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Table 3 Predictive accuracy of sputum Gram stain for the etiologic diagnosis

From: Validation of sputum Gram stain for treatment of community-acquired pneumonia and healthcare-associated pneumonia: a prospective observational study

  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