Detection of vancomycin resistance in Enterococcus species

Willey, Barbara M.; Kreiswirth, Barry N; Simor, Andrew E.; Willaims, G; Scriver, S. R.; Phillips, Aled O.; Low, Donald E.

doi:10.1128/jcm.30.7.1621-1624.1992

Cited by 80 publications

(59 citation statements)

References 22 publications

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“…The improved current results probably reflect use of the 1992 NCCLS revised procedure. In our survey, the automated systems performed well and we did not confirm an earlier finding [27] that the Vitek GPS-TA card exhibited only 72% sensitivity for the detection of vancomycin resistance. Lack of sensitivity was thought to be due to insufficient growth in the wells.…”

Section: Discussioncontrasting

confidence: 99%

An interprovincial external quality assessment of the ability of Canadian laboratories to detect the vancomycin and penicillin resistance of Enterococcus faecium D366

Richardson

Noble

Fleming

et al. 1999

Clinical Microbiology and Infection

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Objective: To evaluate the ability of Canadian laboratories to identify enterococci and detect low-level resistance to penicillin, ampicillin and vancomycin in five provinces and two territories by two external quality assessment schemes.Methods: Enterococcus faecium, strain D366, with minimum inhibitory concentrations for vancomycin and penicillin of 32 and 16 mg/L respectively, was distributed during a routine proficiency survey. Laboratories were required to culture and identify the isolate and to test antimicrobial susceptibility. Participants were assessed against consensus reference values.Results: Three hundred and sixty-four hospital, commercial and public-health laboratories participated, using their established procedures for patient samples. The isolate was identified to the species level by 222 (61%) laboratories and to the genus level by a further 98 participants. Forty-four failed to meet the expected standard. Vancomycin resistance was detected by 94%. Those reporting a falsely susceptible result used disk diffusion testing. Penicillin resistance was noted by 250 of 258 laboratories reporting on this agent. An incorrect ampicillin-susceptible finding was reported by 62 of 147 laboratories using automated microdilution or agar dilution methods. Conclusions:Most laboratories identified the isolate to an appropriate level. Detection of low-level vancomycin and penicillin resistance was achieved by the majority. Ampicillin resistance was less readily detected.

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Section: Discussioncontrasting

confidence: 99%

An interprovincial external quality assessment of the ability of Canadian laboratories to detect the vancomycin and penicillin resistance of Enterococcus faecium D366

Richardson

Noble

Fleming

et al. 1999

Clinical Microbiology and Infection

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“…These are the vanA strains, which show high-level vancomycin resistance (MICs of Ͼ32 g/ml) and resistance to teicoplanin; vanB strains, which have variable resistance to vancomycin (MICs of 4 to Ն128 g/ml) and susceptibility to teicoplanin; and vanC motile strains, which show intrinsic resistance to low levels of vancomycin (MICs of 2 to 32 g/ml) and susceptibility to teicoplanin. From studies of vancomycin resistance, Willey et al showed the MicroScan Positive MIC Type 6 panels to have a sensitivity and specificity of 99 and 96%, respectively, when the visual inspection method of detection is used (27). In addition, other studies have shown these panels to be reliable except in cases in which low-level vancomycin resistance (MICs of 4 to 8 g/ ml) was present (22).…”

Section: Discussionmentioning

confidence: 99%

“…Automated systems, including the Vitek and MicroScan systems, have been developed to identify and to determine the antimicrobial susceptibility of enterococci (1,2,18,22,23,(25)(26)(27)(28). Previous studies have shown conventional MicroScan panels to be reliable in the identification of Enterococcus spe-cies, even though the data bank includes only E. faecalis, E. faecium, E. durans, and E. avium (24).…”

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confidence: 99%

“…Previous studies have shown conventional MicroScan panels to be reliable in the identification of Enterococcus spe-cies, even though the data bank includes only E. faecalis, E. faecium, E. durans, and E. avium (24). There are, however, conflicting reports on the reliability of the MicroScan system to detect ampicillin-and vancomycin-resistant strains of Enterococcus species (13,22,23,27).…”

mentioning

confidence: 99%

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Revised approach for identification and detection of ampicillin and vancomycin resistance in Enterococcus species by using MicroScan panels

