scholarly journals Validation of Sensititre Dry-Form Broth Microdilution Panels for Susceptibility Testing of Ceftazidime-Avibactam, a Broad-Spectrum-β-Lactamase Inhibitor Combination

2015 ◽  
Vol 59 (8) ◽  
pp. 5036-5039 ◽  
Author(s):  
Ronald N. Jones ◽  
Nicole M. Holliday ◽  
Kevin M. Krause
Keyword(s):  
Broad Spectrum ◽  
Susceptibility Testing ◽  
Clinical Microbiology Laboratory ◽  
Microbiology Laboratory ◽  
Broth Microdilution ◽  
Content Type ◽  
Serious Infections ◽  
Validation Experiment ◽  
Inhibitor Combination ◽  
Lactamase Inhibitor

ABSTRACTCeftazidime-avibactam is a broad-spectrum-β-lactamase inhibitor combination in late-stage clinical development for the treatment of serious infections. In preparation for clinical microbiology laboratory use, a validation experiment was initiated to evaluate a commercial broth microdilution product (Sensititre dried MIC susceptibility system) compared to reference panels using 525 recent clinical isolates. Among 11 pathogen groups, all had Sensititre MIC/reference MIC ratios predominantly at 1 (47.5% to 97.5%), and automated and manual endpoint results did not differ.EnterobacteriaceaeMIC comparisons showed a modest skewing of Sensititre MIC results toward an elevated MIC (33.9%), but the essential agreement was 98.9% with 100.0% reproducibility. In conclusion, Sensititre panels produced accurate ceftazidime-avibactam MIC results, allowing quality MIC guidance for therapy following regulatory approvals.

scholarly journals Multicenter Clinical Evaluation of Etest Meropenem-Vaborbactam (bioMérieux) for Susceptibility Testing of Enterobacterales (Enterobacteriaceae) and Pseudomonas aeruginosa

2019 ◽  
Vol 58 (1) ◽  
Author(s):  
Sophonie Jean ◽  
Sheri Garrett ◽  
Claire Anglade ◽  
Laurence Bridon ◽  
Leanne Davies ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Susceptibility Testing ◽  
Reference Method ◽  
Individual Species ◽  
Beta Lactamase ◽  
Content Type ◽  
European Committee ◽  
Tract Infections ◽  
Inhibitor Combination ◽  
Lactamase Inhibitor

ABSTRACT Meropenem-vaborbactam (MEV) is a novel carbapenem–beta-lactamase inhibitor combination antibiotic approved by the U.S. Food and Drug Administration (FDA) for treatment of complicated urinary tract infections, including pyelonephritis, in adults. In this study, we evaluated the performance of Etest MEV (bioMérieux, Marcy l’Etoile, France) compared to that of broth microdilution for 629 Enterobacterales and 163 Pseudomonas aeruginosa isolates. According to CLSI/FDA breakpoints, 13 Enterobacterales isolates (12 clinical and 1 challenge) were resistant to MEV. Overall, Etest MEV demonstrated 92.4% essential agreement (EA), 99.2% category agreement (CA), 0% very major errors (VME), 0% major errors (ME), and 0.8% minor errors (mE) with clinical and challenge isolates of Enterobacterales. Individual species demonstrated EA rates of ≥80%, with the exception of Proteus mirabilis, for which clinical and challenge isolates demonstrated 34.3% EA, 97.1% CA, 0% ME, and 2.9% mE, precluding the use of Etest MEV with this species. Excluding P. mirabilis, MEV Etest MEV demonstrated 95.8% EA, 99.3% CA, 0% VME, 0% ME, and 0.7% mE with Enterobacterales isolates. When evaluated using European Committee on Antimicrobial Susceptibility Testing (EUCAST) breakpoints, Etest MEV performance with clinical (16 MEV resistant) and challenge (12 MEV resistant) isolates of Enterobacterales (excluding P. mirabilis) and P. aeruginosa demonstrated an unacceptably high VME rate of 7.1% despite 95.2% EA, 99.2% CA, and 0.5% ME compared to the reference method. In conclusion, we report that Etest MEV is accurate and reproducible for MEV susceptibility testing for P. aeruginosa and Enterobacterales, with the exception of P. mirabilis, using CLSI/FDA breakpoints. Etest MEV should not be used with P. mirabilis due to unacceptable analytical performance.

scholarly journals Detecting In-Vitro Colistin Resistance- A Comparative Study Between Broth Microdilution Versus Vitek-2 For Colistin Susceptibility Testing

