Table 1.
Performance characteristics of CA, CNA, and the selective broth for detection of GBS from vaginal and rectal swabs
| Medium | Vaginal swabs (n = 130) |
Rectal swabs (n = 130) |
||||
|---|---|---|---|---|---|---|
| No. (%) positive for GBS | Sensitivity (%)a | Accuracy (%)b | No. (%) positive for GBS | Sensitivity (%)a | Accuracy (%)b | |
| CA | 41 (31.5) | 83.7 | 155/167 (92.8) | 38 (29.2) | 88.4 | 132/159 (83.0) |
| CNA | 34 (26.2) | 69.4 | 129/153 (84.3) | 31 (23.8) | 72.1 | 116/150 (77.3) |
| Selective broth | 39 (30.0) | 79.6 | 155/171 (90.6) | 12 (9.2) | 27.9 | 48/88 (54.5) |
| Total GBS isolated | 49 (37.7) | 43 (33.1) | ||||
a
Sensitivity was calculated in comparison to composite scores of all media.
b
Accuracy was calculated as the number of confirmed GBS colonies isolated/total number of GBS-like colonies that were confirmed as either positive or negative for GBS.