scholarly journals Comparative performances of Vitek-2, Disk Diffusion, and Broth Microdilution for antimicrobial susceptibility testing of canine Staphylococcus pseudintermedius

2021 ◽  
Author(s):  
Elisa Rampacci ◽  
Michele Trotta ◽  
Caterina Fani ◽  
Serenella Silvestri ◽  
Valentina Stefanetti ◽  
...  
Keyword(s):  
Antimicrobial Susceptibility ◽  
Susceptibility Testing ◽  
Antimicrobial Susceptibility Testing ◽  
Disk Diffusion ◽  
Health Concern ◽  
Broth Microdilution ◽  
Major Error ◽  
Staphylococcus Pseudintermedius ◽  
Cutaneous Infections ◽  
Vitek 2

Staphylococcus pseudintermedius is the primary cause of canine cutaneous infections and sporadically isolated as pathogen from humans. Rapidly emerging antibiotic-resistant strains are creating serious health concern so that accurate and timely antimicrobial susceptibility testing (AST) is crucial for patient care. Here, the performances of AST methods Vitek-2, Disk Diffusion (DD) and Broth Microdilution (BMD) were compared for the determination of susceptibility of 79 S. pseudintermedius isolates from canine cutaneous infections and one from human pyoderma to oxacillin (OXA), amoxicillin/clavulanate (AMC), cephalothin (CEF), gentamicin (GEN), enrofloxacin (ENR), doxycycline (DOX), clindamycin (CLI), inducible clindamycin resistance (ICR), mupirocin (MUP) and trimethoprim-sulfamethoxazole (SXT). Overall, the agreement of DD and Vitek-2 using veterinary AST-GP80 card with reference BMD was ≥ 90%, suggesting reliable AST performances. While DD generated mainly minor errors and one major error for OXA, Vitek-2 produced one very major error for GEN and it failed in identifying one ICR-positive isolate. Moreover, five bacteria were diagnosed as ICR-positive by Vitek-2 but they showed a non-induction resistance phenotype by manual methods. All S. pseudintermedius were interpreted as susceptible or intermediately susceptible to DOX using CLSI breakpoints for human staphylococci that match the DOX concentration range included in AST-GP80. However, this could lead to inappropriate antimicrobial prescription for S. pseudintermedius infections in companion animals. Considering the clinical and epidemiological importance of S. pseudintermedius , we encourage updating action by the system manufacturer to address AST for this bacterium.

scholarly journals Cefiderocol Antimicrobial Susceptibility Testing against Multidrug-Resistant Gram-Negative Bacilli: a Comparison of Disk Diffusion to Broth Microdilution

2020 ◽  
Vol 59 (1) ◽  
pp. e01649-20 ◽  
Author(s):  
C. Paul Morris ◽  
Yehudit Bergman ◽  
Tsigedera Tekle ◽  
John A. Fissel ◽  
Pranita D. Tamma ◽  
...  
Keyword(s):  
Antimicrobial Susceptibility ◽  
Susceptibility Testing ◽  
Multidrug Resistant ◽  
Antimicrobial Susceptibility Testing ◽  
Disk Diffusion ◽  
Broth Microdilution ◽  
Gram Negative ◽  
Content Type ◽  
Carbapenem Resistant ◽  
Alternative Approach

ABSTRACTAntimicrobial susceptibility testing (AST) of cefiderocol poses challenges because of its unique mechanism of action (i.e., requiring an iron-depleted state) and due to differences in interpretative criteria established by the Clinical and Laboratory Standards Institute (CLSI), U.S. Food and Drug Administration (FDA), and European Committee on Antimicrobial Susceptibility Testing (EUCAST). Our objective was to compare cefiderocol disk diffusion methods (DD) to broth microdilution (BMD) for AST of Gram-negative bacilli (GNB). Cefiderocol AST was performed on consecutive carbapenem-resistant Enterobacterales (CRE; 58 isolates) and non-glucose-fermenting GNB (50 isolates) by BMD (lyophilized panels; Sensititre; Thermo Fisher) and DD (30 μg; research-use-only [RUO] MASTDISCS and FDA-cleared HardyDisks). Results were interpreted using FDA (prior to 28 September 2020 update), EUCAST, and investigational CLSI breakpoints (BPs). Categorical agreement (CA), minor errors (mE), major errors (ME), and very major errors (VME) were calculated for DD methods. The susceptibilities of all isolates by BMD were 72% (FDA), 75% (EUCAST) and 90% (CLSI). For DD methods, EUCAST BPs demonstrated lower susceptibility at 65% and 66%, compared to 74% and 72% (FDA) and 87% and 89% (CLSI) by HardyDisks and MASTDISCS, respectively. CA ranged from 75% to 90%, with 8 to 25% mE, 0 to 19% ME, and 0 to 20% VME and varied based on disk, GNB, and BPs evaluated. Both DD methods performed poorly for Acinetobacter baumannii complex. There is considerable variability when cefiderocol ASTs are interpreted using CLSI, FDA, and EUCAST breakpoints. DD offers a convenient alternative approach to BMD methods for cefiderocol AST, with the exception of A. baumannii complex isolates.

