scholarly journals Evaluation of the PASCO Strep Plus Broth Microdilution Antimicrobial Susceptibility Panels for Testing Streptococcus pneumoniae and Other Streptococcal Species

2000 ◽  
Vol 38 (5) ◽  
pp. 1713-1716 ◽  
Author(s):  
M. Jasmine Mohammed ◽  
Fred C. Tenover
Keyword(s):  
Streptococcus Pneumoniae ◽  
Antimicrobial Agent ◽  
Antimicrobial Susceptibility ◽  
Antimicrobial Agents ◽  
Clinical Laboratory ◽  
Reference Method ◽  
National Committee ◽  
Broth Microdilution ◽  
Streptococcal Species ◽  
Commercial Method

Antimicrobial resistance continues to increase worldwide among isolates of Streptococcus pneumoniae and other species of streptococci. Increasing rates of penicillin resistance, particularly in viridans group streptococci, and resistance to multiple classes of antimicrobial agents, including β-lactams, macrolides, and fluoroquinolones, in pneumococci have increased the importance of having accurate antimicrobial susceptibility testing results for guiding therapy. One commercial method of assessing resistance in streptococci is the PASCO Strep Plus panel. This broth microdilution-based method has recently been expanded to include a variety of newer antimicrobial agents. Therefore, we compared the results of the new PASCO Strep Plus panels for 26 antimicrobial agents against the results generated using the National Committee for Clinical Laboratory Standards (NCCLS) broth microdilution reference method for 75 pneumococci and 68 other streptococcal isolates. Only 4 (0.2%) very major errors (all with pneumococci and each with a different antimicrobial agent) were observed. There were 5 (0.3%) major errors observed with pneumococci (each with a different antimicrobial agent), but only 1 major error with nonpneumococcal streptococci. All of the very major and major errors resolved on retesting. Of the 65 (3.9%) and 17 (1.6%) minor errors observed with pneumococci and other streptococci, respectively, all were within 1 dilution of the broth microdilution reference MIC result. Thus, the PASCO Strep Plus panel has comparable accuracy to the NCCLS broth microdilution reference method.

scholarly journals Evaluation of the Dade MicroScan MICroSTREP Antimicrobial Susceptibility Testing Panel with Selected Streptococcus pneumoniae Challenge Strains and Recent Clinical Isolates

1998 ◽  
Vol 36 (3) ◽  
pp. 788-791 ◽  
Author(s):  
J. H. Jorgensen ◽  
M. L. McElmeel ◽  
S. A. Crawford
Keyword(s):  
Streptococcus Pneumoniae ◽  
Antimicrobial Agents ◽  
Susceptibility Testing ◽  
Clinical Laboratory ◽  
Reference Panel ◽  
Clinical Isolates ◽  
National Committee ◽  
Broth Microdilution ◽  
Drug Concentrations ◽  
Broth Microdilution Method

The MicroScan MICroSTREP panel is a recently marketed frozen broth microdilution panel for susceptibility testing of various streptococci, including Streptococcus pneumoniae. The panel contains 10 antimicrobial agents in cation-adjusted Mueller-Hinton broth supplemented with 3% lysed horse blood, similar in concept to the National Committee for Clinical Laboratory Standards (NCCLS) reference broth microdilution method for testing streptococci. A group of 210 isolates of S. pneumoniae were selected to include isolates with previously documented resistance to agents incorporated in the MICroSTREP panel, as well as recent invasive clinical isolates. All isolates were tested simultaneously with the MICroSTREP panel and an NCCLS reference panel whose drug concentrations were prepared to coincide with those of the MICroSTREP panel. Of the 210 isolates, 5 failed to grow in the MICroSTREP panel; 3 of those also did not grow in the reference panel. Essential agreement of MICs determined by the two methods (test MIC ± one dilution of the reference MIC) was 99.6% overall and ranged from 98.0% with chloramphenicol to 100% with penicillin, ceftriaxone, erythromycin, tetracycline, and vancomycin. There were no very major or major interpretive category errors resulting from the MICroSTREP panel tests. Minor interpretive category errors ranged from 12.2% with cefotaxime and 9.8% with ceftriaxone (due mainly to clustering of MICs for the selected strains near the breakpoints) to 0% with chloramphenicol and vancomycin. These results indicate that the MicroScan MICroSTREP frozen panels provide susceptibility results with pneumococci that are essentially equivalent to results derived by the NCCLS reference broth microdilution procedure.

scholarly journals Rapid Automated Antimicrobial Susceptibility Testing of Streptococcus pneumoniae by Use of the bioMerieux VITEK 2

