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Yin D, Song P, Jiang L, Xu J, Hu F. Performance of disk diffusion method for aztreonam in combination with avibactam against Enterobacteriales. J Antimicrob Chemother 2024; 79:1309-1312. [PMID: 38564262 DOI: 10.1093/jac/dkae097] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2023] [Accepted: 03/11/2024] [Indexed: 04/04/2024] Open
Abstract
OBJECTIVES To evaluate the performance of an in-house developed disk diffusion method for aztreonam in combination with avibactam against Enterobacteriales. METHODS The in vitro antibacterial activity of aztreonam with avibactam against 204 carbapenemase-producing Enterobacteriales was determined by a disk diffusion method, with a broth microdilution method as a reference. RESULTS The optimal S/R breakpoints for disk diffusion tests of 30/20 and 10/4 µg disks, calculated by the dBETs software using the model-based approaches, were ≥22/≤21 and ≥12/≤11 mm, respectively. On the basis of the estimated breakpoints, the CAs for disk diffusion tests of 30/20 and 10/4 µg aztreonam/avibactam disks were both 98.0%, with 0.5% major error and 37.5% very major error. CONCLUSIONS The home-made disk diffusion method is an economical and practical method for clinical microbiology laboratories to determine the antibacterial susceptibility of aztreonam with avibactam against Enterobacteriales.
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Affiliation(s)
- Dandan Yin
- Institute of Antibiotics, Huashan Hospital, Fudan University, Shanghai, China
| | - Peipei Song
- Institute of Antibiotics, Huashan Hospital, Fudan University, Shanghai, China
- Department of Laboratory, Chengdu Women's and Children's Central Hospital, School of Medicine, University of Electronic Science and Technology of China, Chengdu, China
| | - Lan Jiang
- Institute of Antibiotics, Huashan Hospital, Fudan University, Shanghai, China
- Department of Laboratory, Urumqi Maternal and Child Health Care Hospital, Urumqi, China
| | - Jian Xu
- Department of Laboratory, Chengdu Women's and Children's Central Hospital, School of Medicine, University of Electronic Science and Technology of China, Chengdu, China
| | - Fupin Hu
- Institute of Antibiotics, Huashan Hospital, Fudan University, Shanghai, China
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Evaluation of the Performance of Manual Antimicrobial Susceptibility Testing Methods and Disk Breakpoints for Stenotrophomonas maltophilia. Antimicrob Agents Chemother 2023; 95:AAC.02631-20. [PMID: 33558287 PMCID: PMC8092892 DOI: 10.1128/aac.02631-20] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Stenotrophomonas maltophilia are an emerging cause of serious infections with high associated mortality in immunocompromised patients. Treatment of S. maltophilia infections is complicated by intrinsic resistance to many antimicrobials, including carbapenems, aminoglycosides, and some cephalosporins. Despite this, >90% of isolates are susceptible to trimethoprim-sulfamethoxazole (SXT), which is front-line therapy for this organism. Side-effects of SXT include bone marrow suppression, which precludes its use for many neutropenic patients. In this population, levofloxacin (LEV), minocycline (MIN), ceftazidime (CAZ), ciprofloxacin (CIP) and tigecycline (TIG) are used as alternative therapies - all of which require testing to inform susceptibilities. The reference standard method for testing S. maltophilia is broth microdilution (BMD), but very few clinical laboratories perform reference BMD. Furthermore, interpretive criteria are not available for CIP or TIG for S. maltophilia, although generic pharmacokinetic/pharmacodynamic (PK/PD) MIC breakpoints are available for these drugs. We assessed performance of disk and gradient diffusion tests relative to BMD for 109 contemporary isolates of S. maltophilia Categorical agreement for SXT, LEV and MIN disk diffusion was 93%, 89%, and 95%, respectively. Categorical agreement for SXT, LEV, MIN and CAZ gradient strips was 98%, 85%, 93%, 71%, respectively by Etest (bioMerieux), and 98%, 83%, 99%, and 73%, by MTS (Liofilchem). CIP and TGC, two clinically valuable alternatives to SXT, did not demonstrate promising disk to MIC correlates using CLSI M100 P. aeruginosa or PK/PD breakpoints. Manual commercial tests perform well for S. maltophilia, with the exception of tests for LEV and CAZ, where high error rates were observed.
