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Khan S, Das A, Mishra A, Vidyarthi AJ, Nandal M, Yadav H, Roy S, Singh M. Evaluation of three protocols for direct susceptibility testing for Gram-negative rods from flagged positive blood culture bottles. Microbiol Spectr 2024; 12:e0308123. [PMID: 38446069 PMCID: PMC10986540 DOI: 10.1128/spectrum.03081-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2023] [Accepted: 02/22/2024] [Indexed: 03/07/2024] Open
Abstract
Bloodstream infections are associated with high mortality, which can be reduced by targeted antibiotic therapy in the early stages of infection. Direct antibiotic susceptibility testing (AST) from flagged positive blood cultures may facilitate the administration of early effective antimicrobials much before the routine AST. This study aimed to evaluate three different direct AST protocols for Gram-negative rods from flagged positive blood culture broths. Blood culture broths showing Gram-negative rods only were subjected to direct AST by Clinical and Laboratory Standards Institute-recommended direct disk diffusion (protocol A). Additionally, automated AST (protocol B) and Kirby-Bauer disk diffusion (protocol C) were performed with standard inoculum prepared from bacterial pellets obtained by centrifuging blood culture broths in serum separator vials. For comparison, conventional AST of isolates from solid media subculture was also performed with Kirby-Bauer disk diffusion (reference standard) and the automated method. Overall, categorical agreements of protocols A, B, and C were 97.6%, 95.7%, and 95.9%, respectively. Among Enterobacterales, minor error, major error, and very major error rates of protocol B were 3.5%, 0.36%, and 0.43%, respectively, whereas minor error, major error, and very major error rates of protocol C were 3.4%, 0.72%, and 0.21%, respectively, and among non-fermenters, protocol B had a minor error rate of 6.5%, and protocol C had a minor error rate of 4.1% and major error rate of 1.9%. All three direct AST protocols demonstrated excellent categorical agreements with the reference method. Performance of protocols B and C between Enterobacterales and non-fermenters was not statistically different. IMPORTANCE Bloodstream infections are associated with high mortality that can be reduced by targeted antibiotic therapy in the early stages of infection. Direct antibiotic susceptibility testing (AST) from flagged positive blood cultures may facilitate the administration of early effective antimicrobials much before the routine AST. Clinical and Laboratory Standards Institute-recommended direct AST can be performed with a limited number of antibiotic disks only. On the other hand, using an automated system for direct AST will not only allow effective laboratory workflow with reduced turnaround time but also provide the minimum inhibitory concentration values of tested antibiotics. However, using expensive automated systems for direct AST may not be feasible for resource-limited laboratories. Therefore, in this study, we aimed to evaluate the CLSI-recommended method and two other direct AST protocols (one with an automated system and the other with disk diffusion) for Gram-negative rods from flagged positive blood cultures.
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Affiliation(s)
- Salman Khan
- Department of Microbiology, National Cancer Institute, All India Institute of Medical Sciences (Jhajjar-campus), New Delhi, India
| | - Arghya Das
- Department of Microbiology, All India Institute of Medical Sciences, Madurai, India
| | - Anwita Mishra
- Department of Microbiology, Mahamana Pandit Madan Mohan Malviya Cancer Centre and Homi Bhabha Cancer Hospital, Varanasi, India
| | - Ashima Jain Vidyarthi
- Department of Microbiology, National Cancer Institute, All India Institute of Medical Sciences (Jhajjar-campus), New Delhi, India
| | - Mukesh Nandal
- Department of Emergency Medicine, National Cancer Institute, All India Institute of Medical Sciences (Jhajjar-campus), New Delhi, India
| | - Himanshu Yadav
- Department of Microbiology, National Cancer Institute, All India Institute of Medical Sciences (Jhajjar-campus), New Delhi, India
| | - Shayak Roy
- Department of Oncoanaesthesia and Palliative Medicine, National Cancer Institute, All India Institute of Medical Sciences (Jhajjar-campus), New Delhi, India
| | - Mahipal Singh
- Department of Microbiology, National Cancer Institute, All India Institute of Medical Sciences (Jhajjar-campus), New Delhi, India
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Pitruzzello G, Johnson S, Krauss TF. Exploring the fundamental limit of antimicrobial susceptibility by near-single-cell electrical impedance spectroscopy. Biosens Bioelectron 2023; 224:115056. [PMID: 36630745 DOI: 10.1016/j.bios.2022.115056] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2022] [Revised: 12/19/2022] [Accepted: 12/29/2022] [Indexed: 12/31/2022]
Abstract
Many novel susceptibility tests are being developed to tackle the worldwide problem of antimicrobial resistance (AMR). The key driver behind these developments, that is the need to reduce the response time, requires an understanding of which bacterial characteristic needs to be monitored to provide a rapid and ideally universal signature of susceptibility. Many characteristics have already been studied, most notably bacterial growth, metabolism and motility. Here, we consider electrical impedance to directly access bacterial metabolism, which can be considered a fundamental indicator of bacterial viability. By studying the electrical response of individual bacteria to an antibiotic challenge, we detect antimicrobial action close to its biological limit. Specifically, we find that it takes 30-60 min to register significant changes in impedance for clinical concentrations of antibiotics, in line with other rapid indicators. Our findings suggest that 60 min is the fundamental lower limit of response time for a realistic susceptibility test at clinically relevant antibiotic concentrations.
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Affiliation(s)
- Giampaolo Pitruzzello
- School of Physics, Engineering and Technology, University of York, YO10 5DD, York, UK.
| | - Steven Johnson
- School of Physics, Engineering and Technology, University of York, YO10 5DD, York, UK
| | - Thomas F Krauss
- School of Physics, Engineering and Technology, University of York, YO10 5DD, York, UK.
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Brandt M, McCullor K, Harris D, Ratzlaff Z, Thompson E, Pfeifer CM. Direct inoculation method for identification and antimicrobial susceptibility testing using matrix-assisted laser desorption ionization-time of flight mass spectrometry and both the Vitek 2 and MicroScan Walkaway 96 Plus systems. Proc AMIA Symp 2023; 36:354-359. [PMID: 37091762 PMCID: PMC10120532 DOI: 10.1080/08998280.2023.2169556] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/10/2023] Open
Abstract
The aim of our study was to evaluate a protocol utilizing serum separator tubes (SST) to facilitate a faster, cost-effective, direct method for rapid sensitivity testing and identification of positive blood cultures. Spiked cultures were inoculated into either Becton Dickinson (BD) BACTECTM Aerobic Plus or Anaerobic/F bottles containing sterile human blood. Bottles were immediately processed when positive. A parallel study using patient isolates was used in which bacteria were pelleted by SST from positive blood cultures. For identification, a portion of the pellet was tested by matrix-assisted laser desorption/ionization as described by the manufacturer. MicroScan panels and Vitek 2 results were compared. Categorical agreement was used as comparison to standard subculture and/or polymerase chain reaction methods. No discordant identifications were observed, and 86% generated a successful identification when compared to subculture methods. For the Vitek 2, we observed a 99% essential agreement when compared to the subculture method. For the MicroScan Walkaway, we observed 94.9%, 97.4%, and 100% categorical agreement for MIC panels 53, 38, and MICroSTREP Plus 2, respectively. Turnaround times were reduced from 4 hours for identification and 11 hours for antimicrobial sensitivity testing. We conclude that the SST method results in timelier, actionable results for antimicrobial stewardship initiatives.
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Affiliation(s)
- Maryann Brandt
- Microbiology Laboratory, Phoenix Children’s, Phoenix, Arizona
| | - Kimberly McCullor
- Michigan Department of Health and Human Services, Bureau of Laboratories, Lansing, Michigan
| | - Don Harris
- Norman Regional Hospital, Microbiology Laboratory, Norman, Oklahoma
| | - Zachary Ratzlaff
- Norman Regional Hospital, Microbiology Laboratory, Norman, Oklahoma
| | - Eric Thompson
- Norman Regional Hospital, Microbiology Laboratory, Norman, Oklahoma
| | - Cory M. Pfeifer
- Department of Radiology, Phoenix Children’s, Phoenix, Arizona
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Arana DM, Hernández-Hermida Y, Cacho-Calvo J. A simple double differential centrifugation-wash procedure to rapidly obtain bacterial identification and direct antimicrobial susceptibility testing from positive blood cultures. ENFERMEDADES INFECCIOSAS Y MICROBIOLOGIA CLINICA (ENGLISH ED.) 2023; 41:225-229. [PMID: 36610834 DOI: 10.1016/j.eimce.2021.10.011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/11/2021] [Accepted: 10/29/2021] [Indexed: 01/07/2023]
Abstract
INTRODUCTION This study proposes a simple and rapid method for both bacterial identification and direct antimicrobial susceptibility testing (AST) by using MALDI-TOF and a double differential centrifugation-wash procedure from positive blood cultures. METHODS Fifty-two positive blood cultures (37 gramnegative bacilli and 15 grampositive cocci) were studied by two methods for identification and AST: a reference method, and the rapid MALDI-TOF method obtaining a purified pellet by using a double differential centrifugation procedure. RESULTS A total of 1101 MIC values (mg/l) were interpreted according to EUCAST clinical breakpoints and compared using the two methods simultaneously. Discrepancies in 81 MIC values (7.35%) were detected. By analyzing standard parameters, we obtained 98.28% essential agreement and 92.65% categorical agreement considering all isolates tested. CONCLUSION This method provides rapid bacterial identification and AST, offering definitive results 24-48h earlier than the conventional method (p<0.001) and improving the turnaround time in blood culture diagnostics, especially in laboratories without 24-h on-call.