scholarly journals Performance of Vitek 2 for Antimicrobial Susceptibility Testing of Acinetobacter baumannii, Pseudomonas aeruginosa, and Stenotrophomonas maltophilia with Vitek 2 (2009 FDA) and CLSI M100S 26th Edition Breakpoints

2016 ◽  
Vol 55 (2) ◽  
pp. 450-456 ◽  
Author(s):  
April M. Bobenchik ◽  
Eszter Deak ◽  
Janet A. Hindler ◽  
Carmen L. Charlton ◽  
Romney M. Humphries
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Acinetobacter Baumannii ◽  
Antimicrobial Susceptibility ◽  
Stenotrophomonas Maltophilia ◽  
Susceptibility Testing ◽  
Antimicrobial Susceptibility Testing ◽  
Broth Microdilution ◽  
Content Type ◽  
Vitek 2 ◽  
Improved Performance

ABSTRACTThe performances of Vitek 2 AST-GN69 and AST-XN06 cards were compared to Clinical and Laboratory Standards Institute (CLSI) reference broth microdilution (BMD) for 99 isolates ofPseudomonas aeruginosa, 26Acinetobacter baumanniiisolates, and 11Stenotrophomonas maltophiliaisolates. In total, 15 antimicrobials were evaluated, with 11 forP. aeruginosa, 14 forA. baumannii, and 2 forS. maltophilia. Categorical agreement (CA) was assessed using both Vitek 2 breakpoints and 2016 CLSI M100S 26th edition breakpoints. The essential agreement values forP. aeruginosa,A. baumannii, andS. maltophiliawere 99.5%, 99.2%, and 100%, respectively. The CA values forP. aeruginosa,A. baumannii, andS. maltophiliawere 94.1%, 92.7%, and 95.5%, respectively, by the Vitek 2 breakpoints, and 93.4%, 92.3%, and 95.5%, respectively, by the CLSI breakpoints. Overall, the Vitek 2 performance was comparable to that of BMD using both Vitek 2 breakpoints and 2016 CLSI M100S 26th edition breakpoints. Improved performance was noted for the reformulated piperacillin-tazobactam and imipenem found on the AST-GN69 card, with no very major or major errors noted when using the CLSI breakpoints.

scholarly journals Performance Evaluation of BD Phoenix NMIC-413 Antimicrobial Susceptibility Testing Panel for Imipenem, Meropenem, and Ertapenem Against Clinical Carbapenem-Resistant and Carbapenem-Susceptible Enterobacterales

2021 ◽  
Vol 8 ◽  
Author(s):  
Jingjia Zhang ◽  
Peiyao Jia ◽  
Ying Zhu ◽  
Ge Zhang ◽  
Yingchun Xu ◽  
...  
Keyword(s):  
Antimicrobial Susceptibility ◽  
Susceptibility Testing ◽  
Antimicrobial Susceptibility Testing ◽  
Disk Diffusion ◽  
Diffusion Method ◽  
Screening Methods ◽  
Major Error ◽  
Disk Diffusion Method ◽  
Suitable Alternative ◽  
Carbapenem Resistant