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Chen J, Jiang F, Huang CW, Lin L. Rapid genotypic antibiotic susceptibility test using CRISPR-Cas12a for urinary tract infection. Analyst 2020; 145:5226-5231. [PMID: 32597917 DOI: 10.1039/d0an00947d] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
The current clinical protocol to conduct a bacterial antibiotic susceptibility test (AST) requires at least 18 hours, and cannot be accomplished during a single visit for patients. Here, a new method based on the technique of CRISPR-Cas12a is utilized to accomplish a bacterial genotypic AST within one hour with good accuracy. Two amplification approaches are employed and compared: (1) enriching the bacterial concentration by culturing in growth media; and (2) amplifying target DNA from raw samples by recombinase polymerase amplification (RPA). The results show that CRISPR combined with RPA can rapidly and accurately provide a bacterial genotypic AST of urine samples with urinary tract infections for precise antibiotic treatment. As such, this technology could open a new class of rapid bacterial genotypic AST for various infectious diseases.
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Affiliation(s)
- Juhong Chen
- Department of Mechanical Engineering, University of California, Berkeley, Berkeley, CA 94760, USA.
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Wenzler E, Lee M, Wu TJ, Meyer KA, Shields RK, Nguyen MH, Clancy CJ, Humphries RM, Harrington AT. Performance of ceftazidime/avibactam susceptibility testing methods against clinically relevant Gram-negative organisms. J Antimicrob Chemother 2020; 74:633-638. [PMID: 30534964 DOI: 10.1093/jac/dky483] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2018] [Revised: 10/18/2018] [Accepted: 10/23/2018] [Indexed: 11/13/2022] Open
Abstract
OBJECTIVES To ensure the accuracy of susceptibility testing methods for ceftazidime/avibactam. METHODS The performances of the Etest (bioMérieux), 30/20 μg disc (Hardy diagnostics) and 10/4 μg disc (Mast Group) were evaluated against the reference broth microdilution (BMD) method for 102 clinically relevant Gram-negative organisms: 69 ceftazidime- and meropenem-resistant Klebsiella pneumoniae and 33 MDR non-K. pneumoniae. Essential and categorical agreement along with major and very major error rates were determined according to CLSI guidelines. RESULTS A total of 78% of isolates were susceptible to ceftazidime/avibactam. None of the three methods met the defined equivalency threshold against all 102 organisms. The Etest performed the best, with categorical agreement of 95% and major errors of 6.3%. Against the 69 ceftazidime- and meropenem-resistant K. pneumoniae, only the Etest and the 10/4 μg disc met the equivalency threshold. None of the three methods met equivalency for the 33 MDR isolates. There were no very major errors observed in any analysis. These results were pooled with those from a previous study of 74 carbapenem-resistant Enterobacteriaceae and data from the ceftazidime/avibactam new drug application to define optimal 30/20 μg disc thresholds using the error-rate bound model-based approaches of the diffusion breakpoint estimation testing software. This analysis identified a susceptibility threshold of ≤19 mm as optimal. CONCLUSIONS Our data indicate that the Etest is a suitable alternative to BMD for testing ceftazidime/avibactam against ceftazidime- and meropenem-resistant K. pneumoniae. The 30/20 μg discs overestimate resistance and may lead to the use of treatment regimens that are more toxic and less effective.