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Affiliation(s)
- David M Arana
- Servicio de Microbiología, Hospital Universitario de Getafe, Madrid, Spain.
| | | | - Juana Cacho-Calvo
- Servicio de Microbiología, Hospital Universitario de Getafe, Madrid, Spain
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Filbrun AB, Richardson JC, Khanal PC, Tzeng Y, Dickson RM. Rapid, label‐free antibiotic susceptibility determined directly from positive blood culture. Cytometry A 2022; 101:564-576. [DOI: 10.1002/cyto.a.24560] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2021] [Revised: 03/19/2022] [Accepted: 04/06/2022] [Indexed: 11/12/2022]
Affiliation(s)
- Alexandra B. Filbrun
- School of Chemistry and Biochemistry and Petit Institute of Bioengineering and Bioscience Georgia Institute of Technology Atlanta GA
| | - Joseph C. Richardson
- School of Chemistry and Biochemistry and Petit Institute of Bioengineering and Bioscience Georgia Institute of Technology Atlanta GA
| | - Prakash C. Khanal
- School of Chemistry and Biochemistry and Petit Institute of Bioengineering and Bioscience Georgia Institute of Technology Atlanta GA
| | - Yih‐Ling Tzeng
- Division of Infectious Disease, Department of Medicine Emory University School of Medicine Atlanta GA
| | - Robert M. Dickson
- School of Chemistry and Biochemistry and Petit Institute of Bioengineering and Bioscience Georgia Institute of Technology Atlanta GA
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Arana DM, Hernández-Hermida Y, Cacho-Calvo J. A simple double differential centrifugation-wash procedure to rapidly obtain bacterial identification and direct antimicrobial susceptibility testing from positive blood cultures. Enferm Infecc Microbiol Clin 2021. [DOI: 10.1016/j.eimc.2021.10.016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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Grohs P, Picard S, Mainardi JL, Podglajen I. Assessment of version 2.5 of QMAC-dRAST for rapid antimicrobial susceptibility testing with reduced sample-to-answer turnaround time and an integrated expert system. Infect Dis Now 2021; 51:470-476. [PMID: 34366083 DOI: 10.1016/j.idnow.2020.10.005] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2020] [Accepted: 10/29/2020] [Indexed: 12/14/2022]
Abstract
OBJECTIVE To assess the performance of the new rapid antimicrobial susceptibility testing (AST) QMAC-dRAST V2.5 system. METHODS ASTs were performed using QMAC-dRAST-V2.5 and a disk diffusion method, directly from positive blood bottles with Gram-negative bacteria. Discrepancies between the results obtained using the two methods were categorized into very major errors (VME, S with dRAST vs. R with disk diffusion), major errors (ME, R vs. S, respectively), minor errors (mE, S vs. I or I vs. R, respectively), and very minor errors (Vme, I vs. S or R vs. I, respectively). For each AST, results were recorded after 4, 5, and 6h of incubation. RESULTS From 106 bacteremia, 1416 individual AST results were obtained. Overall agreement between results using the two methods was 91%, ranging from 76.9% to 99.1% depending upon the antibiotic, with 128 errors, i.e. 14/1416 (1%) VME, 59/1416 (4.2%) ME, 25/1416 (1.8%) mE and 30/1416 (2.1%) Vme. VMEs were encountered for Klebsiellasp and Serratia marcescens isolates with low-level piperacillin and amikacin resistance, respectively. Using the integrated QMAC-dRAST-V2.5 expert system, all 14 VMEs and 3 mEs were eliminated, leading to 92.2% categorical agreement. After 45min of pre-incubation in the QMAC-dRAST-V2.5 device, 22.2% of the 1416 AST results were obtained after 4h, an additional 31.4% after 5h and a further 46.3% after 6h. CONCLUSION QMAC-dRAST-V2.5 is an optimized version of QMAC-dRAST V2.0, particularly with respect to utilization of an expert system and reduced TAT according to the antibiotic tested.
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Affiliation(s)
- Patrick Grohs
- Microbiology department, Georges-Pompidou European Hospital, AP-HP, Centre - Université de Paris, Paris, France.
| | - Simon Picard
- Microbiology department, Georges-Pompidou European Hospital, AP-HP, Centre - Université de Paris, Paris, France
| | - Jean-Luc Mainardi
- Microbiology department, Georges-Pompidou European Hospital, AP-HP, Centre - Université de Paris, Paris, France
| | - Isabelle Podglajen
- Microbiology department, Georges-Pompidou European Hospital, AP-HP, Centre - Université de Paris, Paris, France
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Falconer K, Hammond R, Gillespie SH. Improving the recovery and detection of bloodstream pathogens from blood culture. J Med Microbiol 2020; 69:806-811. [PMID: 32490793 PMCID: PMC7451035 DOI: 10.1099/jmm.0.001209] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Introduction. Bloodstream infections (BSI) are growing in incidence and present a serious health threat. Most patients wait up to 48 h before microbiological cultures can confirm a diagnosis. Low numbers of circulating bacteria in patients with BSI mean we need to develop new methods and optimize current methods to facilitate efficient recovery of bacteria from the bloodstream. This will allow detection of positive blood cultures in a more clinically useful timeframe. Many bacterial blood recovery methods are available and usually include a combination of techniques such as centrifugation, filtration, serum separation or lysis treatment. Here, we evaluate nine different bacteria recovery methods performed directly from blood culture. Aim. We sought to identify a bacterial recovery method that would allow for a cost-effective and efficient recovery of common BSI pathogens directly from blood culture. Methods. Simulated E. coli ATCC 25922 blood culture was used as a model system to evaluate nine different bacteria recovery methods. Each method was assessed on recovery yield, cost, hands-on time, risk of contamination and ease of use. The highest scoring recovery method was further evaluated using simulated blood cultures spiked with seven of the most frequently occurring bloodstream pathogens. The recovery yield was calculated based on c.f.u. count before and after each recovery method. Independent t-tests were performed to determine if the recovery methods evaluated were significantly different based on c.f.u. ml−1 log recovery. Results. All nine methods evaluated successfully recovered E. coli ATCC 25922 from simulated blood cultures although the bacterial yield differed significantly. The MALDI-TOF intact cell method offered the poorest recovery with a mean loss of 2.94±0.37 log c.f.u. ml−1. In contrast, a method developed by Bio-Rad achieved the greatest bacterial yield with a mean bacteria loss of 0.27±0.013 log c.f.u. ml−1. Overall, a low-speed serum-separation method was demonstrated to be the most efficient method in terms of time, cost and recovery efficiency and successfully recovered seven of the most frequent BSI pathogens with a mean bacteria loss of 0.717±0.18 log c.f.u. ml−1. Conclusion. The efficiency of bacterial recovery can vary significantly between different methods and thereby can have a critical impact on downstream analysis. The low-speed serum-separation method offered a simple and effective means of recovering common BSI pathogens from blood culture and will be further investigated for use in the rapid detection of bacteraemia and susceptibility testing in clinical practice.
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Affiliation(s)
- Kerry Falconer
- School of Medicine, University of St Andrews, St Andrews, UK
| | - Robert Hammond
- School of Medicine, University of St Andrews, St Andrews, UK
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9
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Ucak Ozkaya G, Durak MZ, Akyar I, Karatuna O. Antimicrobial Susceptibility Test for the Determination of Resistant and Susceptible S. aureus and Enterococcus spp. Using a Multi-Channel Surface Plasmon Resonance Device. Diagnostics (Basel) 2019; 9:E191. [PMID: 31731591 PMCID: PMC6963824 DOI: 10.3390/diagnostics9040191] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2019] [Revised: 11/06/2019] [Accepted: 11/12/2019] [Indexed: 11/17/2022] Open
Abstract
The objective of this study was to investigate the development of a surface plasmon resonance (SPR) sensor platform equipped with multiple channels for the simultaneous determination of methicillin-resistant S. aureus (MRSA), methicillin-susceptible S. aureus (MSSA) and vancomycin-resistant Enterococcus (VRE), and vancomycin-susceptible Enterococcus (VSE). Drug resistance of S. aureus strains against cefoxitin and Enterococcus strains against vancomycin were investigated both using the minimum inhibitory concentration method (MIC) assay and the SPR system equipped with single and multiple channels. The MIC values of MRSA and MSSA ranged from 32 µg/mL to >128 µg/mL and from 1 µg/mL to 4 µg/mL, respectively. The MIC values of VRE and VSE were between 64 to >128 µg/mL and 2-4 µg/mL, respectively. With the multiple-channel system, the angle shifts of MRSA, MSSA, VRE and VSE were found to be -0.030° and -0.260°, -0.010° and -0.090° respectively. The antibiotic-resistant and susceptible strains were distinguished within 3 h for S. aureus strains and within 6 h for Enterococcus strains.
