TABLE 1.
Comparison of three methods for identification of Staphylococcus to the genus and species levels
| Organism | No. of isolates | No. of isolates (% correct) identified bya: |
No. of spectra in database | |||||
|---|---|---|---|---|---|---|---|---|
| Standard extraction |
On-plate extraction |
Direct colony |
||||||
| Genus level | Species level | Genus level | Species level | Genus level | Species level | |||
| Staphylococcus aureus | 64 | 64 (100) | 63 (98.4) | 64 (100) | 63 (98.4) | 64 (100) | 56 (87.5) | 12 |
| Staphylococcus epidermidis | 93 | 93 (100) | 87 (93.5) | 93 (100) | 89 (95.7) | 93 (100) | 64 (68.8) | 9 |
| Staphylococcus capitis | 20 | 20 (100) | 20 (100) | 20 (100) | 18 (90) | 20 (100) | 16 (80) | 6 |
| Staphylococcus caprae | 24 | 22 (91.6) | 1 (4.2) | 24 (100) | 18 (75) | 21 (87.5) | 6 (25) | 2 |
| Staphylococcus haemolyticus | 19 | 19 (100) | 18 (94.7) | 18 (94.7) | 17 (89.4) | 16 (88.9) | 7 (36.8) | 8 |
| Staphylococcus lugdunensis | 21 | 21 (100) | 21 (100) | 20 (95.2) | 19 (90.4) | 21 (100) | 17 (80.9) | 6 |
| Staphylococcus saprophyticus | 19 | 17 (89.4) | 1 (5.2) | 19 (100) | 15 (78.9) | 5 (26.3) | 0 (0) | 8 |
| Staphylococcus cohnii | 3 | 3 (100) | 0 (0) | 1 (33.3) | 0 (0) | 0 (0) | 0 (0) | 5 |
| Staphylococcus hominis | 7 | 7 (100) | 7 (100) | 7 (100) | 7 (100) | 7 (100) | 5 (71.4) | 6 |
| Staphylococcus pettenkoferi | 5 | 5 (100) | 2 (40) | 5 (100) | 5 (100) | 5 (100) | 1 (20) | 5 |
| Staphylococcus schleiferi | 6 | 6 (100) | 6 (100) | 6 (100) | 4 (66.7) | 2 (33.3) | 1 (16.6) | 6 |
| Staphylococcus warneri | 6 | 6 (100) | 6 (100) | 6 (100) | 2 (33.3) | 2 (33.3) | 0 (0) | 4 |
| Total | 287 | 283 (98.6) | 232 (80.8)* | 283 (98.6) | 257 (89.5)** | 256 (89.2) | 173 (60.2) | |
a
*, P < 0.05 against direct colony for species-level identification;
**
, P < 0.05 against both direct colony and standard extraction for species-level identification.