2020 ◽  
Vol 7 (7) ◽  
pp. A336-340
Author(s):  
Hena Butta ◽  
Leena Mendiratta ◽  
Raman Sardana ◽  
Kirti Gilotra ◽  
Sana Hasan ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Pseudomonas Aeruginosa ◽  
Clinical Microbiology ◽  
Susceptibility Testing ◽  
Clinical Microbiology Laboratory ◽  
Microbiology Laboratory ◽  
Broth Microdilution ◽  
Major Error ◽  
Acinetobacter Baumanii ◽  
Vitek 2

Background: Susceptibility testing for polymyxins is a great challenge for a Clinical Microbiology laboratory. There are several methodological issues associated with MIC (Minimum Inhibitory Concentration) determination of colistin. Methods: In our study, we have compared the results of colistin susceptibility testing by Automated system (Vitek-2, Biomerieux, France) with the reference Broth Microdilution method (BMD) to identify the type of discrepancies by Vitek-2 method and thus develop a practical and accurate approach for colistin susceptibility testing in a Clinical Microbiology laboratory. A total of 730 strains of Gram negative bacteria [Escherichia coli (325), Klebsiella sp.(346), Acinetobacter baumanii complex (37) and Pseudomonas aeruginosa (22)] from 485 patents were tested simultaneously by BMD and Vitek-2 method for colistin susceptibility testing. Results: The Essential agreement (EA), Categorical agreement (CA), Very major error (VME) and Major error (ME) rates for Klebsiella sp. were 87.3%, 89.3%, 8% and 2.3% respectively, for Escherichia coli were 88.3%, 89.5%, 9.2% and 1.2%  respectively, for Acinetobacter baumannii complex were 89.1%, 91.8%, 8.1% and 0% respectively, for Pseudomonas aeruginosa were 68.1%, 72.7%, 0% and 27.2% respectively. Conclusions: Colistin susceptibility testing by Vitek-2 method is an easily adoptable method and the results of Vitek-2 with reference to BMD are acceptable to a great extent in Klebsiella sp., Escherichia coli and Acinetobacter baumanii complex. So, we believe that Vitek-2 method may be used for colistin susceptibility testing in low risk patients. However, BMD should be used in high risk immunosupressed and immunocompromised patients who are admitted in critical care units. For Pseudomonas aeruginosa, BMD should be routinely used.

scholarly journals Evaluation of the MicroScan Colistin Well and Gradient Diffusion Strips for Colistin Susceptibility Testing in Enterobacteriaceae

2019 ◽  
Vol 57 (5) ◽  
Author(s):  
Joseph D. Lutgring ◽  
Anny Kim ◽  
Davina Campbell ◽  
Maria Karlsson ◽  
Allison C. Brown ◽  
...  
Keyword(s):  
Error Rate ◽  
Susceptibility Testing ◽  
Clinical Microbiology Laboratory ◽  
Microbiology Laboratory ◽  
Major Error ◽  
Testing Methods ◽  
Content Type ◽  
Laboratory Capacity ◽  
Gradient Diffusion

ABSTRACT Many laboratories are unable to perform colistin susceptibility testing. Diffusion-based antimicrobial susceptibility testing methods are not recommended, and not all laboratories have the capacity to perform broth microdilution (BMD). Using a multistep tiered approach, we investigated whether the adapted use of the MicroScan colistin well (4 μg/ml) could enhance laboratory capacity for the detection and subsequent molecular characterization of colistin-resistant Enterobacteriaceae. For the MicroScan colistin well, categorical agreement with BMD was 92.7%, and the very major error rate was 10.7%. For gradient diffusion strips, the categorical agreement was 86.4%, and the very major error rate was 53.6%. The MicroScan colistin well detected all isolates carrying mcr-1 or mcr-2 genes (n = 16), but gradient diffusion strips identified an MIC of ≥4 for colistin for only 62.5% of these isolates. A 6-month prospective phenotypic and genotypic study performed at a single clinical microbiology laboratory assessed isolates growing in the MicroScan colistin well for concordance. While 37 of 39 isolates growing in the MicroScan colistin well displayed a colistin MIC of ≥4 by BMD, all were determined to be negative for the mcr-1 and mcr-2 genes by PCR. A retrospective review of all Escherichia coli, Klebsiella spp., and Enterobacter spp. tested by MicroScan at this laboratory in 2016 identified 260 of 7,894 (3.3%) isolates that grew in the MicroScan colistin well. Based on the data presented, clinical and public health laboratories could use the MicroScan colistin well as a first screen for the detection of isolates displaying elevated colistin MICs, which could then undergo further characterization.