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Affiliation(s)
- Gulsum Ucak Ozkaya
- Department of Food Engineering, Faculty of Chemical and Metallurgical Engineering, Yildiz Technical University, Istanbul 34210, Turkey
- Department of Food Engineering, Faculty of Engineering and Architecture, Bitlis Eren University, Bitlis 13000, Turkey
| | - Muhammed Zeki Durak
- Department of Food Engineering, Faculty of Chemical and Metallurgical Engineering, Yildiz Technical University, Istanbul 34210, Turkey
| | - Isin Akyar
- Department of Medical Microbiology, School of Medicine, Acibadem University, Istanbul 34752, Turkey; (I.A.); (O.K.)
| | - Onur Karatuna
- Department of Medical Microbiology, School of Medicine, Acibadem University, Istanbul 34752, Turkey; (I.A.); (O.K.)
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Cansizoglu MF, Tamer YT, Farid M, Koh AY, Toprak E. Rapid ultrasensitive detection platform for antimicrobial susceptibility testing. PLoS Biol 2019; 17:e3000291. [PMID: 31145726 PMCID: PMC6559665 DOI: 10.1371/journal.pbio.3000291] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2018] [Revised: 06/11/2019] [Accepted: 05/10/2019] [Indexed: 12/16/2022] Open
Abstract
Rapid detection and phenotyping of pathogenic microbes is critical for administration of effective antibiotic therapies and for impeding the spread of antibiotic resistance. Here, we present a novel platform, rapid ultrasensitive detector (RUSD), that utilizes the high reflectance coefficient at high incidence angles when light travels from low- to high-refractive-index media. RUSD leverages a principle that does not require complex manufacturing, labeling, or processing steps. Utilizing RUSD, we can detect extremely low cell densities (optical density [OD] ≥ 5 × 10−7) that correspond to approximately 20 bacterial cells or a single fungal cell in the detection volume, which is nearly 4 orders of magnitude more sensitive than standard OD methods. RUSD can measure minimum inhibitory concentrations (MICs) of commonly used antibiotics against gram-negative and gram-positive bacteria, including Staphylococcus aureus, Pseudomonas aeruginosa, and Escherichia coli, within 2 to 4 h. Here, we demonstrate that antibiotic susceptibility tests for several pathogens can rapidly be performed with RUSD using both small inoculum sizes (500 cells/mL) and larger inoculum sizes (5 × 105 cells/mL) used in standard antibiotic susceptibility tests. We anticipate that the RUSD system will be particularly useful for the cases in which antibiotic susceptibility tests have to be done with a limited number of bacterial cells that are available. Its compatibility with standard antibiotic susceptibility tests, simplicity, and low cost can make RUSD a viable and rapidly deployed diagnostic tool. This article presents a novel diagnostic platform, the rapid ultrasensitive detector (RUSD), able to detect as few as 20 bacterial cells or a single fungal cell, and allowing the rapid measurement of antibiotic susceptibility.
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Affiliation(s)
- Mehmet F. Cansizoglu
- Green Center for Systems Biology, University of Texas Southwestern Medical Center, Dallas, Texas, United States of America
| | - Yusuf Talha Tamer
- Green Center for Systems Biology, University of Texas Southwestern Medical Center, Dallas, Texas, United States of America
| | - Michael Farid
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, Maryland, United States of America
| | - Andrew Y. Koh
- Department of Pediatrics, University of Texas Southwestern Medical Center, Dallas, Texas, United States of America
- Department of Microbiology, University of Texas Southwestern Medical Center, Dallas, Texas, United States of America
| | - Erdal Toprak
- Green Center for Systems Biology, University of Texas Southwestern Medical Center, Dallas, Texas, United States of America
- Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, Texas, United States of America
- * E-mail:
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Höring S, Massarani AS, Löffler B, Rödel J. Rapid antibiotic susceptibility testing in blood culture diagnostics performed by direct inoculation using the VITEK®-2 and BD Phoenix™ platforms. Eur J Clin Microbiol Infect Dis 2019; 38:471-478. [PMID: 30680555 DOI: 10.1007/s10096-018-03445-3] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2018] [Accepted: 11/29/2018] [Indexed: 12/29/2022]
Abstract
Early availability of microbiological results can improve treatment decisions of patients suffering from bloodstream infections. Direct inoculation of automated susceptibility testing (AST) platforms is an approach to shorten time-to-result in blood culture diagnostics. We performed a comparative evaluation of the two commercial AST systems VITEK®-2 and BD Phoenix™ for the direct inoculation with blood culture samples. Furthermore, two different methods of sample preparation were compared in this study. Positive blood cultures were prepared for direct inoculation by use of serum separator tubes and twofold centrifugation. AST was performed with the VITEK®-2 and the BD Phoenix™ system by the standard method according to the manufacturer's recommendations using subcultures on solid media and by direct inoculation of blood culture samples. A hundred clinical samples from blood cultures were included in this study. Rapid AST by direct inoculation showed inter-test agreement rates ranging from 92.45 to 97.7%. Comparing both AST platforms, the VITEK®-2 system demonstrated a higher test accuracy for direct inoculation. No relevant difference was observed for the two different sample preparation methods. Direct inoculation is an easy and inexpensive approach to obtain early full panel phenotypic AST results in blood culture diagnostics. Sample preparation is sufficiently performed by a simple centrifugation method. Both commercial platforms, the VITEK®-2 and the BD Phoenix™, have proven suitable for the use of direct inoculation.
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Affiliation(s)
- Steffen Höring
- Institute of Medical Microbiology, Jena University Hospital, Am Klinikum 1, 07747, Jena, Germany.
| | - Alain Sami Massarani
- Institute of Medical Microbiology, Jena University Hospital, Am Klinikum 1, 07747, Jena, Germany
| | - Bettina Löffler
- Institute of Medical Microbiology, Jena University Hospital, Am Klinikum 1, 07747, Jena, Germany
| | - Jürgen Rödel
- Institute of Medical Microbiology, Jena University Hospital, Am Klinikum 1, 07747, Jena, Germany
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12
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Direct antimicrobial susceptibility testing from positive blood culture bottles in laboratories lacking automated antimicrobial susceptibility testing systems. Med J Armed Forces India 2018; 75:450-457. [PMID: 31719741 DOI: 10.1016/j.mjafi.2018.08.010] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2017] [Accepted: 08/23/2018] [Indexed: 11/20/2022] Open
Abstract
Background Timely initiation of appropriate antimicrobial can improve the outcome in terms of reduced morbidity and mortality in addition to reduced health-care costs. Availability of early preliminary Antimicrobial Susceptibility Test (AST) report will be useful in directing antimicrobial therapy. The aim of the study was to correlate AST by disc diffusion method, directly from positively flagged blood culture bottles, with the AST by automated method. Methods A total of 144 aerobic blood culture bottles flagged positive by the automated blood culture system were processed. The bacteria were pelleted by two-step centrifugation of the broth from the bottle and used to make a smear for Gram stain as well as an inoculum for antimicrobial sensitivity testing by Kirby Bauer disc diffusion method. Automated identification and AST were also carried out. Results On direct staining, 94 samples showed gram-negative bacilli, 39 showed gram-positive cocci, and 11 showed yeasts or polymicrobial growth. In the case of gram-negative bacteria, there was 99% categorical agreement between direct sensitivity testing and automated sensitivity testing with 1% disagreement. Among the gram-positive cocci, there was 96% categorical agreement with 4% disagreement between the two methods. Conclusion High degree of agreement between the two methods is promising and applicable to situations where automated sensitivity testing is not available. Even if the systems are available, this method would prove useful as an adjunct to standard AST reporting. This sensitivity report can be generated earlier than the conventional AST, enabling choice of appropriate antimicrobial.
