Table 2.
Performance characteristics of CNA and CA with respect to the order of plating
| Specimen | CNA |
CA |
Trans-Vaga |
Total no. (%) positive for GBS | |||
|---|---|---|---|---|---|---|---|
| No. (%) positive for GBS | Sensitivity (%) | No. (%) positive for GBS | Sensitivity (%) | No. (%) positive for GBS | Sensitivity (%) | ||
| Plated first on CAN | |||||||
| Vaginal (n = 65) | 20 (30.8) | 80 | 21 (32.3) | 84 | 23 (35.4) | 92 | 25 (38.5) |
| Rectal (n = 65) | 18 (27.7) | 94.7 | 16 (24.6) | 84.2 | 8 (12.3) | 42.1 | 19 (29.2) |
| Total (n = 130) | 38 (29.2) | 86.4 | 37 (28.5) | 84.1 | 31 (23.8) | 70.4 | 44 (33.8) |
| Plated first on CA | |||||||
| Vaginal (n = 65) | 14 (21.5) | 58.3 | 20 (30.8) | 83.3 | 16 (24.6) | 66.7 | 24 (36.9) |
| Rectal (n = 65) | 13 (20) | 54.2 | 22 (33.8) | 91.7 | 4 (6.2) | 16.7 | 24 (36.9) |
| Total (n = 130) | 27 (20.8) | 56.2 | 42 (32.3) | 87.5 | 20 (15.4) | 41.7 | 48 (36.9) |
a
After direct plating, the swab was placed in Trans-Vag broth.