title: An interprovincial external quality assessment of the ability of Canadian laboratories to detect the vancomycin and penicillin resistance of Enterococcus faecium D366.
abstract: 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.
authors.affiliation: Laboratory Proficiency Testing Program, Toronto, Ontario.
authors.forename: H.
authors.initials: H
authors.lastname: Richardson
authors.forename: M. A.
authors.initials: MA
authors.lastname: Noble
authors.forename: C. A.
authors.initials: CA
authors.lastname: Fleming
authors.forename: S.
authors.initials: S
authors.lastname: Nikiforuk
authors.forename: A. M. R.
authors.initials: AM
authors.lastname: Mackenzie