Evaluation of the Vitek 2 System for Susceptibility Testing of Streptococcus pneumoniae Isolates

Goessens, W. H. F.; Toom, Nicole Lemmens-den; Hageman, Joseph R; Hermans, Peter W. M.; Sluijter, Marcel; Groot, Ronald de; Verbrugh, Henri A.

doi:10.1007/s100960000332

Cited by 12 publications

(7 citation statements)

References 13 publications

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“…Comparing these results with those obtained by Jorgensen et al [20] and Goessens et al [21], we observed that we obtained almost the same percentage of agreement for benzylpenicillin (88.6 vs. 89.8 and 90.9%) and a lower percentage for cefotaxime (90.1 vs. 96.6 and 95.4%). Our percentages of minor errors for benzylpenicillin and cefotaxime were higher than those of Jorgensen et al [20] (16.7 vs. 9.3% and 17.7 vs. 11.8%), but lower than those of Goessen et al [21] (16.7 vs. 19.3% and 17.7 vs. 25.4%). As in our results, Jorgensen et al [20] described a very major error for cefotaxime and no major nor very major error for benzylpenicillin.…”

Section: Discussionsupporting

confidence: 74%

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Evaluation of the New VITEK 2 System for Determination of the Susceptibility of Clinical Isolates of <i>Streptococcus pneumoniae</i>

Diego

López²,

Coronilla³

et al. 2002

Chemotherapy

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Background: The VITEK^® 2 is a new version of the automated system for organism identification and susceptibility testing. One of the differences between this system and its predecessor, VITEK, is the ability to perform rapid susceptibility testing of Streptococcus pneumoniae. This study compares the results of susceptibility testing of S. pneumoniae using the VITEK 2 system and a commercial microbroth dilution method, Sensititre. Methods: A group of 214 clinical isolates of S. pneumoniae were selected to include isolates with previously documented penicillin resistance. The antimicrobial agents tested were benzylpenicillin, cefotaxime, erythromycin, trimethoprim/sulfamethoxazole, tetracycline, chloramphenicol, imipenem and vancomycin. Results: The best agreement was achieved with vancomycin (100%), erythromycin (95.8%) and tetracycline (95.8%). The lowest level of agreement was found with benzylpenicillin (88.6%) and cefotaxime (90.1%). We observed rates of 12.3 and 15.7% for minor errors with penicillin and cefotaxime, respectively, and 1 very major error for cefotaxime. Conclusion: The VITEK 2 allows rapid determination of the antimicrobial susceptibility of S. pneumoniae and demonstrated a good degree of agreement with the Sensititre method for most of the antimicrobials tested.

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Section: Discussionsupporting

confidence: 74%

“…In the present study, only 11 (5.4%) of the 214 isolates did not grow in the VITEK 2 susceptibility cards, a rate a little higher than the rate observed by Goessens et al [21] of only 1.5%.…”

Section: Discussionmentioning

confidence: 42%

Evaluation of the New VITEK 2 System for Determination of the Susceptibility of Clinical Isolates of <i>Streptococcus pneumoniae</i>

Diego

López²,

Coronilla³

et al. 2002

Chemotherapy

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“…Some single isolates generated multiple mEs when the reference MIC was close to a breakpoint value. As has been observed elsewhere (12), several (n ϭ 11) isolates were responsible for generating more than one mE within a method. These cases were observed with eight isolates that resulted in two errors each (Phoenix, five instances; Vitek 2, twice; and MicroScan, once), and three isolates were responsible for three errors each (Vitek 2, twice; Phoenix, once) (data not shown).…”

Section: Discussionsupporting

confidence: 69%

Comparison of BD Phoenix to Vitek 2, MicroScan MICroSTREP, and Etest for Antimicrobial Susceptibility Testing of Streptococcus pneumoniae

et al. 2009

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The performance of the BD Phoenix Automated Microbiology System (BD Diagnostic Systems) was compared to those of the Vitek 2 (bioMérieux), the MicroScan MICroSTREP plus (Siemens), and Etest (bioMérieux) for antibiotic susceptibility tests (AST) of 311 clinical isolates of Streptococcus pneumoniae. The overall essential agreement (EA) between each test system and the reference microdilution broth reference method for S. pneumoniae AST results was >95%. For Phoenix, the EAs of individual antimicrobial agents ranged from 90.4% (clindamycin) to 100% (vancomycin and gatifloxacin Streptococcus pneumoniae is the leading cause of communityacquired pneumonia in adults and serious respiratory infections in children in the United States. Globally, septicemia is a major cause of infant mortality in developing nations. Penicillin is the antimicrobial agent of choice, and macrolides are the second most common alternative. Within the last two decades, the emergence of strains of S. pneumoniae that are resistant to penicillin, macrolides, and other antimicrobial agents has become a serious health care problem (15). As of 2005, 18% of S. pneumoniae isolates in the United States were reported as penicillin resistant (9), and internationally they account for up to 60% of isolates (South Africa) (3).The rise in drug resistance of S. pneumoniae underscores the need for clinical microbiology laboratories to accurately determine its antimicrobial susceptibility profile in a timely manner. Rapid reporting of antimicrobial susceptibility test (AST) results has been shown to improve patient outcomes and to reduce hospital costs (2,10,19). To this end, automated AST systems offer the promise of shorter turnaround times to results. The literature includes reports evaluating the individual performance of each of the following AST systems for S. pneumoniae: Vitek 2, BD Phoenix, MicroScan MICroSTREP, and Etest (1,13,14,16,(20)(21)(22). However, to the best of our knowledge a cross-comparative study of all these systems has not been conducted to date. Therefore, the present study was designed to evaluate their performance and time to results (TTR).(Portions of this study were presented at the 106th General Meeting of the American Society for Microbiology, Orlando, FL, 2006, and at the 47th Interscience Conference on Antimicrobial Agents and Chemotherapy, Chicago, IL, 2007.) MATERIALS AND METHODS Test isolates.A total of 311 clinical isolates of S. pneumoniae, recovered from patients at the NewYork-Presbyterian Hospital, Columbia University Medical Center, were evaluated. All 311 strains were tested using the Phoenix, MicroScan, Etest, and PASCO reference method; 19 strains failed to grow with the Vitek 2, thus limiting the Vitek 2 evaluation to 292 clinical isolates. The specimen sources were predominately respiratory (70%), blood (12%), and eye (7%). Prior to testing, all isolates were subcultured onto BBL Columbia agar with 5% sheep blood and incubated at 35°C with 5% CO 2 for 18 to 24 h. Isolates were tested concurrently on all systems. Ma...

