Detection of high-level aminoglycoside resistance in enterococci other than Enterococcus faecalis

Sahm, D F; Boonlayangoor, Sue; Schulz, John E.

doi:10.1128/jcm.29.11.2595-2598.1991

Cited by 36 publications

(21 citation statements)

References 13 publications

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“…Studies have shown that prolonged incubation does not have a beneficial effect (30), but there have been reports demonstrating significant improvement of test sensitivity for the detection of HLAR (25,36). In our current study, prolonging the incubation to 48 h increased the detection rate by 6.2% for occurrences of resistance (CP phase).…”

Section: Discussioncontrasting

confidence: 45%

“…Very major errors rarely occurred (1.0% for HLSR and 0.7% for HLGR). The most notable observation was the improved sensitivity of the PM-8 MicroScan panels for the detection of HLSR; earlier panels (25,30,36) detected isolates with HLSR at rates of only 41 to 90.2%. Reformulation of the panels with a modified basal broth appears to have enhanced the growth of enterococci resulting in improved test accuracy.…”

Section: Discussionmentioning

confidence: 99%

“…Reformulation of the panels with a modified basal broth appears to have enhanced the growth of enterococci resulting in improved test accuracy. In spite of the fact that highly accurate (98.6%) results were obtained with the QA method in the EP (6,25,27), problems with unacceptably high error rates (12.0 to 17.8%) were encountered in the CP and RP when using QA to detect HLSR. The factor causing different results for the detection of HLSR by QA between the EP and the CP and RP was considered to be the very major errors contributed exclusively by two unusual isolates, not a reagent problem (6).…”

Section: Discussionmentioning

confidence: 99%

“…Overall, 73.2% of strains tested for the VR genes were negative (range, 61.2 to 94.0%), while 23.5% produced a vanA or vanB PCR product, including four strains from WUSM harboring both genes. The remaining 3.4% of strains produced a band consistent with one of the vanC genotypes, usually associated with Enterococcus gallinarum, Enterococcus casseliflavus, and Enterococcus flavescens (12,18,25,31). The percentages of strains lacking the HLSR or HLGR gene were 54.4% (range, 36.0 to 74.0%) and 77.2% (range, 70.0 to 81.6%), respectively.…”

Section: Characterization Of Strainsmentioning

confidence: 98%

“…This synergistic combination therapy is clearly optimal for infections, such as endocarditis and meningitis, which require a bactericidal therapeutic effect (16). The widespread emergence of high-level resistance to aminoglycosides and glycopeptides among enterococci in Europe, North America, and other lo-cations (20,25,31) has brought the medical community one step closer to the postantimicrobial era.…”

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confidence: 99%

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Use of Molecular and Reference Susceptibility Testing Methods in a Multicenter Evaluation of MicroScan Dried Overnight Gram-Positive MIC Panels for Detection of Vancomycin and High-Level Aminoglycoside Resistances in Enterococci

Chen¹,

Marshall²,

Winokur

et al. 1998

J Clin Microbiol

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Modified MicroScan gram-positive MIC no. 8 panels (PM-8) were analyzed for their improved ability to detect vancomycin resistance (VR) and high-level aminoglycoside resistance (HLAR) in enterococci. A validation study design that utilized selected challenge strains, recent clinical isolates, and reproducibility experiments in a multicenter format was selected. Three independent medical centers compared the commercial panels to reference broth microdilution panels (RBM) and Synergy Quad Agar (QA). Resistance was verified by demonstration of VR and HLAR genes by PCR tests. The study was conducted in three phases. (i) In the challenge phase (CP), two well-characterized sets of enterococci were obtained from the Centers for Disease Control and Prevention; one set contained 50 isolates for VR testing and one contained 48 isolates for HLAR testing. In addition, a set of 47 well-characterized isolates representing diverse geographic areas, obtained from earlier national surveillance studies, was tested at the University of Iowa College of Medicine (UICM). (ii) In the efficacy phase (EP), each laboratory tested 50 recent, unique clinical isolates by all methods. (iii) In the reproducibility Phase (RP), each laboratory tested the same 10 strains by all methods in triplicate on three separate days. All isolates from the EP were sent to the UICM for molecular characterization of vanA, -B, -C 1 , -C 2-3 , and HLAR genes. In the CP, the ranking of test methods by error rates (in parentheses; very major and major errors combined, versus PCR results) were as follows: for high-level streptomycin resistance (HLSR), QA (12.0%) > PM-8 (5.2%) > RBM (1.6%); for high-level gentamicin resistance (HLGR), RBM (3.7%) > PM-8 (3.1%) > QA (2.6%); and for VR, RBM ‫؍‬ QA (3.0%) > PM-8 (1.2%). In the EP, agreement between all methods and the reference PCR result was 98.0% for HLSR, 99.3% for HLGR, and 98.6% for VR. In the RP, the percentages of results ؎ 1 log 2 dilution of the all-participant mode were as follows: for VR, 100% (PM-8), 98.9% (QA), and 90.0% (RBM); for HLSR, 99.6% (RBM), 98.5% (PM-8), and 82.2% (QA); and for HLGR, 99.6% (RBM), 99.3% (PM-8), and 98.1% (QA). The ability of the PM-8 to detect VR and HLAR in enterococci was comparable to those for reference susceptibility and molecular PCR methods and was considered acceptable for routine clinical laboratory use.