2000 ◽  
Vol 38 (8) ◽  
pp. 2814-2818 ◽  
Author(s):  
James H. Jorgensen ◽  
Arthur L. Barry ◽  
M. M. Traczewski ◽  
Daniel F. Sahm ◽  
M. Leticia McElmeel ◽  
...  
Keyword(s):  
Streptococcus Pneumoniae ◽  
Antimicrobial Agents ◽  
Susceptibility Testing ◽  
Clinical Laboratory ◽  
Reference Method ◽  
Test Method ◽  
Clinical Isolates ◽  
National Committee ◽  
Vitek 2 ◽  
The Individual

The VITEK 2 is a new automated instrument for rapid organism identification and susceptibility testing. It has the capability of performing rapid susceptibility testing of Streptococcus pneumoniae with specially configured cards that contain enriched growth medium and antimicrobial agents relevant for this organism. The present study compared the results of testing of a group of 53 challenge strains of pneumococci with known resistance properties and a collection of clinical isolates examined in two study phases with a total of 402 and 416 isolates, respectively, with a prototype of the VITEK 2. Testing was conducted in three geographically separate laboratories; the challenge collection was tested by all three laboratories, and the unique clinical isolates were tested separately by the individual laboratories. The VITEK 2 results of tests with 10 antimicrobial agents were compared to the results generated by the National Committee for Clinical Laboratory Standards reference broth microdilution MIC test method. Excellent interlaboratory agreement was observed with the challenge strains. The overall agreement within a single twofold dilution of MICs defined by the VITEK 2 and reference method with the clinical isolates was 96.3%, although there were a number of off-scale MICs that could not be compared. The best agreement with the clinical isolates was achieved with ofloxacin and chloramphenicol (100%), and the lowest level of agreement among those drugs with sufficient on-scale MICs occurred with trimethoprim-sulfamethoxazole (89.7%). Overall there were 1.3% very major, 6.6% minor, and no major interpretive category errors encountered with the clinical isolates, although >80% of the minor interpretive errors involved only a single log2 dilution difference. The mean time for generation of susceptibility results with the clinical isolates was 8.1 h. The VITEK 2 provided rapid, reliable susceptibility category determinations with both the challenge and clinical isolates examined in this study.

Assessment of Laboratory Performance With Streptococcus pneumoniae Antimicrobial Susceptibility Testing in the United States

1999 ◽  
Vol 123 (4) ◽  
pp. 285-289 ◽  
Author(s):  
Gary V. Doern ◽  
Angela B. Brueggemann ◽  
Michael A. Pfaller ◽  
Ronald N. Jones
Keyword(s):  
United States ◽  
Streptococcus Pneumoniae ◽  
Antimicrobial Agents ◽  
Susceptibility Testing ◽  
Clinical Laboratory ◽  
The United States ◽  
National Committee ◽  
In Vitro Susceptibility ◽  
Susceptibility Tests

Abstract Objective.—To assess the performance of clinical microbiology laboratories in the United States when conducting in vitro susceptibility tests with Streptococcus pneumoniae. Methods.—The results of a nationwide College of American Pathologists Proficiency Survey test sample, in which susceptibility testing of an isolate of S pneumoniae was performed, were assessed with respect to precision and accuracy. Results.—Wide variability was noted among participating laboratories with both minimum inhibitory concentration procedures and disk diffusion susceptibility tests when both methods were applied to S pneumoniae. Despite this high degree of variation, categorical interpretive errors were uncommon. Numerous laboratories reported results for antimicrobial agents that are not recommended by the National Committee for Clinical Laboratory Standards for tests with S pneumoniae. Conclusions.—Current susceptibility testing practices with S pneumoniae in the United States indicate limited precision and a tendency for laboratories to test and report results obtained with antimicrobial agents of questionable therapeutic value against this organism. Continued efforts to standardize susceptibility testing of S pneumoniae in the United States are warranted. In addition, modifications of existing interpretive criteria may be necessary.

scholarly journals Effect of Metronidazole on the Growth of Vaginal Lactobacilliin vitro

2001 ◽  
Vol 9 (1) ◽  
pp. 41-45 ◽  
Author(s):  
Jose A. Simoes ◽  
Alla A. Aroutcheva ◽  
Susan Shott ◽  
Sebastian Faro
Keyword(s):  
Adverse Effect ◽  
Hydrogen Peroxide ◽  
Antimicrobial Agent ◽  
Clinical Laboratory ◽  
National Committee ◽  
Broth Microdilution ◽  
High Concentration ◽  
Microdilution Method ◽  
Broth Microdilution Method ◽  
The Ideal

