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Table 3 Diagnostic performance of the Carba-R assay stratified by carbapenemase gene

From: Diagnostic performance of the Xpert Carba-R assay for active surveillance of rectal carbapenemase-producing organisms in intensive care unit patients

Carbapenemase gene (No. of carbapenemase genes detected by the Carba-R assay)CPO carriage by culture (%)No. of specimens with the following results% (95% confidence interval)
TotalTPFPTN*FNSensitivitySpecificityPPVNPV
KPC (n = 11)**†3.0406101393283.3 (51.6–97.9)99.8 (98.6–100.0)90.9 (58.2–98.6)99.5 (98.2–99.9)
NDM (n = 4)0.2406134020100.0 (2.5–100.0)99.3 (97.9–99.8)21.3 (8.1–45.5)100.0 (99.1–100.0)
VIM (n = 1)NA406014050NA99.8 (98.6–100.0)NA100.0 (99.1–100.0)
IMP-1 (n = 13)**†0.54062113930100.0 (15.8–100.0)97.3 (95.2–98.6)15.6 (9.3–24.8)100.0 (99.1–100.0)
OXA-48 (n = 1)**NA406014050NA99.8 (98.6–100.0)NA100.0 (99.1–100.0)
Total (n = 28)3.740615133780100.0 (78.2–100.0)96.7 (94.4–98.2)53.6 (40.4–66.4)100.0 (99.0–100.0)
  1. *Specimens not detected by the Carba-R assay were considered as true negative results
  2. **Two specimens were detected as KPC + IMP-1 and KPC + OXA-48
  3. †The other two specimens were excluded because the results of PCR or CRE culture were not available.
  4. Abbreviations: CPO carbapenemase-producing organism, TP true positive, FP false positive, TN true negative, FN false negative, PPV positive predictive value, NPV negative predictive value