Evaluation of 500 Gram negative isolates to determine the number of major susceptibility interpretation discrepancies between the Vitek and MicroScan Walkaway for 9 antimicrobial agents

Rittenhouse, Stephen; Miller, Linda A.; Utrup, Linda J.; Poupard, James A.

doi:10.1016/s0732-8893(96)00144-7

Cited by 11 publications

(6 citation statements)

References 7 publications

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“…In total, 5 very major errors (0.26%), 6 major errors (0.32%), and 26 minor errors (1.37%) were recorded. These data are consistent with accepted error rates for clinical microbiology laboratories (2,13). No significant trend in the errors was observed for any organism or antibiotic agent tested (chi-square test, Prism 4; GraphPad Software, La Jolla, CA).…”

supporting

confidence: 86%

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

et al. 2012

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supporting

confidence: 86%

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

et al. 2012

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“…1 Another article reports minimal dis- crepancy between Vitek and MicroScan in evaluating 500 gram-negative isolates. 8 The marginal differences between these testing systems may be contributing to variability of the data reported for gram-negative organisms in health systems 2 and 3. 8 The nine organisms selected for the statistical comparison were chosen based on the prevalence of these organisms in the health systems.…”

Section: Discussionmentioning

confidence: 99%

“…8 The marginal differences between these testing systems may be contributing to variability of the data reported for gram-negative organisms in health systems 2 and 3. 8 The nine organisms selected for the statistical comparison were chosen based on the prevalence of these organisms in the health systems. This study did not include all of the organisms in the individual hospital reports.…”

Section: Discussionmentioning

confidence: 99%

Differences in Antimicrobial Susceptibility Among Hospitals in an Integrated Health System

Lubowski

Woon²,

Hogan³

et al. 2001

Infect. Control Hosp. Epidemiol.

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We evaluated the differences in antimicrobial susceptibility among hospitals in three different integrated healthcare systems. Each system provided antibiogram-susceptibility reports from representative hospitals. Reports were analyzed for statistically significant differences between hospitals in a given system for nine important organisms. We found numerous significant interhospital differences in antimicrobial-susceptibility patterns within health systems. For this reason, the practice of combining antibiotic-susceptibility data into a systemwide antibiogram should be discouraged.

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“…Previous reports indicate that automated systems for susceptibility testing are reliable in detecting quinolone-resistant enterobacteria (4,7,9,12), but there is very limited information on the accuracy of these systems with organisms expressing plasmid-mediated quinolone resistance (PMQR) mechanisms. PMQR genes determine the low level of resistance to quinolones and may favor or complement the selection of additional mechanisms (5,6,10).…”

mentioning

confidence: 99%

Evaluation of Three Automated Systems for Susceptibility Testing of Enterobacteria Containing qnrB, qnrS, and/or aac(6′)-Ib-cr

et al. 2011

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The accuracy of the MicroScan WalkAway, BD Phoenix, and Vitek-2 systems for susceptibility testing of quinolones and aminoglycosides against 68 enterobacteria containing qnrB, qnrS, and/or aac(6)-Ib-cr was evaluated using reference microdilution. Overall, one very major error (0.09%), 6 major errors (0.52%), and 45 minor errors (3.89%) were noted.Previous reports indicate that automated systems for susceptibility testing are reliable in detecting quinolone-resistant enterobacteria (4, 7, 9, 12), but there is very limited information on the accuracy of these systems with organisms expressing plasmid-mediated quinolone resistance (PMQR) mechanisms. PMQR genes determine the low level of resistance to quinolones and may favor or complement the selection of additional mechanisms (5, 6, 10). They code for Qnr proteins, the acetyltransferase Aac(6Ј)-Ib-cr, or the efflux systems QepA and OqxAB. Aac(6Ј)-Ib-cr also confers resistance to tobramycin and amikacin.Detection of strains harboring PMQR mechanisms usually depends on genotypic assays (often PCR amplification and sequencing of these genes), as we currently lack reliable phenotypic methods to detect these organisms. Qnr proteins and Aac(6Ј)-Ib-cr seem to be the most relevant PMQR mechanisms in Spain and other European countries, as the plasmid locations of the oqxAB (present in the chromosomes of most Klebsiella pneumoniae strains) and qepA genes have uncommonly been described in this geographical location. Also, most enterobacteria with plasmid-mediated qnr genes contain qnrA, qnrB, or qnrS alleles, while those with qnrD and qnrC still seem to be exceptional.A previous study had evaluated four clinical strains of K. pneumoniae and the corresponding Escherichia coli transconjugants carrying the qnrA1 gene with four automated systems (11). In this study, the performance of three automated instruments for susceptibility testing of quinolones and aminoglycosides against bacteria containing qnrB, qnrS, and/or aac(6Ј)Ib-cr was evaluated.We tested 68 clinical isolates (one per patient), collected at two centers in northern (Hospital Universitario Marqués de Valdecilla, Santander) and southern (Hospital Virgen Macarena, Seville) Spain, as indicated in Table 1.qnrB, qnrS, and acc(6Ј)-Ib-cr were detected by multiplex PCR and sequencing of the obtained amplicons, as described elsewhere (1). In total, 47 isolates produced a qnr determinant (7 qnrB-related alleles, 40 qnrS1-related alleles), and 26 produced acc(6Ј)-Ib-cr, with 5 isolates producing both types of genes.Reference MIC values for the tested organisms were determined by a broth microdilution assay according to CLSI guidelines (2). The following antimicrobial agents and concentrations (mg/liter) were tested: nalidixic acid (0.5 to 1,024), ciprofloxacin (0.015 to 32), norfloxacin (0.015 to 32), levofloxacin (0.015 to 32), gentamicin (0.06 to 128), tobramycin (0.06 to 128), and amikacin (0.06 to 128). E. coli ATCC 25922 and Pseudomonas aeruginosa ATCC 27853 were used as control strains.

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Evaluation of 500 Gram negative isolates to determine the number of major susceptibility interpretation discrepancies between the Vitek and MicroScan Walkaway for 9 antimicrobial agents

Cited by 11 publications

References 7 publications

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

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

Differences in Antimicrobial Susceptibility Among Hospitals in an Integrated Health System

Evaluation of Three Automated Systems for Susceptibility Testing of Enterobacteria Containing qnrB, qnrS, and/or aac(6′)-Ib-cr

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