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Tabak YP, Vankeepuram L, Ye G, Jeffers K, Gupta V, Murray PR. Blood Culture Turnaround Time in U.S. Acute Care Hospitals and Implications for Laboratory Process Optimization. J Clin Microbiol 2018; 56:e00500-18. [PMID: 30135230 PMCID: PMC6258864 DOI: 10.1128/jcm.00500-18] [Citation(s) in RCA: 68] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2018] [Accepted: 08/08/2018] [Indexed: 01/03/2023] Open
Abstract
The rapid identification of blood culture isolates and antimicrobial susceptibility test (AST) results play critical roles for the optimal treatment of patients with bloodstream infections. Whereas others have looked at the time to detection in automated culture systems, we examined the overall time from specimen collection to actionable test results. We examined four points of time, namely, blood specimen collection, Gram stain, organism identification (ID), and AST reports, from electronic data from 13 U.S. hospitals for the 11 most common, clinically significant organisms in septic patients. We compared the differences in turnaround times and the times from when specimens were collected and the results were reported in the 24-h spectrum. From January 2015 to June 2016, 165,593 blood specimens were collected, of which, 9.5% gave positive cultures. No matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) mass spectrometry was used during the study period. Across the 10 common bacterial isolates (n = 6,412), the overall median (interquartile range) turnaround times were 0.80 (0.64 to 1.08), 1.81 (1.34 to 2.46), and 2.71 (2.46 to 2.99) days for Gram stain, organism ID, and AST, respectively. For all positive cultures, approximately 25% of the specimens were collected between 6:00 a.m. and 11:59 a.m. In contrast, more of the laboratory reporting times were concentrated between 6:00 a.m. and 11:59 a.m. for Gram stain (43%), organism ID (78%), and AST (82%), respectively (P < 0.001). The overall average turnaround times from specimen collection for Gram stain, organism ID, and AST were approximately 1, 2, and 3 days, respectively. The laboratory results were reported predominantly in the morning hours. Laboratory automation and work flow optimization may play important roles in reducing the microbiology result turnaround time.
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Affiliation(s)
- Ying P Tabak
- Becton, Dickenson and Co., Medical Affairs, Franklin Lakes, New Jersey, USA
| | - Latha Vankeepuram
- Becton, Dickenson and Co., Medical Affairs, Franklin Lakes, New Jersey, USA
| | - Gang Ye
- Becton, Dickenson and Co., Medical Affairs, Franklin Lakes, New Jersey, USA
| | - Kay Jeffers
- Becton, Dickenson and Co., Technology Solution, San Diego, California, USA
| | - Vikas Gupta
- Becton, Dickenson and Co., Digital Health, Franklin Lakes, New Jersey, USA
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Florio W, Tavanti A, Barnini S, Ghelardi E, Lupetti A. Recent Advances and Ongoing Challenges in the Diagnosis of Microbial Infections by MALDI-TOF Mass Spectrometry. Front Microbiol 2018; 9:1097. [PMID: 29896172 PMCID: PMC5986882 DOI: 10.3389/fmicb.2018.01097] [Citation(s) in RCA: 60] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2017] [Accepted: 05/08/2018] [Indexed: 12/25/2022] Open
Abstract
Timeliness and accuracy in the diagnosis of microbial infections are associated with decreased mortality and reduced length of hospitalization, especially for severe, life-threatening infections. A rapid diagnosis also allows for early streamlining of empirical antimicrobial therapies, thus contributing to limit the emergence and spread of antimicrobial resistance. The introduction of matrix-assisted laser desorption/ionization-time of flight (MALDI-TOF) mass spectrometry (MS) for routine identification of microbial pathogens has profoundly influenced microbiological diagnostics, and is progressively replacing biochemical identification methods. Compared to currently used identification methods, MALDI-TOF MS has the advantage of identifying bacteria and yeasts directly from colonies grown on culture plates for primary isolation in a few minutes and with considerable material and labor savings. The reliability and accuracy of MALDI-TOF MS in identification of clinically relevant bacteria and yeasts has been demonstrated by several studies showing that the performance of MALDI-TOF MS is comparable or superior to phenotypic methods currently in use in clinical microbiology laboratories, and can be further improved by database updates and analysis software upgrades. Besides microbial identification from isolated colonies, new perspectives are being explored for MALDI-TOF MS, such as identification of pathogens directly from positive blood cultures, sub-species typing, and detection of drug resistance determinants. In this review, we summarize the state of the art in routine identification of microbial pathogens by MALDI-TOF MS, and highlight recent advancements of this technology in special applications, such as strain typing, assessment of drug susceptibility, and detection of virulence factors.
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Affiliation(s)
- Walter Florio
- Dipartimento di Ricerca Traslazionale e delle Nuove Tecnologie in Medicina e Chirurgia, Università di Pisa, Pisa, Italy
| | | | | | - Emilia Ghelardi
- Dipartimento di Ricerca Traslazionale e delle Nuove Tecnologie in Medicina e Chirurgia, Università di Pisa, Pisa, Italy
| | - Antonella Lupetti
- Dipartimento di Ricerca Traslazionale e delle Nuove Tecnologie in Medicina e Chirurgia, Università di Pisa, Pisa, Italy
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Lemos TC, Cogo LL, Maestri AC, Hadad M, Nogueira KDS. Is it possible to perform bacterial identification and antimicrobial susceptibility testing with a positive blood culture bottle for quick diagnosis of bloodstream infections? Rev Soc Bras Med Trop 2018; 51:215-218. [PMID: 29768557 DOI: 10.1590/0037-8682-0311-2017] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2017] [Accepted: 10/10/2017] [Indexed: 11/22/2022] Open
Abstract
INTRODUCTION Bloodstream infections can be fatal, and timely identification of the etiologic agent is important for treatment. METHODOLOGY An alternative method, consisting of direct identification and susceptibility testing of blood culture bottles using the automated VITEK 2® system, was assessed. RESULTS All 37 of the Gram-negative bacilli (GNB) identifications and 57.1% of the 28 Gram-positive cocci (GPC) identifications matched those obtained with standard methods. In susceptibility testing, the agreement was greater than 90%. CONCLUSIONS This alternative methodology may assist in the early identification and susceptibility testing of GNB. Further research is necessary to develop appropriate methods for GPC.
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Affiliation(s)
- Tamily Cristina Lemos
- Residência Multiprofissional em Atenção Hospitalar, Universidade Federal do Paraná, Curitiba, PR, Brasil
| | - Laura Lúcia Cogo
- Hospital de Clínicas da Universidade Federal do Paraná, Curitiba, PR, Brasil
| | | | - Milena Hadad
- BioMérieux SA, Jacarepaguá, Rio de Janeiro, RJ, Brasil
| | - Keite da Silva Nogueira
- Hospital de Clínicas da Universidade Federal do Paraná, Curitiba, PR, Brasil.,Departamento de Patologia Básica, Universidade Federal do Paraná, Curitiba, PR, Brasil
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Pan HW, Li W, Li RG, Li Y, Zhang Y, Sun EH. Simple Sample Preparation Method for Direct Microbial Identification and Susceptibility Testing From Positive Blood Cultures. Front Microbiol 2018; 9:481. [PMID: 29616003 PMCID: PMC5869256 DOI: 10.3389/fmicb.2018.00481] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2017] [Accepted: 02/28/2018] [Indexed: 11/13/2022] Open
Abstract
Rapid identification and determination of the antibiotic susceptibility profiles of the infectious agents in patients with bloodstream infections are critical steps in choosing an effective targeted antibiotic for treatment. However, there has been minimal effort focused on developing combined methods for the simultaneous direct identification and antibiotic susceptibility determination of bacteria in positive blood cultures. In this study, we constructed a lysis-centrifugation-wash procedure to prepare a bacterial pellet from positive blood cultures, which can be used directly for identification by matrix-assisted laser desorption/ionization-time-of-flight mass spectrometry (MALDI-TOF MS) and antibiotic susceptibility testing by the Vitek 2 system. The method was evaluated using a total of 129 clinical bacteria-positive blood cultures. The whole sample preparation process could be completed in <15 min. The correct rate of direct MALDI-TOF MS identification was 96.49% for gram-negative bacteria and 97.22% for gram-positive bacteria. Vitek 2 antimicrobial susceptibility testing of gram-negative bacteria showed an agreement rate of antimicrobial categories of 96.89% with a minor error, major error, and very major error rate of 2.63, 0.24, and 0.24%, respectively. Category agreement of antimicrobials against gram-positive bacteria was 92.81%, with a minor error, major error, and very major error rate of 4.51, 1.22, and 1.46%, respectively. These results indicated that our direct antibiotic susceptibility analysis method worked well compared to the conventional culture-dependent laboratory method. Overall, this fast, easy, and accurate method can facilitate the direct identification and antibiotic susceptibility testing of bacteria in positive blood cultures.
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Affiliation(s)
- Hong-Wei Pan
- Department of Clinical Laboratory, Qilu Hospital of Shandong University, Jinan, China
| | - Wei Li
- Department of Clinical Laboratory, Qilu Hospital of Shandong University, Jinan, China
| | - Rong-Guo Li
- Department of Clinical Laboratory, Jinan Maternal and Child Care Hospital, Jinan, China
| | - Yong Li
- Department of Clinical Laboratory, Qilu Hospital of Shandong University, Jinan, China
| | - Yi Zhang
- Department of Clinical Laboratory, Qilu Hospital of Shandong University, Jinan, China
| | - En-Hua Sun
- Department of Clinical Laboratory, Qilu Hospital of Shandong University, Jinan, China
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Florio W, Morici P, Ghelardi E, Barnini S, Lupetti A. Recent advances in the microbiological diagnosis of bloodstream infections. Crit Rev Microbiol 2017; 44:351-370. [PMID: 29185372 DOI: 10.1080/1040841x.2017.1407745] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Rapid identification (ID) and antimicrobial susceptibility testing (AST) of the causative agent(s) of bloodstream infections (BSIs) are essential for the prompt administration of an effective antimicrobial therapy, which can result in clinical and financial benefits. Immediately after blood sampling, empirical antimicrobial therapy, chosen on clinical and epidemiological data, is administered. When ID and AST results are available, the clinician decides whether to continue or streamline the antimicrobial therapy, based on the results of the in vitro antimicrobial susceptibility profile of the pathogen. The aim of the present study is to review and discuss the experimental data, advantages, and drawbacks of recently developed technological advances of culture-based and molecular methods for the diagnosis of BSI (including mass spectrometry, magnetic resonance, PCR-based methods, direct inoculation methods, and peptide nucleic acid fluorescence in situ hybridization), the understanding of which could provide new perspectives to improve and fasten the diagnosis and treatment of septic patients. Although blood culture remains the gold standard to diagnose BSIs, newly developed methods can significantly shorten the turnaround time of reliable microbial ID and AST, thus substantially improving the diagnostic yield.