scholarly journals Agreement Assessment of Tigecycline Susceptibilities Determined by the Disk Diffusion and Broth Microdilution Methods among Commonly Encountered Resistant Bacterial Isolates: Results from the TigecyclineIn VitroSurveillance in Taiwan (TIST) Study, 2008 to 2010

2011 ◽  
Vol 56 (3) ◽  
pp. 1414-1417 ◽  
Author(s):  
Jien-Wei Liu ◽  
Wen-Chien Ko ◽  
Cheng-Hua Huang ◽  
Chun-Hsing Liao ◽  
Chin-Te Lu ◽  
...  
Keyword(s):  
Susceptibility Testing ◽  
Total Error ◽  
Error Rates ◽  
Resistant Bacteria ◽  
Drug Resistant ◽  
Broth Microdilution ◽  
Content Type ◽  
E Coli ◽  
Drug Resistant Bacteria

ABSTRACTThe TigecyclineIn VitroSurveillance in Taiwan (TIST) study, initiated in 2006, is a nationwide surveillance program designed to longitudinally monitor thein vitroactivity of tigecycline against commonly encountered drug-resistant bacteria. This study compared thein vitroactivity of tigecycline against 3,014 isolates of clinically important drug-resistant bacteria using the standard broth microdilution and disk diffusion methods. Species studied included methicillin-resistantStaphylococcus aureus(MRSA;n= 759), vancomycin-resistantEnterococcus faecium(VRE;n= 191), extended-spectrum β-lactamase (ESBL)-producingEscherichia coli(n= 602), ESBL-producingKlebsiella pneumoniae(n= 736), andAcinetobacter baumannii(n= 726) that had been collected from patients treated between 2008 and 2010 at 20 hospitals in Taiwan. MICs and inhibition zone diameters were interpreted according to the currently recommended U.S. Food and Drug Administration (FDA) criteria and the European Committee on Antimicrobial Susceptibility Testing (EUCAST) criteria. The MIC90values of tigecycline against MRSA, VRE, ESBL-producingE. coli, ESBL-producingK. pneumoniae, andA. baumanniiwere 0.5, 0.125, 0.5, 2, and 8 μg/ml, respectively. The total error rates between the two methods using the FDA criteria were high: 38.4% for ESBL-producingK. pneumoniaeand 33.8% forA. baumannii. Using the EUCAST criteria, the total error rate was also high (54.6%) forA. baumanniiisolates. The total error rates between these two methods were <5% for MRSA, VRE, and ESBL-producingE. coli. For routine susceptibility testing of ESBL-producingK. pneumoniaeandA. baumanniiagainst tigecycline, the broth microdilution method should be used because of the poor correlation of results between these two methods.

scholarly journals Antifungal Susceptibility Testing of Malassezia spp. with an Optimized Colorimetric Broth Microdilution Method

2017 ◽  
Vol 55 (6) ◽  
pp. 1883-1893 ◽  
Author(s):  
Cheryl Leong ◽  
Antonino Buttafuoco ◽  
Martin Glatz ◽  
Philipp P. Bosshard
Keyword(s):  
Susceptibility Testing ◽  
Skin Diseases ◽  
Antifungal Susceptibility ◽  
Drug Susceptibility ◽  
Drug Susceptibility Testing ◽  
Broth Microdilution ◽  
Content Type ◽  
Microdilution Method ◽  
Broth Microdilution Method ◽  
Colorimetric Indicator

ABSTRACTMalasseziais a genus of lipid-dependent yeasts. It is associated with common skin diseases such as pityriasis versicolor and atopic dermatitis and can cause systemic infections in immunocompromised individuals. Owing to the slow growth and lipid requirements of these fastidious yeasts, convenient and reliable antifungal drug susceptibility testing assays forMalasseziaspp. are not widely available. Therefore, we optimized a broth microdilution assay for the testing ofMalasseziathat is based on the CLSI and EUCAST assays forCandidaand other yeasts. The addition of ingredients such as lipids and esculin provided a broth medium formulation that enabled the growth of allMalasseziaspp. and could be read, with the colorimetric indicator resazurin, by visual and fluorescence readings. We tested the susceptibility of 52 strains of 13Malasseziaspecies to 11 commonly used antifungals. MIC values determined by visual readings were in good agreement with MIC values determined by fluorescence readings. The lowest MICs were found for the azoles itraconazole, posaconazole, and voriconazole, with MIC90values of 0.03 to 1.0 μg/ml, 0.06 to 0.5 μg/ml, and 0.03 to 2.0 μg/ml, respectively. AllMalasseziaspp. were resistant to echinocandins and griseofulvin. SomeMalasseziaspp. also showed high MIC values for ketoconazole, which is the most widely recommended topical antifungal to treatMalasseziaskin infections. In summary, our assay enables the fast and reliable susceptibility testing ofMalasseziaspp. with a large panel of different antifungals.

