Table 2.
Evaluation of positive BSI-PCR results in 196 critically ill patients with presumed sepsis
| Pathogen or target | Primary analysisa | Discrepancy analysisb | |||||||
|---|---|---|---|---|---|---|---|---|---|
| True positive | False positive | True positive range | False positive range | ||||||
| (n) | n (PPV) | (95% CI) | n (FPP) | (95% CI) | n | (PPV) | n | (FPP) | |
| A. Species-specific PCRs | |||||||||
| E. faecalis | (16) | 7 (44%) | (20–70) | 9 (3%) | (1–5) | 11–12 | (69–75%) | 4–5 | (1–2%) |
| E. faecium | (11) | 9 (82%) | (48–98) | 2 (1%) | (0–2) | 10 | (91%) | 1 | (0%) |
| S. aureus | (34) | 15 (44%) | (27–62) | 19 (6%) | (4–9) | 15–18 | (44–53%) | 16–19 | (5–6%) |
| S. pneumoniae | (17) | 12 (71%) | (44–90) | 5 (2%) | (1–4) | 13 | (76%) | 4 | (1%) |
| A. baumannii | (1) | 0 | – | 1 (0%) | (0–2) | 0–1 | (0–100%) | 0–1 | (0–0%) |
| E. coli | (58) | 33 (57%) | (43–70) | 25 (8%) | (5–11) | 45–46 | (78–79%) | 12–13 | (4–4%) |
| Klebsiella | (11) | 7 (64%) | (31–90) | 4 (1%) | (0–3) | 9–10 | (82–91%) | 1–2 | (0–1%) |
| P. aeruginosa | (32) | 5 (16%) | (5–33) | 27 (8%) | (6–12) | 5–7 | (16–22%) | 25–27 | (8–8%) |
| C. albicans | (0) | – | – | – | – | ||||
| C. glabrata | (0) | – | – | – | – | ||||
| C. krusei | (0) | – | – | – | – | ||||
| Total A. | (180) | 88 (49%) | (41–56%) | 92 (3%) | (2–3%) | 108–117 | (60–65%) | 63–72 | (2–2%) |
| B. Generic PCRs | |||||||||
| Enterococcus | (25) | 12 (48%) | (28–69) | 13 (4%) | (2–7) | 16–17 | (64–68%) | 8–9 | (2–3%) |
| Staphylococcus | (24) | 11 (46%) | (26–67) | 13 (4%) | (2–7) | 12 | (50%) | 12 | (4%) |
| Gram-positive | (30) | 25 (83%) | (65–94) | 5 (2%) | (1–4) | 30 | (100%) | 0 | – |
| Gram-negative | (33) | 30 (91%) | (76–98) | 3 (1%) | (0–3) | 33 | (100%) | 0 | – |
| 3Candida | (2) | 1 (50%) | (1–99) | 1 (0%) | (0–2) | 2 | (100%) | 0 | – |
| Pan-Aspergillus | (1) | 0 | – | 1 (0%) | (0–2) | 0 | – | 1 | (0%) |
| Total B. | (115) | 79 (69%) | (59–77) | 36 (2%) | (1–3) | 93–94 | (81–82%) | 21–22 | (1–1%) |
| Total | (295) | 167 (57%) | (51–62) | 128 (2%) | (2–3) | 201–211 | (68–72%) | 84–94 | (2–2%) |
n, number of positive BSI-PCR results (multiple positive results possible per patient); CI, confidence interval; PPV, positive predictive value (= true positive/(true positive + false positive)); FPP, false positive proportion (= false positive/total number performed (n = 325 per PCR))
aFor the primary analysis positive BSI-PCR results were compared with the reference pathogens based on a prospective registration of most likely causative pathogen(s) within the MARS study
bFor the discrepancy analysis, false positive BSI-PCR results based on the primary analysis were adjudicated by an expert panel. Since 10 results were classified as “undetermined” by the panelists, a range was calculated for the PPV and FPP by classifying the undetermined results firstly as false positive and subsequently as true positive