Table 2.
Sensitivities, specificities, PPVs and NPVs of the four different algorithms for the detection of 3GCREB tested on 478 clinical specimens
| Detection target (3GCREB or ESBL-E) Samples considered and used detection algorithm | No. of samples | Sensitivity, % (95% CI) | Specificity, % (95% CI) | PPV, % (95% CI) | NPV, % (95% CI) | Prevalence, % (95% CI) | ||
|---|---|---|---|---|---|---|---|---|
| TPa | FPb | FNc | ||||||
| Detection of 3GCREB | ||||||||
| All growth consideredd | ||||||||
| Stool without pre-enrichment (A) | 60 | 46 | 27 | 69.0 (58.0–78.2) | 88.2 (84.5–91.2) | 56.6 (46.6–66.1) | 92.7 (89.5–95.1) | 18.2 (14.9–22.0) |
| Stool with pre-enrichment (B) | 72 | 52 | 15 | 82.8 (72.8–89.7) | 86.7 (82.8–89.8) | 58.1 (48.9–66.8) | 95.8 (93.0–97.5) | 18.2 (14.9–22.0) |
| Rectal swab without pre-enrichment (C) | 58 | 29 | 29 | 66.7 (55.7–76.2) | 92.6 (89.4–94.9) | 66.7 (55.7–76.2) | 92.6 (89.4–94.9) | 18.2 (14.9–22.0) |
| Rectal swab with pre-enrichment (D) | 70 | 50 | 17 | 80.5 (70.3–87.9) | 87.2 (83.4–90.3) | 58.3 (49.0–67.2) | 95.3 (92.4–97.1) | 18.2 (14.9–22.0) |
| Stool total (A + B) | 75 | 64 | 12 | 86.2 (76.8–92.4) | 83.6 (79.5–87.1) | 54.0 (45.3. - 62.4) | 96.5 (93.7–98.1) | 18.2 (14.9–22.0) |
| Rectal swab total (C + D) | 74 | 52 | 13 | 85.1 (75.4–91.5) | 86.7 (82.8–89.8) | 58.7 (49.6–67.3) | 96.3 (93.6–97.9) | 18.2 (14.9–22.0) |
| Selected growth considerede | ||||||||
| Stool without pre-enrichment (A) | 60 | 25 | 27 | 69.0 (58.0–78.2) | 93.6 (90.6–95.7) | 70.6 (59.6–79.7) | 93.1 (90.0–95.3) | 18.2 (14.9–22.0) |
| Stool with pre-enrichment (B) | 72 | 20 | 15 | 82.8 (72.8–89.7) | 94.9 (92.1–96.8) | 78.3 (68.2–85.9) | 96.1 (93.5–97.7) | 18.2 (14.9–22.0) |
| Rectal swab without pre-enrichment (C) | 58 | 15 | 29 | 66.7 (55.7–76.2) | 96.2 (93.6–97.8) | 79.5 (68.1–87.7) | 92.8 (89.8–95.1) | 18.2 (14.9–22.0) |
| Rectal swab with pre-enrichment (D) | 70 | 13 | 17 | 80.5 (70.3–87.9) | 96.7 (94.2–98.1) | 84.3 (74.3–91.1) | 95.7 (93.1–97.4) | 18.2 (14.9–22.0) |
| Stool total (A + B) | 75 | 29 | 12 | 86.2 (76.8–92.4) | 92.6 (89.4–94.9) | 72.1 (62.3–80.2) | 96.8 (94.3–98.3) | 18.2 (14.9–22.0) |
| Rectal swab total (C + D) | 74 | 17 | 13 | 85.1 (75.4–91.5) | 95.7 (93.0–97.4) | 81.3 (71.5–88.4) | 96.6 (94.2–98.1) | 18.2 (14.9–22.0) |
| Detection of ESBL-E | ||||||||
| All growth consideredd | ||||||||
| Stool without pre-enrichment (A) | 42 | 64 | 6 | 87.5 (74.1–94.8) | 85.1 (81.3–88.3) | 39.6 (30.4–49.6) | 98.4 (96.3–99.3) | 10.0 (7.6–13.2) |
| Stool with pre-enrichment (B) | 44 | 80 | 4 | 91.7 (79.1–97.3) | 81.4 (77.3–84.9) | 35.5 (27.2–44.6) | 98.9 (96.9–99.6) | 10.0 (7.6–13.2) |
| Rectal swab without pre-enrichment (C) | 40 | 47 | 8 | 83.3 (69.2–92.0) | 89.1 (85.6–91.8) | 46.0 (35.4–57.0) | 98.0 (95.8–99.0) | 10.0 (7.6–13.2) |
| Rectal swab with pre-enrichment (D) | 41 | 79 | 7 | 85.4 (71.6–93.5) | 81.6 (77.6–85.1) | 34.2 (25.9–43.5) | 98.0 (95.8–99.1) | 10.0 (7.6–13.2) |
| Stool total (A + B) | 46 | 93 | 2 | 95.8 (84.6–99.3) | 78.4 (74.1–82.1) | 33.1 (25.5–41.6) | 99.4 (97.7–99.9) | 10.0 (7.6–13.2) |
| Rectal swab total (C + D) | 43 | 83 | 5 | 89.6 (76.6–96.1) | 80.7 (76.6–84.3) | 34.1 (26.1–43.2) | 98.6 (96.5–99.5) | 10.0 (7.6–13.2) |
| Selected growth considerede | ||||||||
| Stool without pre-enrichment (A) | 42 | 43 | 6 | 87.5 (74.1–94.8) | 90.0 (86.7–92.6) | 49.4 (38.5–60.4) | 98.5 (96.5–99.4) | 10.0 (7.6–13.2) |
| Stool with pre-enrichment (B) | 44 | 48 | 4 | 91.7 (79.1–97.3) | 88.8 (85.4–91.6) | 47.8 (37.4–58.4) | 99.0 (97.2–99.7) | 10.0 (7.6–13.2) |
| Rectal swab without pre-enrichment (C) | 40 | 33 | 8 | 83.3 (69.2–92.0) | 92.3 (89.3–94.6) | 54.8 (42.8–66.3) | 98.0 (96.0–99.1) | 10.0 (7.6–13.2) |
| Rectal swab with pre-enrichment (D) | 41 | 42 | 7 | 85.4 (71.6–93.5) | 90.2 (86.9–92.8) | 49.4 (38.3–60.5) | 98.2 (96.2–99.2) | 10.0 (7.6–13.2) |
| Stool total (A + B) | 46 | 58 | 2 | 95.8 (84.6–99.3) | 86.5 (82.8–89.5) | 44.2 (34.6–54.3) | 99.5 (97.9–99.9) | 10.0 (7.6–13.2) |
| Rectal swab total (C + D) | 43 | 48 | 5 | 89.6 (76.6–96.1) | 88.8 (85.4–91.6) | 47.3 (36.8–57.9) | 98.7 (96.8–99.5) | 10.0 (7.6–13.2) |
A combined gold standard consisting of all four approaches was applied for the calculation
aTP, true positive. A result was considered TP when at least one 3GCREB isolate was recovered from the sample
bFP, false positive. A result was considered FP when the isolate(s) recovered from the sample was not confirmed to be a 3GCREB
cFN, false negative
dWhen no selection criteria were applied (for calculation, all oxidase positive/negative and all colored/uncolored colonies growing on ESBL agar were counted)
eWhen selection criteria were applied (only oxidase negative and colored colonies growing on ESBL agar were counted)