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Affiliation(s)
- Walter Florio
- a Dipartimento di Ricerca Traslazionale e delle Nuove Tecnologie in Medicina e Chirurgia , Università di Pisa , Pisa , Italy
| | - Paola Morici
- a Dipartimento di Ricerca Traslazionale e delle Nuove Tecnologie in Medicina e Chirurgia , Università di Pisa , Pisa , Italy
| | - Emilia Ghelardi
- a Dipartimento di Ricerca Traslazionale e delle Nuove Tecnologie in Medicina e Chirurgia , Università di Pisa , Pisa , Italy
| | - Simona Barnini
- b U.O. Microbiologia Universitaria Azienda Ospedaliero-Universitaria Pisana , Pisa , Italy
| | - Antonella Lupetti
- a Dipartimento di Ricerca Traslazionale e delle Nuove Tecnologie in Medicina e Chirurgia , Università di Pisa , Pisa , Italy
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Update in Bloodstream Infection Diagnosis Using New Methods in Microbiology. CURRENT TREATMENT OPTIONS IN INFECTIOUS DISEASES 2017. [DOI: 10.1007/s40506-017-0104-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
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Intra J, Sala M, Falbo R, Cappellini F, Brambilla P. Reducing time to identification of aerobic bacteria and fastidious micro-organisms in positive blood cultures. Lett Appl Microbiol 2016; 63:400-405. [DOI: 10.1111/lam.12682] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2016] [Revised: 09/25/2016] [Accepted: 09/28/2016] [Indexed: 12/15/2022]
Affiliation(s)
- J. Intra
- Department of Laboratory Medicine; Desio Hospital; University Milano Bicocca; Desio Italy
| | - M.R. Sala
- Department of Laboratory Medicine; Desio Hospital; University Milano Bicocca; Desio Italy
| | - R. Falbo
- Department of Laboratory Medicine; Desio Hospital; University Milano Bicocca; Desio Italy
| | - F. Cappellini
- Department of Laboratory Medicine; Desio Hospital; University Milano Bicocca; Desio Italy
| | - P. Brambilla
- Department of Laboratory Medicine; Desio Hospital; University Milano Bicocca; Desio Italy
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20
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Barnini S, Brucculeri V, Morici P, Ghelardi E, Florio W, Lupetti A. A new rapid method for direct antimicrobial susceptibility testing of bacteria from positive blood cultures. BMC Microbiol 2016; 16:185. [PMID: 27520338 PMCID: PMC4982226 DOI: 10.1186/s12866-016-0805-5] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2016] [Accepted: 08/04/2016] [Indexed: 11/29/2022] Open
Abstract
Background Rapid identification and antimicrobial susceptibility testing (AST) of the causative agent(s) of bloodstream infections can lead to prompt appropriate antimicrobial therapy. To shorten species identification, in this study bacteria were recovered from monomicrobial blood cultures by serum separator tubes and spotted onto the target plate for direct MALDI-TOF MS identification. Proper antibiotics were selected for direct AST based on species identification. In order to obtain rapid AST results, bacteria were recovered from positive blood cultures by two different protocols: by serum separator tubes (further referred to as PR1), or after a short-term subculture in liquid medium (further referred to as PR2). The results were compared with those obtained by the method currently used in our laboratory consisting in identification by MALDI-TOF and AST by Vitek 2 or Sensititre on isolated colonies. Results The direct MALDI-TOF method concordantly identified with the current method 97.5 % of the Gram-negative bacteria and 96.1 % of the Gram-positive cocci contained in monomicrobial blood cultures. The direct AST by PR1 and PR2 for all isolate/antimicrobial agent combinations was concordant/correct with the current method for 87.8 and 90.5 % of Gram-negative bacteria and for 93.1 and 93.8 % of Gram-positive cocci, respectively. In particular, 100 % categorical agreement was found with levofloxacin for Enterobacteriaceae by both PR1 and PR2, and 99.0 and 100 % categorical agreement was observed with linezolid for Gram-positive cocci by PR1 and PR2, respectively. There was no significant difference in accuracy between PR1 and PR2 for Gram-negative bacteria and Gram-positive cocci. Conclusions This newly described method seems promising for providing accurate AST results. Most importantly, these results would be available in a few hours from blood culture positivity, which would help clinicians to promptly confirm or streamline an effective antibiotic therapy in patients with bloodstream infections. Electronic supplementary material The online version of this article (doi:10.1186/s12866-016-0805-5) contains supplementary material, which is available to authorized users.
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Affiliation(s)
| | | | - Paola Morici
- Dipartimento di Ricerca Traslazionale e delle Nuove Tecnologie in Medicina e Chirurgia, Università di Pisa, Pisa, Italy
| | - Emilia Ghelardi
- Dipartimento di Ricerca Traslazionale e delle Nuove Tecnologie in Medicina e Chirurgia, Università di Pisa, Pisa, Italy
| | - Walter Florio
- Dipartimento di Ricerca Traslazionale e delle Nuove Tecnologie in Medicina e Chirurgia, Università di Pisa, Pisa, Italy
| | - Antonella Lupetti
- Dipartimento di Ricerca Traslazionale e delle Nuove Tecnologie in Medicina e Chirurgia, Università di Pisa, Pisa, Italy.
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Fitzgerald C, Stapleton P, Phelan E, Mulhare P, Carey B, Hickey M, Lynch B, Doyle M. Rapid identification and antimicrobial susceptibility testing of positive blood cultures using MALDI-TOF MS and a modification of the standardised disc diffusion test: a pilot study. J Clin Pathol 2016; 69:jclinpath-2015-203436. [PMID: 27122186 DOI: 10.1136/jclinpath-2015-203436] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2015] [Accepted: 03/31/2016] [Indexed: 11/04/2022]
Abstract
AIMS In an era when clinical microbiology laboratories are under increasing financial pressure, there is a need for inexpensive, yet effective, rapid microbiology tests. The aim of this study was to evaluate a novel modification of standard methodology for the identification and antimicrobial susceptibility testing (AST) of pathogens in positive blood cultures, reducing the turnaround time of laboratory results by 24 h. METHODS 277 positive blood cultures had a Gram stain performed and were subcultured and incubated at 37°C in a CO2 atmosphere for 4-6 h. Identification of the visible growth was performed using matrix-assisted laser desorption time of flight mass spectrometry (MALDI-TOF MS). Taking a modified approach to the Clinical and Laboratory Standards Institute-standardised AST methodology, an inoculum density of 0.5 McFarland was prepared from the early growth for disc diffusion testing. The standard AST method was also performed on the 18-24 h culture. RESULTS 96% (n=73/76) of gram-negative organisms were correctly identified by MALDI-TOF MS. Comparative analysis of the rapid and standard AST results showed an overall interpretive category error rate of 7.7% (6.7% minor errors, 0.6% major errors and 0.4% very major errors). 100% of Staphylococcus aureus (n=41) and enterococcus isolates (n=9) were correctly identified after 4-6 h incubation. The overall AST categorical agreement was also 100% for these isolates. CONCLUSIONS An incubation of 4-6 h directly from positive blood cultures allowed for both a rapid species identification and an antimicrobial susceptibility result approximately 24 h earlier than is possible using standard methodology.
