aerobic bacteria from positive blood cultures after a short period of incubation on solid blood agar is a fast and reliable method that may improve the management of bloodstream infections.

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