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Affiliation(s)
- E Wenzler
- College of Pharmacy, University of Illinois at Chicago, Chicago, IL, USA
| | - M Lee
- College of Pharmacy, University of Illinois at Chicago, Chicago, IL, USA
| | - T J Wu
- College of Pharmacy, University of Illinois at Chicago, Chicago, IL, USA
| | - K A Meyer
- College of Pharmacy, University of Illinois at Chicago, Chicago, IL, USA
| | - R K Shields
- Department of Medicine, University of Pittsburgh, Pittsburgh, PA, USA.,XDR Pathogen Laboratory, University of Pittsburgh, Pittsburgh, PA, USA
| | - M H Nguyen
- Department of Medicine, University of Pittsburgh, Pittsburgh, PA, USA.,XDR Pathogen Laboratory, University of Pittsburgh, Pittsburgh, PA, USA
| | - C J Clancy
- Department of Medicine, University of Pittsburgh, Pittsburgh, PA, USA.,XDR Pathogen Laboratory, University of Pittsburgh, Pittsburgh, PA, USA.,VA Pittsburgh Healthcare System, Pittsburgh, PA, USA
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Correlation between Broth Microdilution and Disk Diffusion Results when Testing Ceftazidime-Avibactam against a Challenge Collection of Enterobacterales Isolates: Results from a Multilaboratory Study. J Clin Microbiol 2020; 58:JCM.01757-19. [PMID: 31996445 DOI: 10.1128/jcm.01757-19] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2019] [Accepted: 01/24/2020] [Indexed: 01/12/2023] Open
Abstract
We assessed the ceftazidime-avibactam disk diffusion breakpoints that provide the lowest discrepancy error rates by testing an Enterobacterales isolate collection with ceftazidime-avibactam MIC values near the breakpoints. Isolates (n = 112) were susceptibility tested by broth microdilution and disk diffusion methods in 3 laboratories. Current disk diffusion breakpoints (≥21/≤20 mm for susceptible/resistant) provided the lowest error rates, but confirmatory MIC testing is indicated for isolates with inhibition zones of 20 to 22 mm.
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Sader HS, Rhomberg PR, Doyle TB, Flamm RK, Mendes RE. Evaluation of the Revised Ceftaroline Disk Diffusion Breakpoints When Testing a Challenge Collection of Methicillin-Resistant Staphylococcus aureus Isolates. J Clin Microbiol 2018; 56:e00777-18. [PMID: 30257898 PMCID: PMC6258841 DOI: 10.1128/jcm.00777-18] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2018] [Accepted: 09/18/2018] [Indexed: 11/24/2022] Open
Abstract
We assessed ceftaroline disk diffusion breakpoints for Staphylococcus aureus when applying revised Clinical and Laboratory Standards Institute (CLSI) ceftaroline MIC breakpoints. Disk-MIC correlation was evaluated by testing a challenge collection (n = 158) of methicillin-resistant S. aureus (MRSA) isolates composed of 106 randomly selected isolates plus 52 isolates with decreased susceptibility to ceftaroline (MIC, 1 to 16 μg/ml). Disk diffusion was performed with 30-μg disks and Mueller-Hinton agar from 2 manufacturers each. Revised CLSI susceptible (S)/susceptible dose-dependent (SDD)/resistant (R) MIC breakpoints of ≤1/2 to 4/≥8 μg/ml were applied. The disk breakpoints that provided the lowest error rates were CLSI S/R breakpoints of ≥25 mm/≤19 mm, with no very major (VM) or major (Ma) errors and with minor (Mi) error rates of 0.0% for ≥2 doubling dilutions above the I or SDD (≥I + 2), 22.1% for I or SDD plus or minus 1 doubling dilution (I ± 1), and 2.3% for ≤2 doubling dilutions below the I or SDD ≤I - 2 (overall Mi error rate, 16.5%). No mutation in the penicillin-binding protein 2a (PBP2a) was observed in 5 of 15 isolates with a ceftaroline MIC of 2 μg/ml; 3 of 11 isolates with a ceftaroline MIC of 1 μg/ml exhibited mutations in the penicillin-binding domain (PBD; 1 isolate) or in the non-PBD (2 isolates). All isolates except 1, with a ceftaroline MIC of ≥4 μg/ml, showed ≥1 mutation in the PBD and/or non-PBD. In summary, results from the disk diffusion method showed a good correlation with those from the reference broth microdilution method. Our results also showed that the ceftaroline MIC distribution of isolates with no mutations in the PBP2a goes up to 4 μg/ml, and reference broth microdilution and disk diffusion methods do not properly separate wild-type from non-wild-type isolates.