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“…The induced nitrocefin and penicillin MIC tests had equally high sensitivities and specificities. While the reference broth microdilution (BMD) penicillin MIC results correlated 100% with those of blaZ PCR, 259 (26.1%) isolates had penicillin MICs of 0.12 g/ml, near the susceptible breakpoint, which could prove problematic for automated antimicrobial susceptibility platforms that have a history of imperfect penicillin susceptibility detection (32)(33)(34)(35). However, no ␤-lactamase was detectable in tested isolates with penicillin MICs of Յ0.12 g/ml by reference broth microdilution, unlike S. aureus strains, which may harbor ␤-lactamase despite a susceptible penicillin MIC and thus require confirmation using the penicillin zone edge test (8).…”

Section: Discussionmentioning

confidence: 99%

Clinical and Microbiological Aspects of β-Lactam Resistance in Staphylococcus lugdunensis

et al. 2017

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Antimicrobial susceptibility results from broth microdilution MIC testing of 993 Staphylococcus lugdunensis isolates recovered from patients at a tertiary care medical center from 2008 to 2015 were reviewed. Ninety-two oxacillin-susceptible isolates were selected to assess the accuracy of penicillin MIC testing, the penicillin disk diffusion test, and three ␤-lactamase tests, including the cefoxitin-induced nitrocefin test, penicillin cloverleaf assay, and penicillin disk zone edge test. The results of all phenotypic tests were compared to the results of blaZ PCR. The medical records of 62 patients from whom S. lugdunensis was isolated, including 31 penicillinsusceptible and 31 penicillin-resistant strains, were retrospectively reviewed to evaluate the clinical significance of S. lugdunensis isolation, the antimicrobial agents prescribed, if any, and the clinical outcome. MIC testing revealed that 517/993 (52.1%) isolates were susceptible to penicillin and 946/993 (95.3%) were susceptible to oxacillin. The induced nitrocefin test was 100% sensitive and specific for the detection of ␤-lactamase compared to the blaZ PCR results, whereas the penicillin disk zone edge and cloverleaf tests showed sensitivities of 100% but specificities of only 9.1% and 89.1%, respectively. The penicillin MIC test had 100% categorical agreement with blaZ PCR, while penicillin disk diffusion yielded one major error. Only 3/31 patients with penicillin-susceptible isolates were treated with a penicillin family antimicrobial. The majority of cases were treated with other ␤-lactams, trimethoprimsulfamethoxazole, or vancomycin. These data indicate that nearly all isolates of S. lugdunensis are susceptible to narrow-spectrum antimicrobial agents. Clinical laboratories in areas with resistance levels similar to those described here can help promote the use of these agents versus vancomycin by effectively designing their antimicrobial susceptibility reports to convey this message.KEYWORDS Staphylococcus, antimicrobial resistance, beta-lactams, lugdunensis S taphylococcus spp. are normal skin flora inhabitants and, in some cases, opportunistic human pathogens (1). The coagulase-negative staphylococci (CoNS) are typically less virulent than Staphylococcus aureus in healthy human hosts. One exception is Staphylococcus lugdunensis, which may exhibit increased virulence compared to that of other CoNS (2). Infections associated with S. lugdunensis can include skin and soft tissue infections, native valve endocarditis, urinary tract infections, and prosthetic device infections (2).Isolates of CoNS, in particular Staphylococcus epidermidis, that harbor the mecA gene can have oxacillin MICs in the 0.5-to 2.0-g/ml range, which is much lower than the oxacillin MICs observed in mecA-positive isolates of S. lugdunensis and S. aureus (3-7). As such, the Clinical and Laboratory Standards Institute (CLSI) recommends that

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Evaluation of the Vitek 2 System for Susceptibility Testing of Streptococcus pneumoniae Isolates

Cited by 12 publications

References 13 publications

Evaluation of the New VITEK 2 System for Determination of the Susceptibility of Clinical Isolates of <i>Streptococcus pneumoniae</i>

Evaluation of the New VITEK 2 System for Determination of the Susceptibility of Clinical Isolates of <i>Streptococcus pneumoniae</i>

Comparison of BD Phoenix to Vitek 2, MicroScan MICroSTREP, and Etest for Antimicrobial Susceptibility Testing of Streptococcus pneumoniae

Clinical and Microbiological Aspects of β-Lactam Resistance in Staphylococcus lugdunensis

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