TABLE 3.

Results of identification of clinical staphylococcal isolates (n = 55) by 16S rDNA differentiation-based systems compared to biochemical assays

ResultaNo. (%) of isolates tested by:
16S rDNA-based identificationBiochemical identification
RIDOMGenBankID 32 StaphVITEK 2
Correctly identifiedb50 (90.9)36 (65.5)42 (76.4)36 (65.5)
Failure due to:
    Correct identification, but below acceptable valuesc1 (1.8)1 (1.8)6 (10.9)4 (7.3)
    Ambiguous results in the case of the highest match4 (7.3)18 (32.7)NAdNA
    Misidentification007 (12.7)15 (27.3)
Total failures5 (9.1)19 (34.5)13 (23.6)19 (34.5)
  • a Based on species level.

  • b For biochemical assays, classification is based on a %ID that is acceptable or better (%ID ≥ 80.0) and on a T index value that is acceptable or better (T ≥ 0); for 16S rDNA-based identification, classification is based on percent similarity (%S ≥ 98.5) to the 16S rDNA sequence of the type and reference strains.

  • c For biochemical assays, classification is based on a %ID that is below acceptable (%ID < 80.0) and on a T value that is below acceptable (T = 0); for 16S rDNA-based identification, classification is based on a %S of <98.5%.

  • d NA, not applicable.