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Affiliation(s)
- C Fitzgerald
- Microbiology Laboratory, University Hospital Waterford, Waterford, Ireland
| | - P Stapleton
- Microbiology Laboratory, University Hospital Waterford, Waterford, Ireland
| | - E Phelan
- Microbiology Laboratory, University Hospital Waterford, Waterford, Ireland
| | - P Mulhare
- Microbiology Laboratory, University Hospital Waterford, Waterford, Ireland
| | - B Carey
- Microbiology Laboratory, University Hospital Waterford, Waterford, Ireland
| | - M Hickey
- Microbiology Laboratory, University Hospital Waterford, Waterford, Ireland
| | - B Lynch
- Microbiology Laboratory, University Hospital Waterford, Waterford, Ireland
| | - M Doyle
- Microbiology Laboratory, University Hospital Waterford, Waterford, Ireland
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Schifman RB, Meier FA, Souers RJ. Timeliness and accuracy of reporting preliminary blood culture results: a College of American Pathologists Q-probes study of 65 institutions. Arch Pathol Lab Med 2015; 139:621-6. [PMID: 25927146 DOI: 10.5858/arpa.2014-0258-cp] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
CONTEXT The speed and accuracy of preliminary blood culture reports impacts patient management and outcomes. OBJECTIVE To evaluate the accuracy and timeliness of preliminary blood culture results among multiple laboratories. DESIGN Q-Probes participants collected turnaround time (TAT) data on preliminary Gram stains, compared accuracy of up to 100 preliminary to final culture Gram stain results, and described blood culture laboratory practices. RESULTS Sixty-four laboratories and 5031 blood cultures were evaluated. All participants used continuously monitoring blood culture systems. Median TAT from initial growth detection to notification of results was 45 minutes, with the longest component being preparation of Gram stains (median time = 25 minutes). Participants (N = 40) reporting a continuous schedule for processing blood cultures had significantly lower overall TAT (median= 37 minutes) compared with 15 participants with intermittent processing schedules (median= 124 minutes), P= .003. Time to complete Gram stain processing was lower (median time = 21 minutes) for 39 participants using continuous processing schedule compared with 14 others (median time= 67 minutes), P= .03. Goals for total TAT were used by 27 of 56 participants (48.2%). Having goals did not significantly affect TAT. A total of 4962 of 5021 Gram stain results (98.8%) agreed with final culture results. The highest discrepancy rates occurred among gram-positive bacilli (20 of 335; 6.0%) and mixed cultures (22 of 106; 20.8%). CONCLUSIONS This study provides benchmarks for assessing blood culture quality performance. Timeliness and accuracy of preliminary blood culture reports were excellent. However, nearly one-third of laboratories did not process blood cultures continuously. This significantly prolonged reporting results, which could affect patient outcomes.
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Affiliation(s)
- Ron B Schifman
- From Diagnostics, Southern Arizona VA Healthcare System, University of Arizona College of Medicine, Tucson (Dr Schifman); the Department of Pathology, Massachusetts General Hospital, Boston (Dr Meier); and the Department of Biostatistics, College of American Pathologists, Northfield, Illinois (Ms Souers)
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Barnini S, Ghelardi E, Brucculeri V, Morici P, Lupetti A. Rapid and reliable identification of Gram-negative bacteria and Gram-positive cocci by deposition of bacteria harvested from blood cultures onto the MALDI-TOF plate. BMC Microbiol 2015; 15:124. [PMID: 26084329 PMCID: PMC4471905 DOI: 10.1186/s12866-015-0459-8] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2015] [Accepted: 06/01/2015] [Indexed: 01/14/2023] Open
Abstract
Background Rapid identification of the causative agent(s) of bloodstream infections using the matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) methodology can lead to increased empirical antimicrobial therapy appropriateness. Herein, we aimed at establishing an easier and simpler method, further referred to as the direct method, using bacteria harvested by serum separator tubes from positive blood cultures and placed onto the polished steel target plate for rapid identification by MALDI-TOF. The results by the direct method were compared with those obtained by MALDI-TOF on bacteria isolated on solid media. Results Identification of Gram-negative bacilli was 100 % concordant using the direct method or MALDI-TOF on isolated bacteria (96 % with score > 2.0). These two methods were 90 % concordant on Gram-positive cocci (32 % with score > 2.0). Identification by the SepsiTyper method of Gram-positive cocci gave concordant results with MALDI-TOF on isolated bacteria in 87 % of cases (37 % with score > 2.0). Conclusions The direct method herein developed allows rapid identification (within 30 min) of Gram-negative bacteria and Gram-positive cocci from positive blood cultures and can be used to rapidly report reliable and accurate results, without requiring skilled personnel or the use of expensive kits.
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Affiliation(s)
- Simona Barnini
- Dipartimento di Ricerca Traslazionale e delle Nuove Tecnologie in Medicina e Chirurgia, Università di Pisa, Via San Zeno 35-39, 56127, Pisa, Italy.
| | - Emilia Ghelardi
- Dipartimento di Ricerca Traslazionale e delle Nuove Tecnologie in Medicina e Chirurgia, Università di Pisa, Via San Zeno 35-39, 56127, Pisa, Italy.
| | - Veronica Brucculeri
- Dipartimento di Ricerca Traslazionale e delle Nuove Tecnologie in Medicina e Chirurgia, Università di Pisa, Via San Zeno 35-39, 56127, Pisa, Italy.
| | - Paola Morici
- Dipartimento di Ricerca Traslazionale e delle Nuove Tecnologie in Medicina e Chirurgia, Università di Pisa, Via San Zeno 35-39, 56127, Pisa, Italy.
| | - Antonella Lupetti
- Dipartimento di Ricerca Traslazionale e delle Nuove Tecnologie in Medicina e Chirurgia, Università di Pisa, Via San Zeno 35-39, 56127, Pisa, Italy.
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Survey of physicians' perspectives and knowledge about diagnostic tests for bloodstream infections. PLoS One 2015; 10:e0121493. [PMID: 25811910 PMCID: PMC4374856 DOI: 10.1371/journal.pone.0121493] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2014] [Accepted: 02/01/2015] [Indexed: 11/29/2022] Open
Abstract
Background Physicians rely on blood culture to diagnose bloodstream infections (BSI) despite its limitations. As new technologies emerge for rapid BSI diagnosis, optimization of their application to patient care requires an understanding of clinicians’ perspectives on BSI diagnosis and how a rapid test would influence medical decisions. Methods We administered a 26-question survey to practitioners in infectious diseases/microbiology, critical care, internal medicine, and hematology/oncology services in USA and Germany about current standards in diagnosing and treating BSI and a hypothetical rapid BSI test. Results Responses from 242 providers had roughly equal representation across specialties. For suspected BSI patients, 78% of practitioners would administer empiric broad spectrum antibiotics although they estimated, on average, that 31% of patients received incorrect antibiotics while awaiting blood culture results. The ability of blood culture to rule in or rule out infection was very/extremely acceptable in 67% and 36%, respectively. Given rapid test results, 60–87% of practitioners would narrow the spectrum of antimicrobial therapy depending on the microorganism detected, with significantly higher percentages when resistance determinants were also tested. Over half of respondents felt a rapid test would be very/extremely influential on clinical practice. Conclusions Limitations of blood culture were perceived as a barrier to patient care. A rapid test to diagnose BSI would impact clinical practice, but the extent of impact may be limited by prevailing attitudes and practices. Opportunities exist for interventions to influence practitioners’ behaviors in BSI management particularly with emergence of newer diagnostic tests.
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Stokkou S, Geginat G, Schlüter D, Tammer I. Direct disk diffusion test using European Clinical Antimicrobial Susceptibility Testing breakpoints provides reliable results compared with the standard method. Eur J Microbiol Immunol (Bp) 2015; 5:103-11. [PMID: 25883798 DOI: 10.1556/eujmi-d-15-00005] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2015] [Accepted: 02/01/2015] [Indexed: 11/19/2022] Open
Abstract
Sepsis represents a life-threatening infection requiring the immediate start of antibacterial treatment to reduce morbidity. Thus, laboratories use direct antimicrobial susceptibility testing (AST) to rapidly generate preliminary results from positive blood cultures. As the direct AST has not yet been published to be evaluated with EUCAST breakpoints, the purpose of the study was to investigate the reliability of the direct agar diffusion test to correctly produce AST results from positive monobacterial blood cultures compared with the VITEK2-based definitive AST, when current EUCAST breakpoints were used. A total of 428 isolates from unselected monobacterial routine blood cultures and 110 challenge strains were included. Direct agar diffusion-based and standard VITEK2-based AST of 2803 bacterium-drug combinations yielded a total clinical category agreement of 95.47% with 1.28% very major errors and 3.42% combined major and minor errors. On the species level, very major errors were observed in the species-drug combinations Enterococcus spp.-high-level gentamicin (10.87%) and Staphylococcus spp.-rifampicin (5%), only. No very major errors occurred with Enterobacteriaceae and Pseudomonas aeruginosa. In most species-drug combinations, the direct agar diffusion test using EUCAST breakpoints precisely predicted the result of the definitive antibiotic susceptibility test and, thus, it can be used to optimize empiric antibiotic therapy until definitive results are available.