et al. 1996

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The frequency of antimicrobial agent-resistant enterococci is increasing, making accurate identification and screening for susceptibility essential. We evaluated the ability of MicroScan Positive Breakpoint Combo Type 6 panels (Dade MicroScan Inc., West Sacramento, Calif.) to identify Enterococcus species and to detect ampicillin and vancomycin resistance. A total of 398 well-characterized Enterococcus isolates from two institutions were inoculated into MicroScan panels, into conventional biochemical assays, and into ampicillin and vancomycin agar dilution media. Resistance was verified by the broth macrodilution method. MicroScan panels accurately detected resistance to ampicillin in 132 of 132 enterococcal isolates, while three isolates for which the MICs were <16 g/ml were classified incorrectly by MicroScan panels as resistant. No beta-lactamaseproducing enterococci were detected. All 64 isolates showing resistance to vancomycin (MICs >32 g/ml) were correctly classified by MicroScan panels. Seven isolates for which the vancomycin MICs were 8 and 16 g/ml were incorrectly classified as susceptible by MicroScan panels, while eight isolates for which the MICs were 4 g/ml were incorrectly labeled as intermediate. Fourteen of these 15 isolates were subsequently identified as motile enterococci. Overall, there were three major errors in susceptibility testing for ampicillin and 15 minor errors for vancomycin. Conventional testing confirmed the identity of 181 Enterococcus faecalis isolates, 157 E. faecium isolates, and 60 isolates of other species; however, 56 of these 60 isolates were misidentified by the MicroScan panels. After recognition of this problem, a reviased approach which included tests for pigment, motility, and sucrose fermentation was devised. In combination with these additional assays, the conventional MicroScan panels accurately identified the 56 originally misidentified isolates. In summary, the ability of MicroScan panels to detect vancomycin and ampicillin resistance in enterococci was confirmed. Our study found that the inability of MicroScan panels to identify enterococci other than E. faecalis and E. faecium can be compensated for by the addition of standard assays.

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“…Only 35% of respondents used this agar, and 28% used Mueller-Hinton agar inappropriately. Although the original description of the vancomycin screening test reported the use of Mueller-Hinton agar, this was only a preliminary study, which was stated to require further evaluation [22]. The original method was optimised subsequently, and brain-heart infusion agar was found to be superior to Mueller-Hinton agar [23].…”

Section: Discussionmentioning

confidence: 99%

Antimicrobial susceptibility testing in European hospitals: report from the ARPAC study

Mackenzie

Bruce

Looveren

et al. 2006

Clinical Microbiology and Infection

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This observational study describes the antimicrobial susceptibility testing (AST) methods and interpretive criteria used in European hospitals during 2001, focusing specifically on detection of methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant enterococci (VRE). Of 263 hospitals that took part in the ARPAC study, 192 submitted data on AST. Of these, 89% (n = 170) routinely used a disk-diffusion AST method, 43% (n = 82) used a semi-automated method, and 70% (n = 135) routinely determined MICs. Hospitals in southern Europe were less likely to use disk-diffusion, but were more likely to use a semi-automated method (p <0.001). In total, 173 (90%) interpreted AST results using CLSI breakpoints; 30% of these detected MRSA using unmodified CLSI disk-diffusion methods, while 35% used the unmodified CLSI agar-screening method for MRSA; 41% and 30% adhered to unmodified CLSI methodology for disk-diffusion and agar-screening, respectively, to detect VRE. Some of the modifications made may have greatly reduced the ability of the tests to detect MRSA/VRE. For example, 20% of respondents used excessively high incubation temperatures and 13% used inadequate incubation times to detect MRSA by disk-diffusion, and 28% used Mueller-Hinton agar instead of brain-heart infusion agar in VRE screening plates. The majority of respondents stated that they followed CLSI guidelines, but a high proportion had modified the CLSI methods for detecting MRSA and VRE, which may compromise clinical management and antimicrobial resistance surveillance.

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Detection of vancomycin resistance in Enterococcus species

Cited by 80 publications

References 22 publications

An interprovincial external quality assessment of the ability of Canadian laboratories to detect the vancomycin and penicillin resistance of Enterococcus faecium D366

An interprovincial external quality assessment of the ability of Canadian laboratories to detect the vancomycin and penicillin resistance of Enterococcus faecium D366

Revised approach for identification and detection of ampicillin and vancomycin resistance in Enterococcus species by using MicroScan panels

Antimicrobial susceptibility testing in European hospitals: report from the ARPAC study

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