Objective:To determine whether metronidazole has an adverse effect on the growth ofLactobacillus.Methods:Hydrogen peroxide- and bacteriocin-producing strains ofLactobacilluswere used as test strains. Concentrations of metronidazole used ranged from 128 to 7000 μg/ml. Susceptibility to metronidazole was conducted by the broth microdilution method recommended by the National Committee for Clinical Laboratory Standards.Results:Growth ofLactobacilluswas partially inhibited at concentrations between 1000 and 4000 μg/ml (p= 0.014). Concentrations ≥ 5000 μg/ml completely inhibited growth ofLactobacillus. Concentrations between 128 and 256 μg/ml stimulated growth ofLactobacillus(p= 0.025 and 0.005, respectively). Concentrations of metronidazole between 64 and 128 μg/ml or ≥ 512 μg/ml did not have an inhibitory or a stimulatory effect on the growth ofLactobacilluscompared to the control.Conclusions:High concentration of metronidazole, i.e. between 1000 and 4000 μg/ml, partially inhibited the growth ofLactobacillus. Concentrations ≥ 5000 μg/ml completely suppressed the growth ofLactobacillus. Concentrations between ≥ 128 and ≤ 256 μg/ml stimulated the growth ofLactobacillus. Further investigation to determine the ideal concentration of metronidazole is needed in order to use the antimicrobial agent effectively in the treatment of bacterial vaginosis.

scholarly journals Methods for Improved Detection of Oxacillin Resistance in Coagulase-Negative Staphylococci: Results of a Multicenter Study

1999 ◽  
Vol 37 (12) ◽  
pp. 4051-4058 ◽  
Author(s):  
Fred C. Tenover ◽  
Ronald N. Jones ◽  
Jana M. Swenson ◽  
Barbara Zimmer ◽  
Sigrid McAllister ◽  
...  
Keyword(s):  
Clinical Laboratory ◽  
Reference Method ◽  
Disk Diffusion ◽  
National Committee ◽  
Broth Microdilution ◽  
Pcr Assay ◽  
Coagulase Negative Staphylococci ◽  
Oxacillin Resistance ◽  
Disk Diffusion Testing ◽  
Single Disk

A multilaboratory study was undertaken to determine the accuracy of the current National Committee for Clinical Laboratory Standards (NCCLS) oxacillin breakpoints for broth microdilution and disk diffusion testing of coagulase-negative staphylococci (CoNS) by using a PCR assay for mecA as the reference method. Fifty well-characterized strains of CoNS were tested for oxacillin susceptibility by the NCCLS broth microdilution and disk diffusion procedures in 11 laboratories. In addition, organisms were inoculated onto a pair of commercially prepared oxacillin agar screen plates containing 6 μg of oxacillin per ml and 4% NaCl. The results of this study and of several other published reports suggest that, in order to reliably detect the presence of resistance mediated bymecA, the oxacillin MIC breakpoint for defining resistance in CoNS should be lowered from ≥4 to ≥0.5 μg/ml and the breakpoint for susceptibility should be lowered from ≤2 to ≤0.25 μg/ml. In addition, a single disk diffusion breakpoint of ≤17 mm for resistance and ≥18 mm for susceptibility is suggested. Due to the poor sensitivity of the oxacillin agar screen plate for predicting resistance in this study, this test can no longer be recommended for use with CoNS. The proposed interpretive criteria for testing CoNS have been adopted by the NCCLS.

scholarly journals Quality Control Guidelines for Disk Diffusion and Broth Microdilution Antimicrobial Susceptibility Tests with Seven Drugs for Veterinary Applications

2000 ◽  
Vol 38 (1) ◽  
pp. 453-455
Author(s):  
Brant A. Odland ◽  
Meredith E. Erwin ◽  
Ronald N. Jones
Keyword(s):  
Quality Control ◽  
Antimicrobial Susceptibility ◽  
Susceptibility Testing ◽  
Clinical Laboratory ◽  
Disk Diffusion ◽  
National Committee ◽  
Broth Microdilution ◽  
E Coli ◽  
Antimicrobial Susceptibility Tests ◽  
Susceptibility Tests

ABSTRACT This multicenter study proposes antimicrobial susceptibility (MIC and disk diffusion methods) quality control (QC) parameters for seven compounds utilized in veterinary health. Alexomycin, apramycin, tiamulin, tilmicosin, and tylosin were tested by broth microdilution against various National Committee for Clinical Laboratory Standards (NCCLS)-recommended QC organisms ( Staphylococcus aureus ATCC 29213, Enterococcus faecalis ATCC 29212, Streptococcus pneumoniae ATCC 49619, Escherichia coli ATCC 25922, and Pseudomonas aeruginosa ATCC 27853). In addition, disk diffusion zone diameter QC limits were determined for apramycin, enrofloxacin, and premafloxacin by using E. coli ATCC 25922, P. aeruginosa ATCC 27853, and S. aureus ATCC 25923. The results from five or six participating laboratories produced ≥99.0% of MICs and ≥95.0% of the zone diameters within suggested guidelines. The NCCLS Subcommittee for Veterinary Antimicrobial Susceptibility Testing has recently approved these ranges for publication in the next M31 document.