Purpose: The infection of carbapenem-resistant Enterobacterales (CRE) has become a major clinical and healthcare problem worldwide. The screening methods of CRE have been extensively developed but still need improving [e.g., tests with accurate and simple minimum inhibitory (MICs)]. In this study, the performance of the BD Phoenix NMIC-413 AST panel was evaluated against clinical CRE and carbapenem-susceptible Enterobacterales (CSE) in China. The panel was first evaluated in the Chinese clinical lab.Methods: Antimicrobial susceptibility testing of 303 clinical Enterobacterales isolates were conducted by broth microdilution (BMD), Phoenix NMIC-413 AST panel, and disk diffusion method for imipenem, ertapenem, and meropenem. Considering BMD is a gold standard, essential agreement (EA), categorical agreement (CA), minor error (MIE), major error (ME), and very major error (VME) were determined according to CLSI guidelines. CA and EA > 90%, ME <3%, and VME <1.5% were considered as acceptable criteria. Polymerase chain reaction and sanger sequencing were performed to determine the β-lactamase genotypes of CRE isolates.Results: Three hundred and three isolates included 195 CREs and 108 CSEs were enrolled according to the BMD-MIC values of three carbapenems. Tested CREs showing 100 blaKPC−2-positive organisms, 31 blaIMP-positive organisms, 28 blaNDM-positive organisms, 5 blaVIM-positive organisms, 2 both blaIMP and blaVIM-positive organisms, 2 blaOXA−48-positive organisms, and 27 isolates without carbapenemase genes. For the Phoenix NMIC-413 method, CA and EA rates >93%, MIE rates <5%, ME rates <1.75%, and VME rates were 0%, across the three drugs. For the disk diffusion method, the CA rates for three drugs were all >93%, while the MIE and ME rates were all <5 and <3%, respectively. VME rate was 3.28% for imipenem, exceeded the cut-off value specified by CLSI M52, 0 and 0.56% for ertapenem and meropenem, separately.Conclusion: Based on the genomic data, the detection of CRE and CSE was more reliable using the BD Phoenix NMIC-413 panel compared to the BMD and disk approaches. Therefore, our study supports the use of BD Phoenix NMIC-413 panel as a suitable alternative to BMD for the detection of carbapenem resistant isolates in a clinical setting.

scholarly journals Comparison of Automated System Vitek-2 with Conventional Methods, for Identification and Antibiotic Sensitivity in Gram Positive Organisms.

JMS SKIMS ◽  
2019 ◽  
Vol 22 (2) ◽  
Author(s):  
Nayeem U din Wani ◽  
Nargis Bali ◽  
Lenah Bashir ◽  
Junaid Ahmad ◽  
Suhail Ahmad
Keyword(s):  
Antimicrobial Susceptibility ◽  
Susceptibility Testing ◽  
Antibiotic Sensitivity ◽  
Blood Stream ◽  
Antimicrobial Susceptibility Testing ◽  
Automated System ◽  
Major Error ◽  
Gram Positive ◽  
Manual Methods ◽  
Vitek 2

Abstract Background: Prompt identification (ID) and antimicrobial susceptibility testing (AST) of organisms causing blood stream infections has a significant impact on the morbidity and mortality associated with these infections. The need to circumvent the slow turnaround time of conventional gold standard methods has paved way for the rapid automated systems. Aim: To Compare the results of Vitek-2 for the ID and AST of Gram positive isolates with conventional manual methods. Methodology: A total of 215 non-duplicate isolates of Gram positive bacteria recovered from blood samples were part of this prospective study carried out in the Department of Microbiology. Organisms were processed on the Vitek-2 system and by manual methods (ID/AST) for comparison. Descriptive statistics was used for the presentation and comparison of data and appropriate statistical charts were used to present the data. Observations: Concordant identification (ID) results of Vitek-2 were seen with all the isolates of S. aureus, S. epidermidis, S. pneumonia, E. faecalis and E. faecium. Discordant results of Vitek-2 were seen for S. hominis (5 isolates of the organism misidentified as S. epidermidis).  No minor, major or very major error with 100% categorical agreement (CA) was seen for penicillin, cefoxitin, oxacillin, linezolid, ciprofloxacin, tetracycline, co-trimoxazole, clindamycin and erythromycin for various organisms tested. Enterococci gave minor error of 4.5% with an overall CA of 95.5% for ampicillin and a major error of 2.8% with an overall CA of 97.2% for vancomycin. Conclusion: The organisms having slow metabolic rates and late lactose fermenters (S. hominis) are prone to errors by the Vitek-2 system; hence need to be reconfirmed with other possible method. Also AST results for critical antibiotics like vancomycin need to be verified manually before reporting.  Key words: Antimicrobial Susceptibility testing, Enterococci, Vitek-2

scholarly journals A survey of methods used for antimicrobial susceptibility testing in veterinary diagnostic laboratories in the United States