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Florio W, Barnini S, Morici P, Lupetti A. Direct inoculation of positive blood cultures using the Phoenix system for antimicrobial susceptibility testing of both Gram-positive and Gram-negative bacteria. J Med Microbiol 2015; 64:582-585. [PMID: 25762745 DOI: 10.1099/jmm.0.000053] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2014] [Accepted: 03/09/2015] [Indexed: 11/18/2022] Open
Affiliation(s)
- Walter Florio
- Dipartimento di Ricerca Traslazionale e delle Nuove Tecnologie in Medicina e Chirurgia, Università di Pisa, Pisa, Italy
| | - Simona Barnini
- Dipartimento di Ricerca Traslazionale e delle Nuove Tecnologie in Medicina e Chirurgia, Università di Pisa, Pisa, Italy
| | - Paola Morici
- Dipartimento di Ricerca Traslazionale e delle Nuove Tecnologie in Medicina e Chirurgia, Università di Pisa, Pisa, Italy
| | - Antonella Lupetti
- Dipartimento di Ricerca Traslazionale e delle Nuove Tecnologie in Medicina e Chirurgia, Università di Pisa, Pisa, Italy
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Furlaneto-Maia L, Rocha KR, Siqueira VLD, Furlaneto MC. Comparison between automated system and PCR-based method for identification and antimicrobial susceptibility profile of clinical Enterococcus spp. Rev Inst Med Trop Sao Paulo 2014; 56:97-103. [PMID: 24626409 PMCID: PMC4085851 DOI: 10.1590/s0036-46652014000200002] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2012] [Accepted: 09/05/2013] [Indexed: 11/22/2022] Open
Abstract
Enterococci are increasingly responsible for nosocomial infections
worldwide. This study was undertaken to compare the identification and
susceptibility profile using an automated MicrosScan system, PCR-based assay and
disk diffusion assay of Enterococcus spp. We evaluated 30
clinical isolates of Enterococcus spp. Isolates were identified
by MicrosScan system and PCR-based assay. The detection of antibiotic resistance
genes (vancomycin, gentamicin, tetracycline and erythromycin) was also
determined by PCR. Antimicrobial susceptibilities to vancomycin (30 µg),
gentamicin (120 µg), tetracycline (30 µg) and erythromycin (15 µg) were tested
by the automated system and disk diffusion method, and were interpreted
according to the criteria recommended in CLSI guidelines. Concerning
Enterococcus identification the general agreement between
data obtained by the PCR method and by the automatic system was 90.0% (27/30).
For all isolates of E. faecium and E. faecalis
we observed 100% agreement. Resistance frequencies were higher in E.
faecium than E. faecalis. The resistance rates
obtained were higher for erythromycin (86.7%), vancomycin (80.0%), tetracycline
(43.35) and gentamicin (33.3%). The correlation between disk diffusion and
automation revealed an agreement for the majority of the antibiotics with
category agreement rates of > 80%. The PCR-based assay, the
van(A) gene was detected in 100% of vancomycin resistant
enterococci. This assay is simple to conduct and reliable in the identification
of clinically relevant enterococci. The data obtained reinforced the need for an
improvement of the automated system to identify some enterococci.
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Affiliation(s)
- Luciana Furlaneto-Maia
- Technological Federal University of Paraná, Brazil, Technological Federal University of Paraná, Brazil
| | - Kátia Real Rocha
- Department of Microbiology, State University at Londrina, Paraná, Brazil, Department of Microbiology, State University at Londrina, Paraná, Brazil
| | - Vera Lúcia Dias Siqueira
- Department of Clinical Analysis, State University at Maringa, Paraná, Brazil, Department of Clinical Analysis, State University at Maringa, Paraná, Brazil
| | - Márcia Cristina Furlaneto
- Department of Microbiology, State University at Londrina, Paraná, Brazil, Department of Microbiology, State University at Londrina, Paraná, Brazil
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Lupetti A, Barnini S, Dodi C, Menconi M, Favre C, Giagnoni M, Florio W, Nibbering PH, Campa M. New rapid methods cannot replace the current method to diagnose bloodstream infections. J Med Microbiol 2014; 63:767-769. [PMID: 24554742 DOI: 10.1099/jmm.0.069161-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Affiliation(s)
- Antonella Lupetti
- Dipartimento di Ricerca Traslazionale e delle Nuove Tecnologie in Medicina e Chirurgia, Università di Pisa, Via San Zeno 35-39, 56127 Pisa, Italy
| | - Simona Barnini
- Dipartimento di Ricerca Traslazionale e delle Nuove Tecnologie in Medicina e Chirurgia, Università di Pisa, Via San Zeno 35-39, 56127 Pisa, Italy
| | - Carlotta Dodi
- Dipartimento di Ricerca Traslazionale e delle Nuove Tecnologie in Medicina e Chirurgia, Università di Pisa, Via San Zeno 35-39, 56127 Pisa, Italy
| | - Mariacristina Menconi
- U.O. Oncoematologia Pediatrica con Trapianto di Cellule Staminali Ematopoietiche, Azienda Ospedaliero-Universitaria Pisana, Pisa, Italy
| | - Claudio Favre
- U.O. Oncoematologia Pediatrica con Trapianto di Cellule Staminali Ematopoietiche, Azienda Ospedaliero-Universitaria Pisana, Pisa, Italy
| | - Marco Giagnoni
- Grandi Ustioni, Azienda Ospedaliero-Universitaria Pisana, Pisa, Italy
| | - Walter Florio
- Dipartimento di Ricerca Traslazionale e delle Nuove Tecnologie in Medicina e Chirurgia, Università di Pisa, Via San Zeno 35-39, 56127 Pisa, Italy
| | - Peter H Nibbering
- Center for Infectious Diseases, Department of Infectious Diseases, Leiden University Medical Center, Leiden, The Netherlands
| | - Mario Campa
- Dipartimento di Ricerca Traslazionale e delle Nuove Tecnologie in Medicina e Chirurgia, Università di Pisa, Via San Zeno 35-39, 56127 Pisa, Italy
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La Scola B. Intact cell MALDI-TOF mass spectrometry-based approaches for the diagnosis of bloodstream infections. Expert Rev Mol Diagn 2014; 11:287-98. [DOI: 10.1586/erm.11.12] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
- Bernard La Scola
- URMITE, Faculté de Médecine, 27 Boulevard Jean Moulin, 13385 Marseille cedex 5, France
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Pence MA, McElvania TeKippe E, Burnham CAD. Diagnostic Assays for Identification of Microorganisms and Antimicrobial Resistance Determinants Directly from Positive Blood Culture Broth. Clin Lab Med 2013; 33:651-84. [DOI: 10.1016/j.cll.2013.03.010] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Sodowich BI, Zweitzig DR, Riccardello NM, O'Hara SM. Feasibility study demonstrating that enzymatic template generation and amplification can be employed as a novel method for molecular antimicrobial susceptibility testing. BMC Microbiol 2013; 13:191. [PMID: 23941533 PMCID: PMC3766015 DOI: 10.1186/1471-2180-13-191] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2013] [Accepted: 07/25/2013] [Indexed: 11/21/2022] Open
Abstract
Background Antimicrobial Susceptibility Testing (AST) is a methodology in which the sensitivity of a microorganism is determined via its inability to proliferate in the presence of an antimicrobial agent. Results are reported as minimum inhibitory concentrations (MICs). The present study demonstrates that measurement of DNA polymerase activity via Enzymatic Template Generation and Amplification (ETGA) can be used as a novel means of determining the MIC of a microbe to an antibiotic agent much sooner than the current standardized method. Methods Time course analysis of ETGA is presented from bacterial cultures containing antibiotic agents and compared to the end-point results of standard macrobroth method AST. Results MIC determinations from ETGA results at 4, 6, and 22 hours are compared to the MICs from the standard method and the results are shown to be in agreement. Additionally, reliable AST analysis using ETGA can be performed on bacteria harvested directly from spiked blood cultures. Conclusions AST analysis with ETGA is shown to be equivalent to AST analysis using gene-specific qPCR assays against the measured microbe. Future development of this novel method for performing AST in a clinical setting is discussed.
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Affiliation(s)
- Bruce I Sodowich
- Zeus Scientific Incorporated, Research and Development, 200 Evans Way, Branchburg, NJ 08876, USA.
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Saponin promotes rapid identification and antimicrobial susceptibility profiling of Gram-positive and Gram-negative bacteria in blood cultures with the Vitek 2 system. Eur J Clin Microbiol Infect Dis 2012; 32:493-502. [DOI: 10.1007/s10096-012-1762-z] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2012] [Accepted: 10/08/2012] [Indexed: 11/26/2022]
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Nilsen E. Automated identification and susceptibility determination directly from blood cultures facilitates early targeted antibiotic therapy. ACTA ACUST UNITED AC 2012; 44:860-5. [PMID: 22831285 DOI: 10.3109/00365548.2012.689848] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
BACKGROUND The increasing prevalence of antibiotic resistance is challenging established empirical treatments, making early identification and susceptibility determination more important. To avoid time-consuming overnight cultures, a previously published method for the rapid identification and susceptibility testing of blood cultures was instituted at Molde Hospital. The time saved compared to the standard method, and how often the results could have led to a change in the empirical antibiotic treatment compared to Gram stain from cultures, were evaluated. MATERIAL AND METHODS All positive blood cultures with Gram-negative bacilli obtained between March and December 2010 were included in the study (n = 69). Accuracy and turn-around times were compared to those of the standard methods. The empirical antibiotic treatment was recorded when consulting the clinician about the results. RESULTS Correct identification was obtained in 66/69 (95.7%) of the isolates. Correct susceptibility determination was obtained in 758/759 (99.9%) of the tests. Oral reports to the clinician were given on average 11 h 22 min earlier for identification, and 10 h 51 min earlier for susceptibility determination, compared to the standard methods. With optimal handling we could have managed 17 h 26 min and 16 h 14 min, respectively. In 14/69 cases the empirical treatment included no effective or appropriate antibiotics. 7 of these 14 would not have been changed to working antibiotic treatment based on Gram stain alone. CONCLUSION The rapid method was found to be accurate and showed the potential for the initiation of effective antibiotic treatment more than 16 h earlier for 10% of the patients in this small sample.
