Comparison of workflow and accuracy of identification and antimicrobial susceptibility testing of clinical isolates of Enterobacteriaceae, Pseudomonas aeruginosa and enterococci by Vitek 2 and routine methods.
Three hundred and fifty-three consecutive urine cultures growing Enterobacteriaceae, Pseudomonas aeruginosa or enterococci were subjected to parallel identification (ID) and antimicrobial susceptibility testing (AST) by Vitek 2 and routine methods, including simple screening tests or API 20 E for ID and standardized disc diffusion for AST. Accuracy of results, technician hands-on time required by both methods and time to results were compared. Vitek 2 correctly identified 322 (94.7%) of the 340 gram-negative isolates and 17 (81%) of the 21 Enterococcus faecalis strains. AST by Vitek 2 and disc diffusion gave category agreement for 4,058 (95.5%) of 4,248 organism-antimicrobial agent combinations. With MIC determination by E-test as reference, AST by Vitek 2 and disc diffusion produced 15 and 3 very major errors, respectively. Six (40%) of the fifteen very major errors by Vitek 2 were associated with trimethoprim-sulfamethoxazole. With an average of 22 specimens processed per day, use of Vitek 2 saved 80 min per day of technician hands-on time as compared to routine methods. Regarding the cost of hands-on worktime and consumables, use of Vitek 2 for identification of Escherichia coli-screened Enterobacteriaceae saved 0.70 p per sample in comparison to API 20 E. More than 80% of Enterobacteriaceae introduced to Vitek 2 in the morning could be reported by 16:00.
Rantakokko-Jalava
Kaisu
K
Clinical Microbiology Laboratory, Turku University Central Hospital, Finland. Kaisu.Rantakokko-Jalava@tyks.fi
Elo-Lehtonen
Eija
E
Meurman
Olli
O
D000900:Anti-Bacterial Agents / Q000494:pharmacology; D024881:Drug Resistance, Bacterial; D004755:Enterobacteriaceae / Q000187:drug effects / Q000302:isolation & purification*; D006801:Humans; D008826:Microbial Sensitivity Tests / Q000295:instrumentation* / Q000379:methods; D011550:Pseudomonas aeruginosa / Q000187:drug effects / Q000302:isolation & purification*; D015203:Reproducibility of Results; D014556:Urine / Q000382:microbiology*
D000900:Anti-Bacterial Agents