2017 ◽  
Vol 29 (5) ◽  
pp. 669-675 ◽  
Author(s):  
David A. Dargatz ◽  
Matthew M. Erdman ◽  
Beth Harris
Keyword(s):  
United States ◽  
Antimicrobial Resistance ◽  
Antimicrobial Susceptibility ◽  
Susceptibility Testing ◽  
Clinical Laboratory ◽  
The United States ◽  
Antimicrobial Susceptibility Testing ◽  
Disk Diffusion ◽  
Diffusion Method ◽  
Broth Microdilution

Antimicrobial resistance is a serious threat to animal and human health worldwide, requiring a collaborative, holistic approach. The U.S. Government has developed a national strategy to address antimicrobial resistance, with one component being to monitor antimicrobial resistance in agricultural settings. We developed a survey to collect information about antimicrobial susceptibility testing (AST) from the veterinary diagnostic laboratory community in the United States, assessing current practices and technologies and determining how AST information is shared. Of the 132 surveys administered, 52 (39%) were returned. Overall, responding laboratories conducted susceptibility tests on 98,788 bacterial isolates in 2014, with Escherichia coli being the most common pathogen tested across all animal species. The 2 most common AST methods employed were the disk diffusion method (71%) and the Sensititre platform broth microdilution system (59%). Laboratories primarily used the Clinical Laboratory Standards Institute (CLSI) VET-01 standard (69%) and the automatically calculated interpretations provided by the commercial AST systems (61%) for interpreting their AST data. Only 22% of laboratories published AST data on a periodic basis, usually via annual reports published on the laboratory’s website or through peer-reviewed journals for specific pathogens. Our results confirm that disk diffusion and broth microdilution remain the standard AST methods employed by U.S. veterinary diagnostic laboratories, and that CLSI standards are commonly used for interpreting AST results. This information will help determine the most efficient standardized methodology for future surveillance. Furthermore, the current infrastructure within laboratories, once harmonized, will help provide a mechanism for conducting national surveillance programs.

scholarly journals Comparison of Agar Dilution, Disk Diffusion, MicroScan, and Vitek Antimicrobial Susceptibility Testing Methods to Broth Microdilution for Detection of Fluoroquinolone-Resistant Isolates of the FamilyEnterobacteriaceae

1999 ◽  
Vol 37 (3) ◽  
pp. 544-547 ◽  
Author(s):  
Christine D. Steward ◽  
Sheila A. Stocker ◽  
Jana M. Swenson ◽  
Caroline M. O’Hara ◽  
Jonathan R. Edwards ◽  
...  
Keyword(s):  
Antimicrobial Susceptibility ◽  
Susceptibility Testing ◽  
Error Rates ◽  
Disk Diffusion ◽  
Fluoroquinolone Resistance ◽  
Broth Microdilution ◽  
Major Error ◽  
Testing Methods ◽  
Minor Error ◽  
Agar Dilution

Fluoroquinolone resistance appears to be increasing in many species of bacteria, particularly in those causing nosocomial infections. However, the accuracy of some antimicrobial susceptibility testing methods for detecting fluoroquinolone resistance remains uncertain. Therefore, we compared the accuracy of the results of agar dilution, disk diffusion, MicroScan Walk Away Neg Combo 15 conventional panels, and Vitek GNS-F7 cards to the accuracy of the results of the broth microdilution reference method for detection of ciprofloxacin and ofloxacin resistance in 195 clinical isolates of the familyEnterobacteriaceae collected from six U.S. hospitals for a national surveillance project (Project ICARE [Intensive Care Antimicrobial Resistance Epidemiology]). For ciprofloxacin, very major error rates were 0% (disk diffusion and MicroScan), 0.9% (agar dilution), and 2.7% (Vitek), while major error rates ranged from 0% (agar dilution) to 3.7% (MicroScan and Vitek). Minor error rates ranged from 12.3% (agar dilution) to 20.5% (MicroScan). For ofloxacin, no very major errors were observed, and major errors were noted only with MicroScan (3.7% major error rate). Minor error rates ranged from 8.2% (agar dilution) to 18.5% (Vitek). Minor errors for all methods were substantially reduced when results with MICs within ±1 dilution of the broth microdilution reference MIC were excluded from analysis. However, the high number of minor errors by all test systems remains a concern.

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