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Affiliation(s)
- Einar Nilsen
- Laboratory of Medical Microbiology, Molde Hospital, Molde, and Department of Microbiology and Infection Control, University Hospital of North Norway, Tromsø, Norway.
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Strategy for rapid identification and antibiotic susceptibility testing of gram-negative bacteria directly recovered from positive blood cultures using the Bruker MALDI Biotyper and the BD Phoenix system. J Clin Microbiol 2012; 50:2452-4. [PMID: 22518850 DOI: 10.1128/jcm.00409-12] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Decreasing the time to species identification and antibiotic susceptibility determination of strains recovered from patients with bacteremia significantly decreases morbidity and mortality. Herein, we validated a method to identify Gram-negative bacteria directly from positive blood culture medium using the Bruker MALDI Biotyper and to rapidly perform susceptibility testing using the BD Phoenix.
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Direct inoculation method using BacT/ALERT 3D and BD Phoenix System allows rapid and accurate identification and susceptibility testing for both Gram-positive cocci and Gram-negative rods in aerobic blood cultures. Diagn Microbiol Infect Dis 2012; 73:129-34. [PMID: 22494554 DOI: 10.1016/j.diagmicrobio.2012.03.004] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2012] [Revised: 03/08/2012] [Accepted: 03/09/2012] [Indexed: 11/20/2022]
Abstract
This study describes a direct inoculation method using the automated BacT/ALERT 3D and the BD Phoenix System in combination for identification and susceptibility testing of isolates from positive blood cultures. Organism identification and susceptibility results were compared with the conventional method for 211 positive aerobic blood cultures. Of 110 Gram-positive cocci (GPCs), 98 (89.1%) isolates were correctly identified to the species level. Of 101 Gram-negative rods (GNRs), 98 (97.0%) isolates were correctly identified to the species level. The overall categorical agreement in antimicrobial susceptibility testing among the 110 GPCs was 92.7%, with 0.04% very major and 0.7% major error rates. The overall categorical agreement among 78 isolates of enterobacteria and 23 isolates of nonfermenters in GNRs was 99.5% and 91.1%, respectively, with no major errors identified. We conclude that, compared with previously reported direct inoculation methods, our method is superior in identification and susceptibility testing of GPCs.
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Gherardi G, Angeletti S, Panitti M, Pompilio A, Di Bonaventura G, Crea F, Avola A, Fico L, Palazzo C, Sapia GF, Visaggio D, Dicuonzo G. Comparative evaluation of the Vitek-2 Compact and Phoenix systems for rapid identification and antibiotic susceptibility testing directly from blood cultures of Gram-negative and Gram-positive isolates. Diagn Microbiol Infect Dis 2011; 72:20-31. [PMID: 22030102 DOI: 10.1016/j.diagmicrobio.2011.09.015] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2011] [Revised: 09/08/2011] [Accepted: 09/10/2011] [Indexed: 11/30/2022]
Abstract
We performed a comparative evaluation of the Vitek-2 Compact and Phoenix systems for direct identification and antimicrobial susceptibility testing (AST) from positive blood culture bottles in comparison to the standard methods. Overall, 139 monomicrobial blood cultures, comprising 91 Gram-negative and 48 Gram-positive isolates, were studied. Altogether, 100% and 92.3% of the Gram-negative isolates and 75% and 43.75% of the Gram-positive isolates showed concordant identification between the direct and the standard methods with Vitek and Phoenix, respectively. AST categorical agreements of 98.7% and 99% in Gram-negative and of 96.2% and 99.5% in Gram-positive isolates with Vitek and Phoenix, respectively, were observed. In conclusion, direct inoculation procedures for Gram-negative isolates showed an excellent performance with both automated systems, while for identification of Gram-positive isolates they proved to be less reliable, although Vitek provided acceptable results. This approach contributes to reducing the turnaround time to result of blood cultures, with a positive impact on patient care.
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Affiliation(s)
- Giovanni Gherardi
- Centro Integrato di Ricerche, Laboratory of Clinical Microbiology, University Campus Bio-medico, 00128 Rome, Italy.
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Duggal S, Jesaiwal SK, Tandon N, Chugh TD. Direct inoculation on Phoenix panels for identification and antimicrobial susceptibility from positive BACTEC cultures: First study from India. Indian J Med Microbiol 2011; 29:283-7. [DOI: 10.4103/0255-0857.83914] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
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Beuving J, van der Donk CFM, Linssen CFM, Wolffs PFG, Verbon A. Evaluation of direct inoculation of the BD PHOENIX system from positive BACTEC blood cultures for both Gram-positive cocci and Gram-negative rods. BMC Microbiol 2011; 11:156. [PMID: 21718482 PMCID: PMC3224140 DOI: 10.1186/1471-2180-11-156] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2011] [Accepted: 06/30/2011] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Rapid identification (ID) and antibiotic susceptibility testing (AST) of the causative micro-organism of bloodstream infections result in earlier targeting of antibiotic therapy.In order to obtain results of ID and AST up to 24 hours earlier, we evaluated the accuracy of direct inoculation of the Phoenix system from positive blood cultures (BACTEC) by using Serum Separator Tubes to harvest bacteria from positive blood cultures. Results were compared to those of standard Phoenix procedure. Discrepancies between the two methods were resolved by using the API system, E-test or microbroth dilution. RESULTS ID with the direct method was correct for 95.2% of all tested Enterobacteriaceae (n = 42) and 71.4% of Pseudomonas aeruginosa strains (n = 7).AST with the direct method showed a categorical agreement for Gram-negative rods (GNR) of 99.0%, with 0.7% minor errors, 0.3% very major errors and no major errors. All antibiotics showed an agreement of >95%.The direct method for AST of Staphylococcus (n = 81) and Enterococcus (n = 3) species showed a categorical agreement of 95.4%, with a minor error rate of 1.1%, a major error rate of 3.1% and a very major error rate of 0.4%. All antibiotics showed an agreement of >90%, except for trimethoprim-sulfamethoxazole and erythromycin. CONCLUSIONS Inoculation of Phoenix panels directly from positive blood cultures can be used to report reliable results of AST of GNR a day earlier, as well as ID-results of Enterobacteriaceae. For Staphylococcus and Enterococcus species, results of AST can also be reported a day earlier for all antibiotics, except for erythromycin and trimethoprim-sulfamethoxazole.
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Affiliation(s)
- Judith Beuving
- Department of Medical Microbiology, Care And Public Health Research Institute, Maastricht University Medical Center, PO Box 5800, 6202AZ Maastricht, the Netherlands
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Lupetti A, Barnini S, Castagna B, Capria AL, Nibbering PH. Rapid identification and antimicrobial susceptibility profiling of Gram-positive cocci in blood cultures with the Vitek 2 system. Eur J Clin Microbiol Infect Dis 2009; 29:89-95. [PMID: 19902279 PMCID: PMC2797424 DOI: 10.1007/s10096-009-0825-2] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2009] [Accepted: 10/03/2009] [Indexed: 11/08/2022]
Abstract
Rapid identification and antimicrobial susceptibility profiling of the bacteria in blood cultures can result in clinical and financial benefits. Addition of saponin to the fluid from blood culture bottles promotes the recovery of the bacteria and thus may shorten the turnaround time of the microbiological analyses. In this study we compared the identification and susceptibility profiles of saponin-treated and untreated (standard method) blood cultures monomicrobial for Gram-positive cocci using Vitek 2. We concordantly identified 49 (89%) of 55 monobacterial cultures using the results with the standard method as reference. Complete categorical agreement between the susceptibility profiles with the new and the standard method was found for 26 (53%) of 49 isolates, while discrepancies were seen for 23 (47%) cultures. E-tests indicated that the new method resulted in a correct susceptibility profile for 8 (35%) of these 23 blood cultures. Therefore, 34 (69%) of 49 cultures showed a concordant/correct susceptibility profile for all antimicrobials with an overall error rate of 2.3%. Thus, addition of saponin to the fluid from blood culture bottles of the Bactec 9240 leads to the rapid (results available ≥12 hours earlier) and reliable identification and susceptibility profiling of Gram-positive cocci in blood cultures with Vitek 2.
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Affiliation(s)
- A Lupetti
- Dipartimento di Patologia Sperimentale, Biotecnologie Mediche, Infettivologia ed Epidemiologia, Università di Pisa, Pisa, Italy.
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