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

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.

Variability in urine culture reporting by Canadian microbiology laboratories.

OBJECTIVE: To determine the ability of microbiology laboratories to perform and to report urine colony counts. DESIGN: Clinical Microbiology Proficiency Testing program participants received stabilized simulated urine samples. Laboratories were asked to perform the appropriate test and report results. PARTICIPANTS: One hundred and nine clinical microbiology laboratories in British Columbia, Alberta and Nova Scotia. OUTCOME MEASURES: Consistency of reporting was compared with standards for reporting results as described in the SI Manual in Health Care, 2nd edition. RESULTS: The study demonstrated a wide variation in units used for the reporting of results. Ninety-five (87.2%) laboratories reported quantitative urine results in a variety of unit styles. Of those laboratories providing results with units, 80 (84.2%) used one of 10 variations of SI reporting styles. Fifteen (16.8%) laboratories reported metric units in three different styles. Eleven (10.0%) laboratories reported semiquantitative values without stating units. The remaining three (2.8%) did not respond to the survey. CONCLUSIONS: Many clinical microbiology laboratories have not adopted a consistent form of SI units for reporting quantitative urine culture results. This lack of consistency could potentially lead to interpretation confusion.