scholarly journals Antimicrobial Susceptibilities of Diverse Bacillus anthracis Isolates

2002 ◽  
Vol 46 (12) ◽  
pp. 3843-3845 ◽  
Author(s):  
Pamala R. Coker ◽  
Kimothy L. Smith ◽  
Martin E. Hugh-Jones
Keyword(s):  
Bacillus Anthracis ◽  
Antimicrobial Susceptibility ◽  
Antimicrobial Agents ◽  
Clinical Laboratory ◽  
National Committee ◽  
Field Isolates ◽  
Antimicrobial Susceptibilities

ABSTRACT A test of 25 genetically diverse isolates of Bacillus anthracis was conducted to determine their susceptibility to seven clinically relevant antimicrobial agents. Etest strips (AB BIODISK, Solna, Sweden) were used to measure the MICs for the isolates. Using the National Committee for Clinical Laboratory Standards MIC breakpoints for staphylococci, three isolates were found to be resistant to penicillin and five were found to be resistant to cefuroxime. The penicillin-resistant isolates were negative for β-lactamase production. Continued surveillance of B. anthracis field isolates is recommended to monitor antimicrobial susceptibility.

scholarly journals Correlation between E-Test, Disk Diffusion, and Microdilution Methods for Antifungal Susceptibility Testing of Fluconazole and Voriconazole

2003 ◽  
Vol 47 (5) ◽  
pp. 1647-1651 ◽  
Author(s):  
Madonna J. Matar ◽  
Luis Ostrosky-Zeichner ◽  
Victor L. Paetznick ◽  
Jose R. Rodriguez ◽  
Enuo Chen ◽  
...  
Keyword(s):  
Susceptibility Testing ◽  
Clinical Laboratory ◽  
Antifungal Susceptibility ◽  
Reference Method ◽  
Antifungal Susceptibility Testing ◽  
Disk Diffusion ◽  
National Committee ◽  
Broth Microdilution ◽  
Microdilution Method ◽  
Test Disk

ABSTRACT The activities of fluconazole and voriconazole against isolates of Candida spp. (n = 400) were tested by the E-test, disk diffusion, and the National Committee for Clinical Laboratory Standards (NCCLS) M27-A2 broth microdilution-based reference methods. More than 96% of isolates found to be susceptible to fluconazole by the reference method were identified as susceptible by the agar-based methods. Lesser degrees of correlation with the reference method were seen for isolates identified as resistant by the agar-based methods. Interpretive categories are not available for voriconazole, but results qualitatively similar to those for fluconazole were seen. The agar-based E-test and disk diffusion methods are reliable alternatives to the NCCLS M27-A2 reference microdilution method for isolates that test susceptible to fluconazole.

scholarly journals Fluconazole Susceptibility Testing of Cryptococcus neoformans: Comparison of Two Broth Microdilution Methods and Clinical Correlates among Isolates from Ugandan AIDS Patients

1998 ◽  
Vol 36 (10) ◽  
pp. 2874-2876 ◽  
Author(s):  
C. J. Jessup ◽  
M. A. Pfaller ◽  
S. A. Messer ◽  
J. Zhang ◽  
M. Tumberland ◽  
...  
Keyword(s):  
Cryptococcus Neoformans ◽  
Clinical Laboratory ◽  
Reference Method ◽  
National Committee ◽  
Yeast Nitrogen Base ◽  
Broth Microdilution ◽  
Aids Patients ◽  
In Vitro Susceptibility ◽  
Nitrogen Base ◽  
Broth Microdilution Method

We compared the yeast nitrogen base (YNB) broth microdilution method with the National Committee for Clinical Laboratory Standards (NCCLS) M27-A microdilution reference method for measuring the in vitro susceptibility of Cryptococcus neoformans isolates to fluconazole. A total of 149 isolates of C. neoformans var.neoformans from Ugandan AIDS patients was tested by both methods. An overall agreement of 88% between the two microdilution methods was observed. All isolates grew well in both RPMI 1640 and YNB media, and MICs could be read after 48 h of incubation by both methods. The range of fluconazole MICs obtained with the YNB method was broader than that obtained with the NCCLS method. The extended range of MICs provided by the YNB method may be of clinical value, as it appears that the clinical outcome may be better among patients infected with strains inhibited by lower concentrations of fluconazole as determined by the YNB method. The YNB method appears to be a viable option for testing C. neoformans against fluconazole.

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