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Assessment of 30/20-Microgram Disk Content versus MIC Results for Ceftazidime-Avibactam Tested against Enterobacteriaceae and Pseudomonas aeruginosa. J Clin Microbiol 2018; 56:JCM.01960-17. [PMID: 29563198 DOI: 10.1128/jcm.01960-17] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2017] [Accepted: 03/11/2018] [Indexed: 11/20/2022] Open
Abstract
We evaluated the correlation between MIC and disk diffusion inhibition zones when testing ceftazidime-avibactam, using the 30/20-μg disk and the disk diffusion and MIC breakpoints established by the U.S. FDA and the Clinical and Laboratory Standards Institute (CLSI). Organisms used included 2 groups of Enterobacteriaceae isolates and 2 groups of Pseudomonas aeruginosa isolates; 1 group of each consisted of randomly selected isolates and the second group consisted of a challenge group from thousands of surveillance isolates with an increased proportion of organisms displaying ceftazidime-avibactam MIC values close to the breakpoints. Broth microdilution, disk diffusion tests, and data analysis were performed according to reference standardized methods. Ceftazidime-avibactam breakpoints of ≤8/4 (susceptible) and ≥16/4 μg/ml (resistant) for MIC and ≥21/≤20 mm for disk diffusion, as established by the U.S. FDA and the CLSI, were applied for Enterobacteriaceae and P. aeruginosa Ceftazidime-avibactam MIC and disk zone (30/20-μg disk) correlation were acceptable when testing Enterobacteriaceae (overall, very major [VM] and major [Ma] error rates of 0.4% and 0.0%, respectively) and nearly so when testing P. aeruginosa (2.3% VM and 2.9% Ma errors). In summary, disk diffusion and broth microdilution testing results demonstrated good categorical agreement for ceftazidime-avibactam against Enterobacteriaceae and P. aeruginosa, using 30/20-μg disks.
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Humphries RM, Ambler J, Mitchell SL, Castanheira M, Dingle T, Hindler JA, Koeth L, Sei K. CLSI Methods Development and Standardization Working Group Best Practices for Evaluation of Antimicrobial Susceptibility Tests. J Clin Microbiol 2018; 56:e01934-17. [PMID: 29367292 PMCID: PMC5869819 DOI: 10.1128/jcm.01934-17] [Citation(s) in RCA: 319] [Impact Index Per Article: 53.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Effective evaluations of antimicrobial susceptibility tests (ASTs) require robust study design. The Clinical and Laboratory Standards Institute (CLSI) Subcommittee on Antimicrobial Susceptibility Testing has recognized that many published studies reporting the performance of commercial ASTs (cASTs) suffer from major design and/or analysis flaws, rendering the results difficult or impossible to interpret. This minireview outlines the current consensus of the Methods Development and Standardization Working Group of the CLSI Subcommittee on Antimicrobial Susceptibility Testing regarding best practices for systematic evaluation of the performance of an AST, including the analysis and presentation of essential data intended for publication.
