Table 2
Performance characteristics of Gram stain compared with culture for identification of Staphylococcus aureus from BacT/ALERT blood culture bottles
| Microscopist* | Blood culture bottle type | No. Gram stains positive for S aureus/No. cultures positive for S aureus (% sensitivity) | No. Gram stains negative for S aureus/No. cultures negative for S aureus† (% specificity) | PPV (%) | NPV (%) |
|---|---|---|---|---|---|
| *Technologist experienced with the criteria; clinical microbiologist recently taught the criteria; †includes coagulase negative staphylococci and micrococcus species. | |||||
| NPV, negative predictive value; PPV, positive predictive value. | |||||
| Technologist | All | 59/66 (89) | 82/84 (98) | 59/61 (97) | 82/89 (92) |
| Aerobic | 26/31 (84) | 49/50 (98) | 26/27 (96) | 49/54 (91) | |
| Anaerobic | 33/35 (94) | 33/34 (97) | 33/34 (97) | 33/35 (94) | |
| Microbiologist | All | 58/66 (88) | 77/84 (92) | 58/65 (89) | 77/85 (91) |
| Aerobic | 24/31 (77) | 47/50 (94) | 24/27 (89) | 47/54 (87) | |
| Anaerobic | 34/35 (97) | 30/34 (88) | 34/38 (89) | 30/31 (97) | |