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Section: Discussioncontrasting

confidence: 45%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Characterization Of Strainsmentioning

confidence: 98%

mentioning

confidence: 99%

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Use of Molecular and Reference Susceptibility Testing Methods in a Multicenter Evaluation of MicroScan Dried Overnight Gram-Positive MIC Panels for Detection of Vancomycin and High-Level Aminoglycoside Resistances in Enterococci

Chen¹,

Marshall²,

Winokur

et al. 1998

J Clin Microbiol

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Special Phenotypic Methods for Detecting Antibacterial Resistance

Simner,

Humphries

2023

ClinMicroNow

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Special phenotypic tests may be performed as an adjunct or surrogate to standard antimicrobial susceptibility testing methods to help characterize an isolate's antimicrobial susceptibility to a drug or drug class or detect a particular resistance mechanism or phenotype. Special phenotypic susceptibility tests are categorized into supplemental tests, screening tests, surrogate agent tests, and equivalent agent tests. Phenotypic methods for the detection of resistance have been developed for use with both clinical specimens and cultured growth. Resistance to streptomycin is mediated by a different resistance mechanism, and consequently, streptomycin resistance must be determined separately from gentamicin resistance. Although erythromycin and clindamycin are in separate antimicrobial agent classes, i.e., macrolides and lincosamides, respectively, their mechanisms of action and mechanisms of resistance are similar. Antimicrobial resistance among Gram‐negative bacilli, and especially resistance to β‐lactam agents, is a serious public health concern worldwide.

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In Vitro Testing of Antibiotics

Ackerman,

Buono

1996

Pharmacotherapy

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To enhance knowledge in the area of in vitro testing of antibiotics and to understand the limitations of available methods for susceptibility testing, we conducted a MEDLINE literature search in the English language to accumulate relevant articles. Headings searched included microbial sensitivity tests; Kirby‐Bauer; laboratory tests; antiinfective agents; antibiotics, combined; microbiological techniques; blood bactericidal assay; and pharmacology, clinical. The management of patients with serious life‐threatening infections can be complicated by recent changes in organism nomenclature, newly marketed antibiotics, and new isolation and sensitivity testing methods. With the addition of formulary constraints, many problems and controversies arise regarding interpretation of antibiotic sensitivity results. Comprehensive care for infected patients requires assessment of current antibiotic therapy and options for alternative therapy. By applying pharmacodynamic and pharmacokinetic knowledge to known limits of in vitro testing results, the clinician is able to select the most efficient antibiotic or antibiotic combination.

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Detection of high-level aminoglycoside resistance in enterococci other than Enterococcus faecalis

Cited by 36 publications

References 13 publications

Use of Molecular and Reference Susceptibility Testing Methods in a Multicenter Evaluation of MicroScan Dried Overnight Gram-Positive MIC Panels for Detection of Vancomycin and High-Level Aminoglycoside Resistances in Enterococci

Use of Molecular and Reference Susceptibility Testing Methods in a Multicenter Evaluation of MicroScan Dried Overnight Gram-Positive MIC Panels for Detection of Vancomycin and High-Level Aminoglycoside Resistances in Enterococci

Special Phenotypic Methods for Detecting Antibacterial Resistance

In Vitro Testing of Antibiotics

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