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Affiliation(s)
| | - Jane Ambler
- Wockhardt, Morton Grove Pharmaceuticals, Morton Grove, Illinois, USA
| | - Stephanie L Mitchell
- Clinical Microbiology Laboratory, Children's Hospital of Pittsburgh of UPMC and University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
| | | | - Tanis Dingle
- Provincial Laboratory for Public Health, Edmonton, Alberta, Canada
- Department of Laboratory Medicine and Pathology, University of Alberta, Edmonton, Alberta, Canada
| | - Janet A Hindler
- Department of Pathology & Laboratory Medicine, University of California, Los Angeles, Los Angeles, California, USA
| | - Laura Koeth
- Laboratory Specialists, Inc., Westlake, Ohio, USA
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DePalma G, Craig BA. Bayesian monotonic errors-in-variables models with applications to pathogen susceptibility testing. Stat Med 2018; 37:487-502. [PMID: 29156492 DOI: 10.1002/sim.7533] [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: 11/16/2016] [Revised: 09/15/2017] [Accepted: 09/26/2017] [Indexed: 11/10/2022]
Abstract
Drug dilution (MIC) and disk diffusion (DIA) are the 2 most common antimicrobial susceptibility assays used by hospitals and clinics to determine an unknown pathogen's susceptibility to various antibiotics. Since only one assay is commonly used, it is important that the 2 assays give similar results. Calibration of the DIA assay to the MIC assay is typically done using the error-rate bounded method, which selects DIA breakpoints that minimize the observed discrepancies between the 2 assays. In 2000, Craig proposed a model-based approach that specifically models the measurement error and rounding processes of each assay, the underlying pathogen distribution, and the true monotonic relationship between the 2 assays. The 2 assays are then calibrated by focusing on matching the probabilities of correct classification (susceptible, indeterminant, and resistant). This approach results in greater precision and accuracy for estimating DIA breakpoints. In this paper, we expand the flexibility of the model-based method by introducing a Bayesian 4-parameter logistic model (extending Craig's original 3-parameter model) as well as a Bayesian nonparametric spline model to describe the relationship between the 2 assays. We propose 2 ways to handle spline knot selection, considering many equally spaced knots but restricting overfitting via a random walk prior and treating the number and location of knots as additional unknown parameters. We demonstrate the 2 approaches via a series of simulation studies and apply the methods to 2 real data sets.
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Affiliation(s)
- Glen DePalma
- Department of Statistics, Purdue University, 250 N. University Street, West Lafayette, 47907, IN, U.S.A
| | - Bruce A Craig
- Department of Statistics, Purdue University, 250 N. University Street, West Lafayette, 47907, IN, U.S.A
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Relative performance of antimicrobial susceptibility assays on clinical Escherichia coli isolates from animals. Vet Microbiol 2018; 214:56-64. [DOI: 10.1016/j.vetmic.2017.12.008] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2017] [Accepted: 12/11/2017] [Indexed: 01/10/2023]
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Canali C, Spillum E, Valvik M, Agersnap N, Olesen T. Real-Time Digital Bright Field Technology for Rapid Antibiotic Susceptibility Testing. Methods Mol Biol 2018; 1736:75-84. [PMID: 29322460 DOI: 10.1007/978-1-4939-7638-6_7] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Optical scanning through bacterial samples and image-based analysis may provide a robust method for bacterial identification, fast estimation of growth rates and their modulation due to the presence of antimicrobial agents. Here, we describe an automated digital, time-lapse, bright field imaging system (oCelloScope, BioSense Solutions ApS, Farum, Denmark) for rapid and higher throughput antibiotic susceptibility testing (AST) of up to 96 bacteria-antibiotic combinations at a time. The imaging system consists of a digital camera, an illumination unit and a lens where the optical axis is tilted 6.25° relative to the horizontal plane of the stage. Such tilting grants more freedom of operation at both high and low concentrations of microorganisms. When considering a bacterial suspension in a microwell, the oCelloScope acquires a sequence of 6.25°-tilted images to form an image Z-stack. The stack contains the best-focus image, as well as the adjacent out-of-focus images (which contain progressively more out-of-focus bacteria, the further the distance from the best-focus position). The acquisition process is repeated over time, so that the time-lapse sequence of best-focus images is used to generate a video. The setting of the experiment, image analysis and generation of time-lapse videos can be performed through a dedicated software (UniExplorer, BioSense Solutions ApS). The acquired images can be processed for online and offline quantification of several morphological parameters, microbial growth, and inhibition over time.
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Affiliation(s)
| | - Erik Spillum
- Philips BioCell A/S, Allerød, Denmark
- BioSense Solutions ApS, Farum, Denmark
| | | | | | - Tom Olesen
- Philips BioCell A/S, Allerød, Denmark
- BioSense Solutions ApS, Farum, Denmark
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