Table 3 Predictive accuracy of sputum Gram stain for the etiologic diagnosis
| Â | Sensitivity | Specificity | PPV | NPV | LR (+) | LR (-) |
|---|---|---|---|---|---|---|
GPDC (Streptococcus pneumoniae) | 62.5 (70/112) | 91.5 (335/366) | 69.3 (70/101) | 88.9 (335/377) | 7.38 | 0.41 |
GNCB (Haemophilus influenzae) | 60.9 (67/110) | 95.1 (350/368) | 78.8 (67/85) | 89.1 (350/393) | 12.5 | 0.41 |
GNDC (Moraxella catarrhalis) | 68.2 (30/44) | 96.1 (417/434) | 63.8 (30/47) | 96.8 (417/431) | 17.4 | 0.33 |
GNR-large (Klebsiella pneumoniae) | 39.5 (15/38) | 98.2 (432/436) | 65.2 (15/23) | 95.0 (432/455) | 21.7 | 0.62 |
GNR-small (Pseudomonas aeruginosa) | 22.2 (6/27) | 99.8 (450/451) | 85.7 (6/7) | 95.5 (450/471) | 100.2 | 0.78 |
GPC-cluster (Staphylococcus aureus) | 9.1 (1/11) | 100 (467/467) | 100 (1/1) | 97.1 (467/477) | - | 0.91 |