scholarly journals Impact of Changes in Clinical Microbiology Laboratory Location and Ownership on the Practice of Infectious Diseases

2020 ◽  
Vol 58 (5) ◽  
Author(s):  
Michael Pentella ◽  
Melvin P. Weinstein ◽  
Susan E. Beekmann ◽  
Philip M. Polgreen ◽  
Richard T. Ellison
Keyword(s):  
Infectious Diseases ◽  
Clinical Microbiology ◽  
Clinical Microbiology Laboratory ◽  
Microbiology Laboratory ◽  
Emerging Infections ◽  
Clinical Practices ◽  
Sentinel Network ◽  
Effective Implementation ◽  
Serious Infections ◽  
The Impact

ABSTRACT The number of onsite clinical microbiology laboratories in hospitals is decreasing, likely related to the business model for laboratory consolidation and labor shortages, and this impacts a variety of clinical practices, including that of banking isolates for clinical or epidemiologic purposes. To determine the impact of these trends, infectious disease (ID) physicians were surveyed regarding their perceptions of offsite services. Clinical microbiology practices for retention of clinical isolates for future use were also determined. Surveys were sent to members of the Infectious Diseases Society of America’s (IDSA) Emerging Infections Network (EIN). The EIN is a sentinel network of ID physicians who care for adult and/or pediatric patients in North America and who are members of IDSA. The response rate was 763 (45%) of 1,680 potential respondents. Five hundred forty (81%) respondents reported interacting with the clinical microbiology laboratory. Eighty-six percent of respondents thought an onsite laboratory very important for timely diagnostic reporting and ongoing communication with the clinical microbiologist. Thirty-five percent practiced in institutions where the core microbiology laboratory has been moved offsite, and an additional 7% (n = 38) reported that movement of core laboratory functions offsite was being considered. The respondents reported that only 24% of laboratories banked all isolates, with the majority saving isolates for less than 30 days. Based on these results, the trend toward centralized core laboratories negatively impacts the practice of ID physicians, potentially delays effective implementation of prompt and targeted care for patients with serious infections, and similarly adversely impacts infection control epidemiologic investigations.

scholarly journals Effect of the β-Lactamase Inhibitor Vaborbactam Combined with Meropenem against Serine Carbapenemase-Producing Enterobacteriaceae

2016 ◽  
Vol 60 (9) ◽  
pp. 5454-5458 ◽  
Author(s):  
Mariana Castanheira ◽  
Paul R. Rhomberg ◽  
Robert K. Flamm ◽  
Ronald N. Jones
Keyword(s):  
Multidrug Resistant ◽  
Inhibitor Concentration ◽  
Efflux System ◽  
Content Type ◽  
Fixed Concentration ◽  
Serious Infections ◽  
Elevated Expression ◽  
Further Development ◽  
Susceptibility Breakpoint ◽  
Lactamase Inhibitor

ABSTRACTKlebsiella pneumoniaecarbapenemase (KPC)-producing isolates have become increasingly prevalent worldwide, and these organisms are often multidrug resistant, limiting the therapeutic options available for treating infections. We evaluated the activity of meropenem combined with the serine β-lactamase inhibitor vaborbactam (formerly RPX7009) against 315 serine carbapenemase-producingEnterobacteriaceae(CPE) isolates by use of checkerboard-designed panels to assess the optimal inhibitor concentration (range tested, 0.5 to 32 μg/ml). Overall, meropenem alone (MIC50and MIC90, 16 and >64 μg/ml, respectively) inhibited only 2.2% of the isolates at ≤1 μg/ml (the CLSI susceptibility breakpoint) and 7.3% of the isolates at ≤2 μg/ml (the EUCAST breakpoint). Vaborbactam restored meropenem activity for 72.7 to 98.1% of CPE isolates at ≤2 μg/ml, and maximum potentiation was achieved with fixed concentrations of ≥8 μg/ml of the inhibitor (≥96.5% of isolates were inhibited at ≤2 μg/ml of meropenem-vaborbactam). Meropenem-vaborbactam with a fixed concentration of 8 μg/ml of the inhibitor (MIC50, ≤0.06 μg/ml for all organisms) inhibited 93.7% of the CPE isolates displaying elevated meropenem MICs at ≤1 μg/ml. Meropenem-vaborbactam MICs were elevated for isolates producing metallo-β-lactamases (MIC, 16 to >64 μg/ml) or displaying decreased expression of OmpK37 and/or elevated expression of the AcrAB-TolC efflux system (MIC, 16 μg/ml). Vaborbactam showed no antibacterial activity alone (all MICs, >64 μg/ml). Meropenem-vaborbactam appears to be a good candidate for further development and it could increase the options for treatment of serious infections caused by carbapenemase-producing pathogens.

