Performance of VITEK-2 Compact and overnight MicroScan panels for direct identification and susceptibility testing of Gram-negative bacilli from positive FAN BacT/ALERT blood culture bottles.
We describe the reliability of the VITEK-2 Compact and overnight MicroScan panels for direct identification and susceptibility testing from the BacT/ALERT blood culture system when using FAN (FA and FN) bottles. A simple procedure, in two centrifugation steps, was designed to remove the charcoal particles present in FA and FN bottles. A total of 113 positive blood cultures showing Gram-negative rods were investigated. Enterobacteriaceae were isolated in 104 cases, and Pseudomonas aeruginosa in nine. The MicroScan system correctly identified 106 (93.8%) of the 113 isolates. The seven identificaction errors included P. aeruginosa (three), Enterobacter cloacae (one), Escherichia coli (one), Klebsiella oxytoca (one), and Klebsiella pneumoniae (one). The VITEK-2 system correctly identified 109 (96.5%) of the 113 samples obtained directly from the blood culture bottles. The four unidentified isolates were Enterobacter cloacae (two), Escherichia coli (one), and P. aeruginosa (one). MicroScan yielded 4/779 (0.5%) very major errors and 28/2825 (0.9%) minor errors. VITEK-2 yielded 2/550 (0.36%) very major errors, 1/1718 (0.05%) major error, and 32/2373 (1.3%) minor errors. Both systems provided excellent identification (correlation of >90%) and susceptibility (correlation of >98%) results. The average times required to obtain identification and susceptibility results using the direct test applied to the VITEK-2 Compact system were 4.57 +/- 1.37 h and 6.52 +/- 1.64 h, respectively. The VITEK-2 compact system provided results on the same day that the blood culture was found to be positive.
Department of Microbiology, Hospital Universitari Germans Trias i Pujol, Universitat Autònoma de Barcelona, Badalona, Spain.
M D
MD
Quesada
M
M
Giménez
S
S
Molinos
G
G
Fernández
M D
MD
Sánchez
R
R
Rivelo
A
A
Ramírez
G
G
Banqué
V
V
Ausina
D000900:Anti-Bacterial Agents / Q000494:pharmacology; D016470:Bacteremia / Q000175:diagnosis* / Q000382:microbiology; D001769:Blood / Q000382:microbiology*; D003951:Diagnostic Errors; D004755:Enterobacteriaceae / Q000187:drug effects / Q000302:isolation & purification*; D004756:Enterobacteriaceae Infections / Q000175:diagnosis* / Q000382:microbiology; D006801:Humans; D008826:Microbial Sensitivity Tests; D011552:Pseudomonas Infections / Q000175:diagnosis* / Q000382:microbiology; D011550:Pseudomonas aeruginosa / Q000187:drug effects / Q000302:isolation & purification*; D012680:Sensitivity and Specificity; D013997:Time Factors
D000900:Anti-Bacterial Agents