scholarly journals Isolation of Campylobacter Species from Stool Samples by Use of a Filtration Method: Assessment from a United States-Based Population

2017 ◽  
Vol 55 (7) ◽  
pp. 2204-2207 ◽  
Author(s):  
Irving Nachamkin ◽  
Phi Nguyen
Keyword(s):  
United States ◽  
Clinical Microbiology ◽  
Clinical Microbiology Laboratory ◽  
Microbiology Laboratory ◽  
Filtration Method ◽  
Content Type ◽  
Stool Samples ◽  
Campylobacter Species ◽  
Clinically Significant ◽  
Microaerobic Conditions

ABSTRACT Fecal samples submitted to our clinical microbiology laboratory from patients in the Philadelphia region were prospectively analyzed for Campylobacter species other than C. jejuni and C. coli using a filtration method and microaerobic conditions with increased H 2 concentrations. Of 225 samples tested, 13 (5.8%) yielded Campylobacter species, with frequent isolation of C. concisus . The majority of Campylobacter species were not clinically significant. Additional studies in U.S. populations are warranted.

scholarly journals Multicenter Evaluation of the Etest Gradient Diffusion Method for Ceftolozane-Tazobactam Susceptibility Testing of Enterobacteriaceae and Pseudomonas aeruginosa

2018 ◽  
Vol 56 (9) ◽  
Author(s):  
Adam L. Bailey ◽  
Tom Armstrong ◽  
Hari-Prakash Dwivedi ◽  
Gerald A. Denys ◽  
Janet Hindler ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Susceptibility Testing ◽  
Clinical Isolates ◽  
Diffusion Method ◽  
Beta Lactam ◽  
Content Type ◽  
Gradient Diffusion ◽  
Tract Infections ◽  
Abdominal Infections ◽  
Inhibitor Combination

ABSTRACT Ceftolozane-tazobactam (C/T) is a novel beta-lactam–beta-lactamase inhibitor combination antibiotic approved by the U.S. Food and Drug Administration in 2014 for the treatment of complicated intra-abdominal infections (in combination with metronidazole) and complicated urinary tract infections. In this study, we evaluated the performance of the C/T Etest, a gradient diffusion method. C/T Etest was compared to broth microdilution (BMD) for 51 Enterobacteriaceae challenge isolates and 39 Pseudomonas aeruginosa challenge isolates at three clinical sites. Essential agreement (EA) between the methods ranged from 47 to 49/51 (92.2 to 96.1%) for the Enterobacteriaceae, and categorical agreement (CA) ranged from 49 to 51/51 (96.1 to 100.0%). EA and CA for P. aeruginosa were 100% at all sites. The C/T Etest was also compared to BMD for susceptibility testing on 966 clinical isolates (793 Enterobacteriaceae, including 167 Klebsiella pneumoniae and 159 Escherichia coli isolates, in addition to 173 P. aeruginosa isolates) collected at four clinical sites. EA between Etest and BMD was 96.9% for Enterobacteriaceae isolates and 98.8% for P. aeruginosa isolates. Within the Enterobacteriaceae, isolates from each species examined had >96% CA. For the clinical isolates, no very major errors were identified but two major errors were found (one for K. pneumoniae and one for Providencia rettgeri). By BMD, 47.0% of Enterobacteriaceae and 46.2% of P. aeruginosa challenge strains were nonsusceptible to C/T by CLSI breakpoint criteria; 8.2% of clinical Enterobacteriaceae isolates and 12.1% of clinical P. aeruginosa isolates were nonsusceptible to C/T by CLSI breakpoint criteria. In conclusion, Etest is accurate and reproducible for C/T susceptibility testing of Enterobacteriaceae and P. aeruginosa.

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